{"title":"Focal Extenders","description":"\u003cp\u003eFocal Extenders from every brand we carry. Part of \u003ca href=\"\/collections\/flatteners-and-reducers\"\u003eFlatteners, Reducers \u0026amp; Correctors\u003c\/a\u003e.\u003c\/p\u003e","products":[{"product_id":"explores-scientific-2x-2-focal-extender","title":"Explore Scientific 2x 2-Inch Telecentric Focal Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 2x Focal Extender is a 2-inch telecentric amplifier that doubles the effective focal length of the telescope it is fitted to. The body is 118mm long and 66mm wide, and Explore Scientific's current spec sheet gives its weight as 20 oz (0.57 kg). Explore Scientific describes it as compatible with both 1.25-inch and 2.0-inch eyepiece barrel sizes, for visual observing and for imaging.\u003c\/p\u003e\n\u003cp\u003eThe optics use multiple precision elements in a telecentric arrangement, with EMD coating on the air-to-glass surfaces and edge-blackened elements to hold contrast. Because the design is telecentric rather than a simple negative Barlow, the amplification factor stays at 2x regardless of how far the eyepiece or camera sits behind it.\u003c\/p\u003e\n\u003cp\u003ePractically, that means one focal extender doubles every eyepiece you own. A 20mm becomes a 10mm, a 14mm becomes a 7mm, and the apparent field and eye relief of each eyepiece carry through unchanged.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers filling gaps in a set:\u003c\/strong\u003e two eyepieces plus this extender cover four magnifications, which is a compact way to build a range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary and lunar observers:\u003c\/strong\u003e reaching high power by doubling a longer eyepiece keeps the eye relief of the longer eyepiece rather than the cramped eye position of a very short one.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e Explore Scientific specifically notes the telecentric design's benefit here, because eye relief is inherited from the eyepiece rather than compressed by the amplifier.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary imagers:\u003c\/strong\u003e doubling focal length raises image scale on the Moon and planets, and telecentricity keeps that factor predictable regardless of camera spacing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e2x amplification, telecentric:\u003c\/strong\u003e the factor holds constant no matter what spacing the eyepiece or camera sits at, which a conventional Barlow does not do.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.0-inch barrel\u003c\/strong\u003e for 2-inch focusers and diagonals, with compatibility for both 1.25-inch and 2-inch eyepieces as published by Explore Scientific.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMultiple precision elements\u003c\/strong\u003e in the optical group; Explore Scientific does not publish the element count.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEMD coating on the air-to-glass surfaces,\u003c\/strong\u003e which is where a multi-element amplifier gains or loses transmission and contrast.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEdge-blackened elements\u003c\/strong\u003e to suppress the internal scatter that otherwise shows as a lowered contrast floor on planetary detail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePublished dimensions:\u003c\/strong\u003e 118mm long, 66mm wide, 20 oz (0.57 kg).\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA conventional Barlow lens is a negative group placed ahead of focus. It works, but its amplification factor depends on the distance between the lens and the eyepiece field stop — move the eyepiece further back and a nominal 2x becomes 2.3x or 2.5x. Anything that changes that distance, such as a diagonal inserted between the two or a different eyepiece with a deeper field stop, changes the effective magnification and makes the resulting figure an estimate.\u003c\/p\u003e\n\u003cp\u003eA telecentric design adds a positive group after the negative one, so the light leaving the assembly travels as a bundle of rays parallel to the optical axis. Two things follow. The amplification stays at exactly 2x whatever the spacing behind it, so the arithmetic on magnification and image scale remains exact. And the light entering the eyepiece arrives as though it came from a much slower telescope, which is easier on eyepiece designs that show edge aberrations at steep light cones.\u003c\/p\u003e\n\u003cp\u003eThe eyepiece keeps its own characteristics through the extender. Apparent field is unchanged, eye relief is unchanged, and the true field simply halves along with the doubling of magnification. That is why doubling a 14mm to reach 7mm is more comfortable than using a 7mm directly — the eye position belongs to the 14mm.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power lunar and planetary observing without buying very short focal length eyepieces.\u003c\/li\u003e\n\u003cli\u003eSplitting double stars, where the extra magnification is what opens a tight pair.\u003c\/li\u003e\n\u003cli\u003ePlanetary imaging, where doubling focal length raises image scale on a small sensor.\u003c\/li\u003e\n\u003cli\u003eUse with fast telescopes, where the telecentric output is gentler on eyepiece edge performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits 2-inch focusers and diagonals.\u003c\/strong\u003e Explore Scientific publishes compatibility with both 1.25-inch and 2.0-inch eyepiece barrel sizes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e double whatever the eyepiece gives on its own. In a 714mm telescope, a 20mm eyepiece goes from 36x to 71x; a 9mm goes from 79x to 159x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEffective focal ratio:\u003c\/strong\u003e doubles as well. An f\/5 telescope behaves as f\/10 behind it, an f\/7 as f\/14 — which is the figure that matters for planetary imaging exposure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging:\u003c\/strong\u003e because the factor is spacing-independent, a camera can sit at whatever backfocus the train needs and the image scale stays predictable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocus travel:\u003c\/strong\u003e an extender shifts the focus point outward, so the focuser racks in further than it would without it. Most telescopes have the travel; a very short-travel focuser is worth a check, and we can look at that with you.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e the 2-inch barrel accepts standard 2-inch threaded filters, so a lunar or minus-violet filter can sit ahead of the optics rather than at the eyepiece.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDoubling magnification also doubles the effect of atmospheric turbulence.\u003c\/strong\u003e On an unsteady night the extended view softens, which is seeing rather than the optics. On a steady night it is where the aperture shows what it can do.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt needs a 2-inch focuser or diagonal.\u003c\/strong\u003e A telescope with only a 1.25-inch focuser is outside its range, and Explore Scientific makes a 1.25-inch focal extender for exactly that case — tell us your focuser and we will point you at the right one.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific publishes two weight figures across revisions.\u003c\/strong\u003e The current spec sheet lists 20 oz (0.57 kg); an earlier sheet listed 752 grams (26.5 oz). Both are recorded as published rather than averaged into one number.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe element count is not published,\u003c\/strong\u003e so that row reads as not published below rather than carrying a guess. We can ask our Explore Scientific rep if it matters to you.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAn extender adds length to the imaging train.\u003c\/strong\u003e At 118mm it needs room behind the focuser, which is worth a look on a compact refractor with a short drawtube. Send us the telescope and we will check the geometry with you.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — it slides into a 2-inch focuser or diagonal, and the eyepiece slides into it. Refocusing after fitting it is the only step, and there is nothing to align or adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the difference between this and a Barlow?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA Barlow's amplification varies with the spacing behind it, so a nominal 2x can drift to 2.5x depending on the eyepiece and whether a diagonal is in the path. This is telecentric, so 2x stays 2x at any spacing, and the exit light is parallel to the axis rather than converging.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it work with my 1.25-inch eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExplore Scientific publishes compatibility with both 1.25-inch and 2.0-inch eyepiece barrels. The unit itself seats in a 2-inch focuser or diagonal.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it change my eye relief?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. The eyepiece keeps its own eye relief and apparent field — only the magnification changes. That is why doubling a longer eyepiece is more comfortable than using a very short one.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it for photography?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, particularly for the Moon and planets, where doubling focal length raises image scale. The telecentric design keeps the factor exact regardless of where the camera sensor sits.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a telecentric 2x focal extender with a 2-inch barrel, EMD-coated and edge-blackened elements, 118mm long at 20 oz, that doubles every eyepiece in your case while leaving apparent field and eye relief untouched. If you would like to know exactly which magnifications it will open up with the eyepieces you already own, send us the list and your telescope's focal length and we will work them out.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44012806930543,"sku":"FE02-020","price":249.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/2xx_compact__37521.png?v=1766548235"},{"product_id":"explores-scientific-2x-1-25-field-extender","title":"Explore Scientific 2x 1.25-Inch Telecentric Focal Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 2x Focal Extender is a 1.25-inch Barlow-type accessory that doubles the magnification of whatever eyepiece is placed in it. It is 96mm long, 45mm wide and weighs 260 grams (9.1 oz), and it is built on a telecentric optical layout using multiple precision lens elements rather than the single negative lens a simple Barlow uses.\u003c\/p\u003e\n\u003cp\u003eThe practical consequence of that layout is consistency. In a classic Barlow, the amplification factor depends on how far the eyepiece's field stop sits from the negative lens, so a 2x Barlow becomes a 2.3x or a 2.7x when spacing changes — when a diagonal goes in between, for instance, or when a different eyepiece design puts its field stop somewhere else. A telecentric design produces an exit beam whose rays run parallel to the optical axis, which holds the magnification factor at 2x regardless of spacing and keeps the eyepiece's own eye relief and image quality intact.\u003c\/p\u003e\n\u003cp\u003eThe result is that one 2x extender effectively doubles the number of magnifications your eyepiece set delivers: a 20mm becomes a 10mm-equivalent power, a 15mm becomes 7.5mm, a 30mm becomes 15mm — each while keeping the eye relief characteristics of the longer eyepiece.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e this is the most useful case of all. Short-focal-length eyepieces are where eye relief runs out; using a longer eyepiece behind a telecentric extender gives high magnification while retaining the comfortable eye position of the longer eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLunar and planetary observers\u003c\/strong\u003e who need to reach the magnifications where surface detail lives on the nights when seeing allows it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary imagers:\u003c\/strong\u003e doubling the focal length increases the image scale at the sensor, which is how a small planetary disc is made to cover enough pixels to resolve detail.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTelecentric optical layout:\u003c\/strong\u003e the defining feature. Multiple precision lens elements produce a parallel exit beam, holding the 2x factor constant regardless of the distance to the eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConsistent 2x amplification:\u003c\/strong\u003e the number on the barrel is the number you get, in a diagonal or straight into the focuser.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePreserves eye relief:\u003c\/strong\u003e the eyepiece behaves as it normally would, so its comfortable eye position carries through to the higher magnification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25-inch barrel:\u003c\/strong\u003e fits any standard 1.25-inch focuser or diagonal, and accepts any 1.25-inch eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePublished dimensions:\u003c\/strong\u003e 96mm long, 45mm wide, 260 grams (9.1 oz).\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA Barlow lens is a diverging optical group placed ahead of focus. It makes the converging light cone from the telescope shallower, which pushes the focal point further back and increases the effective focal length — and therefore the magnification. In its simplest form a single negative lens does the job, and it does it well enough for most purposes.\u003c\/p\u003e\n\u003cp\u003eThe weakness of the simple form is that the amount of amplification depends on where the eyepiece's field stop lands relative to that negative lens. Move the eyepiece further back and the factor rises. Insert a star diagonal between the Barlow and the eyepiece and the factor rises again. That is why a nominal 2x Barlow can end up delivering anywhere from 2x to nearly 3x depending on how it is used, which makes it hard to know what magnification you are actually observing at.\u003c\/p\u003e\n\u003cp\u003eA telecentric design solves this with a multi-element group that does more than diverge the beam. It re-forms the light so the chief rays exit parallel to the optical axis, which means the eyepiece behind it sees essentially the same geometry no matter where it sits. The amplification factor stays at 2x, the eyepiece's designed eye relief is preserved rather than compressed or stretched, and the correction the eyepiece was designed to deliver is not disturbed by the extra optics ahead of it.\u003c\/p\u003e\n\u003cp\u003eThere is one physical consequence worth understanding. Doubling the effective focal length also doubles the effective focal ratio: an f\/6 telescope behaves like an f\/12 one behind this extender. That halves the exit pupil for any given eyepiece and reduces image brightness accordingly, which is why focal extenders belong to lunar, planetary and double-star observing rather than to faint deep-sky work.\u003c\/p\u003e\n\u003cp\u003eExplore Scientific does not publish the exact element count for this extender, describing it as multiple precision lens elements, and does not publish a filter thread specification. Those rows are marked unpublished below rather than estimated.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power lunar observing, where doubling a mid-range eyepiece reaches crater-floor detail along the terminator.\u003c\/li\u003e\n\u003cli\u003ePlanetary observing on steady nights — Jovian belt structure, the Cassini division, Martian surface markings.\u003c\/li\u003e\n\u003cli\u003ePlanetary and lunar imaging, where doubling the focal length gives the image scale a small planetary disc needs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal,\u003c\/strong\u003e and accepts any 1.25-inch eyepiece. In a 2-inch focuser it seats in a 2-inch to 1.25-inch adapter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e telescope focal length × 2 ÷ eyepiece focal length. In a 952mm telescope, a 20mm eyepiece goes from 48x to 95x; a 12mm from 79x to 159x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEffective focal ratio:\u003c\/strong\u003e doubles. An f\/6 telescope works at f\/12 behind the extender, and an f\/10 at f\/20.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExit pupil:\u003c\/strong\u003e halves for a given eyepiece, which is why the extender pairs best with mid and long focal length eyepieces rather than the shortest one in the case.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDoubling magnification halves image brightness for a given eyepiece.\u003c\/strong\u003e That is fine on the Moon and the planets, and it is why deep-sky observing generally stays at native focal length. The extender is a Solar System and double-star tool.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeeing sets the ceiling, not the optics.\u003c\/strong\u003e On a turbulent night, higher magnification enlarges the turbulence along with the target. The extender earns its keep on steady nights, which is exactly what it was made for.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePairing it with your shortest eyepiece often overshoots.\u003c\/strong\u003e A 2x extender behind a 5mm in a metre-focal-length telescope produces magnification most apertures cannot support. Mid-range eyepieces are the productive partners, and the results are visibly better.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific does not publish the element count or a filter thread figure\u003c\/strong\u003e for this extender, so those rows read as unpublished rather than estimated. If either matters, ask and we will check with our Explore Scientific rep.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — the extender goes into the focuser or diagonal and the eyepiece goes into the extender. There is nothing to adjust, and because the design is telecentric, the spacing does not need to be set precisely to get the stated 2x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the difference between this and a regular Barlow?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA simple Barlow's amplification factor changes with spacing, so a nominal 2x can become 2.5x or more once a diagonal or a different eyepiece is involved. A telecentric design produces a parallel exit beam, so it stays at 2x regardless, and it preserves the eyepiece's own eye relief instead of altering it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eDouble whatever the eyepiece gives on its own. Telescope focal length × 2, divided by eyepiece focal length. A 1000mm telescope with a 20mm eyepiece goes from 50x to 100x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it good for eyeglass wearers?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt is one of the best answers there is. Instead of buying a very short eyepiece with minimal eye relief, you use a longer, more comfortable eyepiece behind the extender and get the same magnification with the eye relief the longer eyepiece was designed around.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 1.25-inch 2x focal extender with a telecentric multi-element design that holds its amplification factor and its eye relief regardless of spacing, at 96mm long and 260 grams. It doubles the number of magnifications your eyepiece set delivers and is particularly useful if you observe with glasses on. If you would like a second opinion on which of your eyepieces it pairs with best, send us the list and your telescope's focal length and we will work it through with you.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44012807716975,"sku":"FE02-125","price":165.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/2x_compact__89719.png?v=1766548241"},{"product_id":"explore-scientific-3x-1-25-field-extender","title":"Explore Scientific 3x 1.25-Inch Telecentric Focal Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 3x Focal Extender is a 1.25-inch telecentric amplifier that triples the magnification of whatever eyepiece is placed in it. Explore Scientific publishes a length of 93mm, a width of 45mm and a weight of 249 grams (8.7 oz), and describes the optical design as telecentric, using multiple precision lens elements to deliver light rays parallel to the optical axis.\u003c\/p\u003e\n\u003cp\u003eThat last point is what separates a telecentric focal extender from a conventional Barlow. In a Barlow, the amplification factor depends on how far the eyepiece field stop sits from the negative lens — add an extension or a diagonal into the train and the stated 2x quietly becomes 2.4x. A telecentric design sends the light out parallel, so the magnification stays at 3x regardless of the spacing behind it. What you calculate is what you get.\u003c\/p\u003e\n\u003cp\u003eThe other consequence is eye relief. A 3x extender lets a comfortable long-focal-length eyepiece do the work of a very short one: a 15mm eyepiece behind this unit performs like a 5mm while keeping the 15mm's eye relief. For eyeglass wearers and for anyone who finds short-focal-length eyepieces cramped, that is the main reason to own one.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLunar and planetary observers\u003c\/strong\u003e who want to reach high magnification without buying the very shortest eyepieces in a series.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e the extender preserves the eye relief of the eyepiece in front of it, which is exactly what short eyepieces sacrifice.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOwners of fast telescopes:\u003c\/strong\u003e at f\/4 or f\/5 a 3x extender turns the effective focal ratio into f\/12 or f\/15 at the eyepiece, which eases the demands on eyepiece design at the field edge.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble-star observers\u003c\/strong\u003e who need magnification on demand without swapping through a whole case.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary imagers\u003c\/strong\u003e using a 1.25-inch camera nose, where telecentric output keeps the amplification factor predictable in the image scale calculation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e3x magnification factor:\u003c\/strong\u003e a full three times, applied to whatever eyepiece is inserted.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTelecentric optical design:\u003c\/strong\u003e multiple precision lens elements arranged to emit rays parallel to the optical axis, so the amplification does not drift with spacing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEye relief preserved:\u003c\/strong\u003e the eyepiece keeps its own eye relief, so a long eyepiece at high power stays comfortable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25-inch barrel:\u003c\/strong\u003e fits any standard 1.25-inch focuser or diagonal.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePublished dimensions:\u003c\/strong\u003e 93mm long, 45mm wide, 249 grams (8.7 oz).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConsistent scale for imaging:\u003c\/strong\u003e because the factor is fixed, image scale calculations for planetary capture stay reliable.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA conventional Barlow lens is a negative element placed ahead of focus. It makes the converging light cone from the telescope shallower, which pushes focus further back and increases the effective focal length. The catch is that the amount of increase depends on the distance between the negative lens and the eyepiece field stop. Move the eyepiece back — by adding an extension tube, a filter wheel, or a diagonal in the wrong place — and the amplification climbs above the printed figure.\u003c\/p\u003e\n\u003cp\u003eA telecentric design solves this by adding positive elements behind the negative group so that the exit rays leave parallel to the optical axis rather than diverging. Parallel rays mean the effective amplification stops depending on how far away the next component sits. A 3x telecentric extender is 3x with a diagonal in the train, 3x with an extension tube, and 3x with a camera on the back.\u003c\/p\u003e\n\u003cp\u003eThe trade with any amplifier is light. Tripling magnification spreads the same photons over nine times the area, so the image is dimmer and the exit pupil shrinks to a third of what the eyepiece alone would give. That is why an extender belongs on bright targets: the Moon, the planets, double stars, and the brighter compact deep-sky objects.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power lunar and planetary observing without a dedicated short-focal-length eyepiece.\u003c\/li\u003e\n\u003cli\u003eSplitting close double stars.\u003c\/li\u003e\n\u003cli\u003ePlanetary and lunar imaging with a 1.25-inch camera, where a predictable amplification factor matters to image scale.\u003c\/li\u003e\n\u003cli\u003eExtending a modest eyepiece set into a larger range of magnifications.\u003c\/li\u003e\n\u003cli\u003eObserving with eyeglasses at high power, where a long eyepiece behind the extender keeps the eye relief.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal.\u003c\/strong\u003e In a 2-inch focuser it takes a 2-inch to 1.25-inch adapter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eResulting magnification:\u003c\/strong\u003e telescope focal length ÷ eyepiece focal length × 3. A 20mm eyepiece in a 952mm telescope gives 143x; a 15mm in a 1200mm gives 240x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEffective focal length:\u003c\/strong\u003e the telescope behaves as though its focal length were tripled — a 714mm f\/7 refractor becomes 2142mm at f\/21 at the eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePairing:\u003c\/strong\u003e mid and long focal length eyepieces are the natural partners. A 25mm, 20mm or 15mm behind this unit produces the equivalent of an 8.3mm, 6.7mm or 5mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhere it stops helping:\u003c\/strong\u003e putting a 3mm or 4mm eyepiece behind a 3x extender exceeds the useful magnification of nearly any aperture. The long end of your case is where the gains are.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging:\u003c\/strong\u003e a 1.25-inch camera nose fits directly. Because the design is telecentric, the amplification stays at 3x whatever the backfocus, which keeps the plate scale calculation honest.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e Explore Scientific does not publish the filter thread specification for this extender, so we are not quoting one. Filters can also be threaded onto the eyepiece instead, which is the usual arrangement.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e3x is a large step, and the atmosphere has a vote.\u003c\/strong\u003e On a steady night in a well-cooled telescope it opens up the top of the magnification range; on a turbulent night a 2x extender or the eyepiece alone will show more detail. Many observers keep both factors on hand for that reason, and we stock the 2x as well.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe image gets dimmer as it gets bigger.\u003c\/strong\u003e Three times the magnification means roughly one ninth the surface brightness, which is why bright targets are where an extender earns its place.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific publishes two slightly different sets of physical figures for this item\u003c\/strong\u003e — 93mm and 249 grams on the current product page, 96mm and 260 grams on the spec sheet supplied with earlier stock. The optical specification is the same; the difference is in production revisions. If the exact dimension matters for a case, ask us and we will confirm it with our rep.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eElement count and coatings are not published\u003c\/strong\u003e beyond the description of multiple precision lens elements, so those rows read \"Not published by vendor\" below rather than carrying an estimate.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — the extender goes into the focuser or diagonal, the eyepiece goes into the extender, and that is the whole procedure. Refocusing after fitting it is normal, since the extender moves the focal point outward.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the difference between this and a Barlow?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA Barlow's amplification changes with the spacing behind it. A telecentric extender sends light out parallel to the optical axis, so 3x stays 3x whatever else is in the train — diagonal, extension tube or camera.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it reduce eye relief?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo, and that is one of the main reasons to use one. The eyepiece keeps its own eye relief, so a 20mm eyepiece at 3x gives the magnification of a 6.7mm with the comfort of a 20mm.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhich eyepieces should I pair it with?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe mid and long focal lengths in your case. A 25mm, 20mm or 15mm become the equivalent of 8.3mm, 6.7mm and 5mm. Very short eyepieces behind a 3x go past what most apertures can use.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it for photography?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, for lunar and planetary imaging with a 1.25-inch camera. The fixed telecentric factor is a practical advantage, because the image scale calculation stays correct no matter what spacing the camera ends up at.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it work with my telescope?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAny telescope with a 1.25-inch focuser or diagonal takes it, and a 2-inch focuser takes it through an adapter. Whether 3x is the right factor depends on your focal length and aperture — send us those and we will tell you which factor suits.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 1.25-inch telecentric 3x focal extender at 93mm and 249 grams that triples magnification with a fixed, spacing-independent factor and leaves the eyepiece's eye relief intact — a straightforward way to turn the comfortable half of your eyepiece case into a high-power set. If you would like a recommendation on whether 2x or 3x suits your telescope's focal length better, send us the figures and we will work it out with you.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44012809027695,"sku":"FE03-125","price":193.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/3x_compact__06275.png?v=1766548248"},{"product_id":"explore-scientific-2-3x-focal-extender","title":"Explore Scientific 3x 2-Inch Telecentric Focal Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific FE03-020 is a 3x focal extender in the 2-inch format, 125mm long and 66mm wide. Explore Scientific list its weight two ways — 22 oz on the specification table and 1.7 lbs. on the product page — and both figures are reproduced verbatim below rather than reconciled by us.\u003c\/p\u003e\n\u003cp\u003eA focal extender does what a Barlow does, by a different optical route. It multiplies the effective focal length of the telescope by three, which triples the magnification of whatever eyepiece sits behind it and multiplies the working focal ratio by the same factor. A 1000mm f\/8 telescope becomes an effective 3000mm at f\/24. A 24mm eyepiece behaves as an 8mm, taking that telescope from 42x to 125x. A 30mm becomes an effective 10mm at 100x.\u003c\/p\u003e\n\u003cp\u003eWhat separates this from a conventional Barlow is the telecentric design. Explore Scientific describe it as using multiple precision lens elements to deliver light rays that remain parallel to the optical axis, which means the magnification factor stays at 3x regardless of how far the eyepiece or camera sits behind it. A simple negative-lens Barlow does not behave that way: its amplification climbs as the spacing grows, so a diagonal or a filter drawer between Barlow and eyepiece changes the factor. Here it does not.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary and lunar observers:\u003c\/strong\u003e 3x turns a comfortable medium-power eyepiece into a high-power one without giving up its eye relief or apparent field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOwners of ultra-wide 2-inch eyepieces:\u003c\/strong\u003e tripling a 24mm or 30mm ultra-wide gives high magnification with the eye position and field of the original eyepiece, which is not something a short focal-length eyepiece can offer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary imagers:\u003c\/strong\u003e a fixed 3x that does not drift with spacing makes the image scale predictable when a camera sits at an arbitrary distance behind it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnyone consolidating an eyepiece case:\u003c\/strong\u003e one extender effectively doubles the number of magnifications a set of eyepieces provides.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e3x magnification factor:\u003c\/strong\u003e triples the effective focal length of the telescope and the magnification of every eyepiece used with it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTelecentric optical design:\u003c\/strong\u003e multiple precision elements arranged so that emerging rays run parallel to the optical axis, holding the factor at 3x independent of spacing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEMD (Enhanced Multi-Layer Deposition) coatings:\u003c\/strong\u003e applied to the lens surfaces to raise transmission and suppress internal reflection through what is a multi-element optical train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEdge-blackened elements:\u003c\/strong\u003e the ground edges of the lenses are blackened so that stray light striking them is absorbed rather than scattered into the image.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.0-inch barrel:\u003c\/strong\u003e fits 2-inch focusers and diagonals, and takes 2-inch eyepieces and camera adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e125mm long, 66mm wide:\u003c\/strong\u003e the published physical dimensions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePublished weight:\u003c\/strong\u003e 22 oz on the specification table, 1.7 lbs. on the product page — both from Explore Scientific.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA conventional Barlow lens is a negative element placed in the converging beam ahead of focus. It slows the convergence, moving the focal plane further back and increasing the effective focal length. The amplification depends on where the negative element sits relative to the new focal plane, which is why a Barlow's marked factor is only accurate at one particular spacing. Insert a star diagonal, a filter drawer or an extension tube behind it and the true factor rises above the number printed on the barrel.\u003c\/p\u003e\n\u003cp\u003eA telecentric design solves that by adding positive elements after the negative group, arranged so that the chief rays leave the assembly parallel to the optical axis rather than diverging. Once the beam is telecentric, moving the eyepiece or the camera sensor backwards changes the back focus but not the amplification. Three times is three times, whether the eyepiece is seated directly in the extender or sitting behind a diagonal.\u003c\/p\u003e\n\u003cp\u003eThat property matters for more than convenience. In imaging, a predictable image scale is what allows a calculated pixel scale to be trusted, and it makes the combination of extender, filter wheel and camera a matter of achieving focus rather than recalculating magnification. The cost of a telecentric group is element count and, therefore, air-to-glass surfaces — which is where the EMD coatings and blackened element edges do their work, and why a telecentric extender is a physically larger object than a simple Barlow of the same nominal power.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power lunar and planetary observing using medium focal-length eyepieces.\u003c\/li\u003e\n\u003cli\u003eSplitting close double stars in apertures that can support the magnification.\u003c\/li\u003e\n\u003cli\u003ePlanetary and lunar imaging, where the fixed amplification keeps image scale predictable.\u003c\/li\u003e\n\u003cli\u003eExtending the useful range of an existing 2-inch eyepiece set without buying short focal lengths.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits 2-inch focusers and diagonals.\u003c\/strong\u003e Eyepieces and camera adapters in the 2-inch format go into the top of it. A 1.25-inch eyepiece can be used through a 2-inch to 1.25-inch adapter, which we stock.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEffective focal length:\u003c\/strong\u003e multiply your telescope's focal length by three. A 750mm Newtonian becomes 2250mm; a 1900mm Maksutov becomes 5700mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEffective focal ratio:\u003c\/strong\u003e also multiplied by three. An f\/5 telescope works at f\/15 behind this extender, which is worth knowing for exposure planning in imaging.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEye relief:\u003c\/strong\u003e unchanged. The eyepiece behaves as a shorter focal length while keeping its own eye relief and apparent field, which is the main reason observers use an extender rather than buying a very short eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocus travel:\u003c\/strong\u003e adding 125mm of optical train ahead of the eyepiece shifts the focus position outward. Most 2-inch focusers have the travel for it; a telescope already near the end of its inward travel is the one case where it is worth checking, and we can look at that with you.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e3x is a large step.\u003c\/strong\u003e On a 200mm telescope, a 24mm eyepiece behind this extender produces a magnification most nights of average seeing will not support. It is an eyepiece-case tool for the steady nights rather than an every-session accessory — and on those nights it is exactly the right thing to reach for.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a substantial piece of hardware.\u003c\/strong\u003e Explore Scientific publish 22 oz on the specification table and 1.7 lbs. on the product page. Either way, with a 2-inch eyepiece on top of it there is real mass hanging off the focuser, so the drawtube tension is worth setting firmly. A focuser upgrade is the answer where the existing one cannot hold it, and we can advise on that.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is 2-inch only.\u003c\/strong\u003e Telescopes with 1.25-inch focusers cannot take it directly; the 1.25-inch focal extenders in the same range are the ones that suit those.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific does not publish the element count or an optical-length figure for this extender,\u003c\/strong\u003e so those rows are absent rather than estimated. For an imaging train where backfocus has to be calculated, send us the camera and spacers you are working with and we will sort the arithmetic out with you.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification has a ceiling set by aperture.\u003c\/strong\u003e Roughly twice the aperture in millimetres is the practical limit, and 3x reaches it quickly in smaller instruments. Pairing the extender with a longer eyepiece rather than a short one is how most observers keep it in useful territory.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. It goes into the 2-inch focuser or diagonal, and the eyepiece or camera adapter goes into it. Refocusing after fitting it is the only step, and there is nothing to align or adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow is this different from a Barlow?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA Barlow's amplification changes with the distance to the eyepiece, so its marked factor is only correct at one spacing. This is a telecentric design: the rays leave it parallel to the axis, so it stays at 3x whether the eyepiece is seated directly in it or sitting behind a diagonal.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThree times whatever the eyepiece gives on its own. A 24mm eyepiece in a 1000mm telescope gives 42x by itself and 125x through the extender.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it change eye relief?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo, and that is the point of using one. The eyepiece keeps its own eye relief and apparent field while behaving as a focal length three times shorter.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it work with 1.25-inch eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, using a 2-inch to 1.25-inch adapter in the top of it. The extender itself needs a 2-inch focuser or diagonal to sit in.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 2-inch telecentric 3x focal extender with EMD coatings and blackened element edges, holding its amplification constant regardless of spacing and leaving the eyepiece's eye relief untouched. If you would like to know which of your eyepieces will still be useful behind it on your telescope, send us the focal length and aperture and we will run the numbers for you.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013457834095,"sku":"FE03-020","price":249.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FE03-020_1_1663x__55386.jpg?v=1766553521"},{"product_id":"m42-m42-extender-21mm-length","title":"M42-M42 extender (21mm length )","description":"\u003cspan style=\"font-family: Arial;\"\u003eZWO 21mm Extension ring.  M42 male and female threads.\u003c\/span\u003e","brand":"ZWO","offers":[{"title":"Default Title","offer_id":44013503807599,"sku":"ZWO-EXT-21","price":25.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/21mmExtend-1024x853__18315.jpg?v=1766554504"},{"product_id":"william-optics-54mm-flattener-extender-for-gt81-wifd","title":"William Optics 54mm Flattener Extender for GT81 WIFD","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics 54mm Flattener Extender for GT81 WIFD\u003c\/strong\u003e is a spacing adapter used to connect compatible William Optics flatteners and reducers to the Gran Turismo 81 WIFD imaging system.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using a GT81 WIFD who need the correct extension spacing for their flattener or reducer setup.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDedicated spacing adapter:\u003c\/strong\u003e Helps complete the correct imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGT81 WIFD compatibility:\u003c\/strong\u003e Designed for the William Optics GT81 WIFD system.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAstrophotography use:\u003c\/strong\u003e Supports proper camera spacing and field correction.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eGT81 WIFD flattener\/reducer setups\u003c\/li\u003e\n\u003cli\u003eDeep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eCamera spacing and adapter configuration\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your exact telescope, flattener, reducer, and camera-side thread requirements before purchase.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is a mechanical adapter only. It does not provide optical correction by itself.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose this adapter when your GT81 WIFD imaging train requires the 54mm flattener extender shown in the William Optics compatibility table.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154247999599,"sku":"M80-54-M48","price":95.2,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-54mm-flattener-extender-gt81-wifd.jpg?v=1779655062"},{"product_id":"william-optics-45mm-flattener-extender","title":"William Optics 45mm Flattener Extender","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics 45mm Flattener Extender\u003c\/strong\u003e is a mechanical extension adapter used to achieve the required spacing between compatible William Optics refractors, flatteners\/reducers, and camera systems.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers configuring a William Optics imaging train that requires a 45mm extension adapter for the correct flattener or reducer spacing.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e45mm extension:\u003c\/strong\u003e Helps achieve proper mechanical spacing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAstrophotography setup support:\u003c\/strong\u003e Useful when configuring flatteners, reducers, and camera adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWilliam Optics compatibility:\u003c\/strong\u003e Designed for compatible WO imaging systems.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFlattener\/reducer spacing\u003c\/li\u003e\n\u003cli\u003eCamera train setup\u003c\/li\u003e\n\u003cli\u003eDeep-sky astrophotography accessories\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your exact telescope, flattener\/reducer, and camera thread requirements before purchase.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is a mechanical adapter only. It does not provide optical correction by itself.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose this adapter when your William Optics imaging train requires a 45mm spacing extension.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154248130671,"sku":"M80-45-M48","price":80.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-45mm-flattener-extender.jpg?v=1779655074"},{"product_id":"william-optics-4-inch-extender","title":"William Optics 4 inch Extender","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics 4 inch Extender\u003c\/strong\u003e is a mechanical extension adapter used to achieve the required spacing in compatible William Optics flattener, reducer, and astrophotography camera setups.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers who need a longer mechanical extension to complete a William Optics imaging train.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e4 inch extension:\u003c\/strong\u003e Provides additional spacing for compatible imaging configurations.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlattener\/reducer support:\u003c\/strong\u003e Helps achieve correct mechanical spacing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAstrophotography accessory:\u003c\/strong\u003e Useful for camera train setup and backfocus configuration.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eCamera spacing\u003c\/li\u003e\n\u003cli\u003eReducer\/flattener setup\u003c\/li\u003e\n\u003cli\u003eDeep-sky astrophotography imaging trains\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your telescope, flattener\/reducer, camera adapter, and thread requirements before purchase.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is a mechanical extension only. It does not provide optical correction by itself.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the William Optics 4 inch Extender when your compatible imaging train requires additional extension spacing.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154252488815,"sku":"P-M92EX","price":111.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-4-inch-extender.jpg?v=1779655131"},{"product_id":"takahashi-rd-aux-ring-extender-for-mewlon-300","title":"Takahashi RD Aux Ring Extender for Mewlon-300","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe RD Aux Ring Extender is a 38 mm M72 extension sleeve built for the Mewlon-300CR and Mewlon-300CRS. It sits in the imaging train alongside reducer and extender accessories, and threads to any other Takahashi telescope carrying the same M72 interface.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is what you need if you own a Mewlon-300CR or Mewlon-300CRS and your reducer or extender train needs an additional 38 mm of M72-threaded spacing.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eM72 thread:\u003c\/strong\u003e Takahashi's standard interface for the Mewlon-300 imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e38 mm length:\u003c\/strong\u003e the extension it adds to your reducer or extender stack.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCross-compatible:\u003c\/strong\u003e fits any Takahashi telescope using the same M72 thread, not only the Mewlon-300.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e\n\u003cstrong\u003eBuilding out a reducer or extender train on the Mewlon-300CR or 300CRS\u003c\/strong\u003e where an extra 38 mm of M72 spacing is needed.\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIf you're planning a full imaging train and want the spacing confirmed before you order, send us your reducer or extender and we'll work it out with you. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for published telescope back focus figures.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it threads directly into the M72 imaging train with no adjustment required.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it fit telescopes other than the Mewlon-300?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes, any Takahashi telescope using the same M72 thread standard.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need this for a standard Mewlon-300 setup?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eOnly if your reducer or extender combination needs the extra 38 mm of spacing. Send us your imaging train and we will confirm whether it applies.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 38 mm, M72-threaded extension ring for the Mewlon-300CR and 300CRS reducer\/extender train.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047109316719,"sku":"TAK-TKA83205","price":143.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/takahashi-extension-tube-m72-for-mewlon-crs-tka83205-astronomy-plus-1.jpg?v=1786913899"},{"product_id":"takahashi-extender-c2x-extender","title":"Takahashi Extender-C2X Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Extender-C2X extends focal length on the FS-60CB, FC-76D and FC-100D. Takahashi's own naming — the \"C2X\" designation — follows the same convention as its other 2x extenders, and the part is built to lengthen the focal length of these doublets without adding measurable aberration of its own.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is what you need if you own an FS-60CB, FC-76D or FC-100D and want to reach a longer effective focal length for tighter framing — small planetary nebulae, galaxies, or lunar and planetary detail — without changing telescopes.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eAn extender lengthens the light path between the objective and the focal plane, which increases effective focal length and focal ratio without touching the objective itself. Takahashi builds its extenders to add that length while holding the telescope's own correction, rather than introducing new aberration the objective wasn't designed for — the same principle behind the \u003ca href=\"\/products\/takahashi-ortho-extender-2x-barlow\"\u003eOrtho Extender 2x Barlow\u003c\/a\u003e used elsewhere in the line.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTighter framing on small targets\u003c\/strong\u003e — planetary nebulae, small galaxies, lunar and planetary detail — on the FS-60CB, FC-76D or FC-100D.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtending an existing FC or FS doublet\u003c\/strong\u003e rather than buying a longer-focal-length telescope.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Extender-C2X is matched to the FS-60CB, FC-76D and FC-100D. If you want to confirm it fits your specific imaging train before ordering, send us your telescope and camera and we will work it out with you.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt fits into the imaging train on the FS-60CB, FC-76D or FC-100D the same way any extender does — in line between the telescope and camera. Send us your setup and we will confirm the exact fit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eReaching a longer effective focal length on a small FC or FS doublet for tighter framing on small targets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt is built for the photographic train on these telescopes; if you want to use it visually, send us your eyepiece setup and we will confirm the fit.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a focal-length extender for the FS-60CB, FC-76D and FC-100D, built to lengthen the light path without adding aberration of its own.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047109447791,"sku":"TAK-TKA00594","price":154.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/TKA00594_1.jpg?v=1786913952"},{"product_id":"takahashi-epsilon-130d-1-5x-extender","title":"Takahashi Epsilon-130D 1.5x Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Epsilon Extender 1.5x E-130D extends the Epsilon-130D astrograph's native 430mm f\/3.3 to 650mm f\/5.0, while carrying the same coma correction that makes the Epsilon series sharp to the edge of frame at prime focus. Seven elements in five groups do the work of both magnifying the image and holding coma in check at the same time.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis extender suits Epsilon-130D owners who want a longer working focal length for tighter deep-sky targets — galaxies, planetary nebulae, small clusters — without switching to a slower, narrower-field telescope. It keeps the fast, coma-corrected imaging the Epsilon series is built for, just at 650mm instead of 430mm.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e7 elements in 5 groups:\u003c\/strong\u003e a full optical assembly, not a simple magnifying lens, that maintains coma correction at the extended focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.5x extension:\u003c\/strong\u003e takes the Epsilon-130D from 430mm f\/3.3 to 650mm f\/5.0.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eΦ44mm corrected image circle:\u003c\/strong\u003e diffraction-limited performance, about 2 microns at the center and up to 8 microns at the edge of a full-frame sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM60 input \/ M54 output threads:\u003c\/strong\u003e matches the Epsilon-130D's camera angle adjuster on one side and standard M54 camera adapters on the other.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe extender's seven-element, five-group design re-corrects coma at the longer focal length rather than simply magnifying the uncorrected image the way a basic Barlow would. Back focus is 56.2mm, the same figure the Epsilon-130D uses at prime focus, so an existing spacing setup carries over. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for the full chain.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eImaging smaller deep-sky targets — planetary nebulae, compact galaxies, globular clusters — that are undersized in the Epsilon-130D's native 430mm field; narrowband imaging where the extra focal length helps frame a target more tightly; general astrophotography where 650mm f\/5.0 suits the target better than 430mm f\/3.3.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eResulting focal length\u003c\/th\u003e\n\u003cth\u003eResulting focal ratio\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEpsilon-130D\u003c\/td\u003e\n\u003ctd\u003e650mm\u003c\/td\u003e\n\u003ctd\u003ef\/5.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e56.2mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe extender is specific to the Epsilon-130D — the Epsilon-160ED and Epsilon-180ED each use their own dedicated 1.5x extender, matched to their own thread sizes and back focus.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eScrew-in 2\" filters aren't recommended\u003c\/strong\u003e with this extender, since Takahashi notes they can introduce reflections at this focal ratio — a filter wheel or camera-side filter mounting avoids the issue.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAt 450g,\u003c\/strong\u003e it's light enough that it's the camera and filter wheel on the other end of the train, not the extender itself, that will drive your balance point.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it installs between the Epsilon-130D's camera angle adjuster and your camera on M60 and M54 threads, and the 56.2mm back focus matches the telescope's native prime-focus figure.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eImaging deep-sky targets that need more reach than the Epsilon-130D's native 430mm provides, while keeping the coma correction the Epsilon series is known for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt's built as an imaging accessory — the corrected image circle and mechanical interfaces are designed around camera sensors rather than eyepieces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat else do I need with it?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYour camera's own T-ring or M54 adapter to complete the connection at the 56.2mm back focus figure.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eA coma-corrected 1.5x extender that takes the Epsilon-130D to 650mm at f\/5.0 across a Φ44mm image circle, at the same 56.2mm back focus the telescope already uses at prime focus.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047111938159,"sku":"TAK-TKA69595","price":1269.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka69595_3.jpg?v=1786913997"},{"product_id":"takahashi-epsilon-160ed-1-5x-extender","title":"Takahashi Epsilon-160ED 1.5x Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Epsilon Extender 1.5x E-160ED extends the Epsilon-160ED astrograph's native 530mm f\/3.3 to 800mm f\/5.0, carrying the coma correction the Epsilon series is built around through to the longer focal length. Seven elements in five groups do the magnifying and the correcting together, rather than adding pure magnification on top of an uncorrected image.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis extender suits Epsilon-160ED owners who want more reach for tighter deep-sky targets — galaxies, planetary nebulae, compact clusters — while keeping the fast, coma-corrected imaging the Epsilon-160ED is built for. Takahashi rates the native Epsilon-160ED at an RMS spot radius within 1.3 microns across a full-frame field; the extender is built to preserve that standard at 800mm.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e7 elements in 5 groups:\u003c\/strong\u003e a complete optical assembly that maintains coma correction at the extended focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.5x extension:\u003c\/strong\u003e takes the Epsilon-160ED from 530mm f\/3.3 to 800mm f\/5.0.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eΦ44mm corrected image circle:\u003c\/strong\u003e diffraction-limited performance, roughly 2 microns at center and up to 8 microns at the edge of a full-frame sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMatched thread interfaces:\u003c\/strong\u003e installs between the Epsilon-160ED's camera angle adjuster and a standard camera adapter.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eBack focus with the extender in place is 56.2mm — the same figure the Epsilon-160ED uses at prime focus — so an existing spacing setup carries over directly. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for the full spacing chain.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eImaging smaller deep-sky targets that are undersized in the Epsilon-160ED's native 530mm field; narrowband and high-resolution work where the extra reach helps frame a target tightly; general astrophotography where 800mm f\/5.0 suits the target better than 530mm f\/3.3.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eResulting focal length\u003c\/th\u003e\n\u003cth\u003eResulting focal ratio\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEpsilon-160ED\u003c\/td\u003e\n\u003ctd\u003e800mm\u003c\/td\u003e\n\u003ctd\u003ef\/5.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e56.2mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe extender is specific to the Epsilon-160ED — the Epsilon-130D and Epsilon-180ED each use their own dedicated 1.5x extender, sized for their own thread interfaces.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eScrew-in 2\" filters aren't recommended\u003c\/strong\u003e with this extender, as Takahashi notes they can introduce reflections at this focal ratio — a filter wheel or camera-side filter mounting avoids the issue.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it installs between the Epsilon-160ED's camera angle adjuster and your camera, and the 56.2mm back focus matches the telescope's native prime-focus figure.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eImaging deep-sky targets that need more reach than the Epsilon-160ED's native 530mm provides, while keeping the coma correction the Epsilon series is known for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt's built as an imaging accessory — the corrected image circle and mechanical interfaces are designed around camera sensors rather than eyepieces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat else do I need with it?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYour camera's own T-ring or adapter to complete the connection at the 56.2mm back focus figure.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eA coma-corrected 1.5x extender that takes the Epsilon-160ED to 800mm at f\/5.0 across a Φ44mm image circle, at the same 56.2mm back focus the telescope already uses at prime focus.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047112134767,"sku":"TAK-TKA59595","price":1382.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/e-ext160ed_320x_9bf13e78-a41f-4129-a430-649bd1c0e8cd.jpg?v=1786914025"},{"product_id":"takahashi-epsilon-180ed-1-5x-extender","title":"Takahashi Epsilon-180ED 1.5x Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Epsilon Extender 1.5x E-180ED extends the Epsilon-180ED astrograph's native 500mm f\/2.8 to 780mm f\/4.3, carrying the Epsilon series' coma correction through to the longer focal length. Seven elements in five groups magnify and re-correct the image together, holding the same fully-corrected Φ44mm circle the telescope delivers at prime focus.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis extender suits Epsilon-180ED owners who want more reach for tighter deep-sky targets — galaxies, planetary nebulae, compact clusters — while keeping the fast, coma-corrected imaging the Epsilon-180ED is built for.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e7 elements in 5 groups:\u003c\/strong\u003e a complete optical assembly that maintains coma correction at the extended focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.5x extension:\u003c\/strong\u003e takes the Epsilon-180ED from 500mm f\/2.8 to 780mm f\/4.3.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eΦ44mm corrected image circle:\u003c\/strong\u003e fully corrected for coma, suited to full-frame sensors.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM68 input \/ M54 output threads:\u003c\/strong\u003e installs between the Epsilon-180ED's camera angle adjuster and a standard camera adapter.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eBack focus with the extender in place is 56.2mm, the same figure the Epsilon-180ED uses at prime focus, so an existing spacing setup carries over directly. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for the full spacing chain.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eImaging smaller deep-sky targets that are undersized in the Epsilon-180ED's native 500mm field; narrowband and high-resolution imaging where the extra reach helps frame a target tightly; general astrophotography where 780mm f\/4.3 suits the target better than 500mm f\/2.8.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eResulting focal length\u003c\/th\u003e\n\u003cth\u003eResulting focal ratio\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEpsilon-180ED\u003c\/td\u003e\n\u003ctd\u003e780mm\u003c\/td\u003e\n\u003ctd\u003ef\/4.3\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e56.2mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe extender is specific to the Epsilon-180ED — the Epsilon-130D and Epsilon-160ED each use their own dedicated 1.5x extender, sized for their own thread interfaces.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eFilters mount at the camera, not on the extender:\u003c\/strong\u003e Takahashi recommends against screw-in 2\" filters here, so a filter wheel or camera-side filter mount is the way to add narrowband or broadband filtration.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAt 550g,\u003c\/strong\u003e it's a modest addition to the imaging train — worth noting once your camera and filter wheel are attached, but not a figure that will drive your balance point on its own.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it installs between the Epsilon-180ED's camera angle adjuster and your camera on M68 and M54 threads, and the 56.2mm back focus matches the telescope's native prime-focus figure.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eImaging deep-sky targets that need more reach than the Epsilon-180ED's native 500mm provides, while keeping the coma correction the Epsilon series is known for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt's built as an imaging accessory — the corrected image circle and mechanical interfaces are designed around camera sensors rather than eyepieces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat else do I need with it?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYour camera's own T-ring or M54 adapter to complete the connection at the 56.2mm back focus figure.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eA coma-corrected 1.5x extender that takes the Epsilon-180ED to 780mm at f\/4.3 across a Φ44mm image circle, at the same 56.2mm back focus the telescope already uses at prime focus.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047112593519,"sku":"TAK-TKA68595","price":1425.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka68595_3.jpg?v=1786914054"},{"product_id":"takahashi-1-7x-cq-extender-module-for-fs-60q-refractor","title":"Takahashi EX CQ 1.7x Extender for FS-60CB (FS-60Q Conversion)","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe EX CQ 1.7x Extender installs between the focuser and the FS-60CB's fluorite doublet objective, converting the tube's optics to the same 600 mm f\/10.0 configuration published for the FS-60Q. It threads in place with an M55.9 mount and flattens the image circle to 44 mm at the same time as it extends the focal length.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you already own the FS-60CB and want the FS-60Q's longer reach — for solar eclipse photography, lunar and planetary imaging, and higher-magnification visual use — without buying a second optical tube.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eConverts FS-60CB to FS-60Q spec:\u003c\/strong\u003e 355mm f\/5.9 becomes 600mm f\/10.0, matching Takahashi's own FS-60Q optical tube.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e44mm flattened image circle:\u003c\/strong\u003e the extended path is corrected at the same time it is lengthened.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstalls between focuser and tube:\u003c\/strong\u003e a permanent-feeling but removable module rather than a drawtube accessory.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOpens up reducer options:\u003c\/strong\u003e Takahashi notes the resulting f\/10 system can be brought back down toward f\/6.2 or f\/4.2 with the matching reducers.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FS-60 platform ships as a 355mm f\/5.9 fluorite doublet in CB form. The EX CQ 1.7x sits ahead of the focuser and behind the objective, changing the light path so the whole system performs exactly as Takahashi's dedicated FS-60Q tube does — 600mm at f\/10.0, with the image circle flattened to 44mm and a published back focus of 158.4mm from the rear of the module.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eSolar eclipse and transit photography at longer focal length, lunar and planetary imaging, and higher-power visual observing on a compact 60mm platform.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this pairing for the FS-60CB specifically.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith EX CQ1.7x\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFS-60CB\u003c\/td\u003e\n\u003ctd\u003e355mm f\/5.9\u003c\/td\u003e\n\u003ctd\u003e600mm f\/10.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e158.4mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe resulting figures match Takahashi's own FS-60Q optical tube exactly, so accessories rated for the FS-60Q's back focus generally carry over. Full spacing guidance is in the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIt replaces the CB configuration rather than sitting alongside it:\u003c\/strong\u003e once installed, the tube runs at f\/10.0 until the module is removed.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it installs as a single module between the focuser and the objective cell, with no separate spacing to calculate for the base configuration.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eExtending the FS-60CB's reach for solar, lunar, and planetary work at f\/10.0.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this make my FS-60CB an FS-60Q?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eOptically, yes — the resulting focal length, ratio, image circle, and back focus match Takahashi's FS-60Q tube exactly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I reduce the focal ratio back down afterward?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTakahashi notes the resulting f\/10 system pairs with its own reducers to bring the ratio back toward f\/6.2 or f\/4.2 — send us your imaging setup and we will confirm the right one.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe EX CQ 1.7x Extender turns an FS-60CB into the optical equivalent of Takahashi's FS-60Q — 600mm at f\/10.0 with a 44mm flattened image circle and 158.4mm of back focus.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047116394607,"sku":"TAK-TKA20595","price":531.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tfk6004qm_1_2_6.jpg?v=1786914166"},{"product_id":"teq0001-extender-q-1-6x-extender-for-takahashi-fsq-106","title":"Takahashi Extender-Q 1.6X for FSQ-106 (Fluorite) and Sky-90","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Extender-Q is a five-element 1.6x tele-extender built for Takahashi's original fluorite FSQ-106 and Sky-90 Petzval refractors. Screwed into the focuser drawtube, it works as a 1.6x visual Barlow and as a photographic and CCD tele-extender, accepting standard 1.25-inch eyepieces and diagonals, with internal threading for filters and an optional upgrade path to 2-inch accessories.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you own the original fluorite FSQ-106 or a Sky-90 and want more focal length for lunar, planetary, or small-target imaging, or higher-power visual observing, from a telescope you already own.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFive-element optical design:\u003c\/strong\u003e functions as both a 1.6x visual Barlow and a photographic tele-extender.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25-inch accessory compatibility:\u003c\/strong\u003e accepts standard eyepieces and diagonals, with an internal filter thread.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2-inch upgrade path:\u003c\/strong\u003e an optional adapter extends compatibility to 2-inch accessories.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDirect drawtube mount:\u003c\/strong\u003e screws straight into the focuser, no separate adapter required on the FSQ-106 or Sky-90.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis extender serves the earlier fluorite FSQ-106 and the Sky-90 rather than the current FSQ-106EDX4. On the fluorite FSQ-106 it brings the focal ratio from f\/5 to f\/8; on the Sky-90, from f\/5.56 to f\/8.9. Takahashi publishes the resulting focal ratios for both pairings.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eHigher-magnification lunar and planetary imaging and visual observing on an original fluorite FSQ-106 or Sky-90.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is the extender for the \u003cstrong\u003eoriginal fluorite FSQ-106 and Sky-90\u003c\/strong\u003e — both earlier Takahashi models. It is explicitly \u003cstrong\u003enot compatible with the current FSQ-106EDX4\u003c\/strong\u003e (\"New Q\"); that telescope uses the separate Extender-QE 1.6x, which Ontario Telescope also carries. If you are not sure which FSQ-106 generation you own, send us the tube's markings or serial plate and we will confirm the right extender. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for general spacing reference.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot for the FSQ-106EDX4:\u003c\/strong\u003e the current \"New Q\" telescope requires the Extender-QE 1.6x instead of this part.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it screws directly into the focuser drawtube on the FSQ-106 or Sky-90, with no separate adapter needed for the base 1.25-inch configuration.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eHigher-power lunar, planetary, and visual work on the original fluorite FSQ-106 or Sky-90.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this fit my FSQ-106EDX4?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — the FSQ-106EDX4 uses the Extender-QE 1.6x, a different part built for the New Q's 2-inch focuser and 44mm image circle.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it for imaging as well as visual?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — Takahashi describes it as both a visual Barlow and a photographic tele-extender.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Extender-Q 1.6x is the matched tele-extender for the original fluorite FSQ-106 and Sky-90, bringing both to roughly f\/8 for higher-power imaging and visual work, with an eyepiece-ready 1.25-inch interface and an optional path to 2-inch accessories.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047118983279,"sku":"TAK-TKA00595","price":682.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/teq0001_1_2_5.jpg?v=1786914282"},{"product_id":"texdx0001-fsq-85-extender-ed","title":"Takahashi EX ED 1.5x Extender for FSQ-85EDX","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe EX ED 1.5x is a 2-inch barrel extender built around extra-low-dispersion glass for the FSQ-85EDX, Takahashi's BabyQ Petzval astrograph. It brings the native 450mm f\/5.3 up to 680mm f\/8.0 while holding a 44mm corrected image circle, functioning as both a magnifying Barlow for visual use and a tele-extender for imaging.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you own the FSQ-85EDX and want tighter framing on smaller deep-sky targets — planetary nebulae, galaxies, globular clusters — than the astrograph's native wide field delivers, without losing the ED-corrected color performance.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eED glass element:\u003c\/strong\u003e extra-low-dispersion glass controls chromatic aberration through the extended path.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.5x magnification:\u003c\/strong\u003e 450mm f\/5.3 becomes 680mm f\/8.0 on the FSQ-85EDX.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e44mm image circle held constant:\u003c\/strong\u003e the extended focal length stays corrected rather than trading correction for reach.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2-inch barrel interface:\u003c\/strong\u003e mounts directly to the FSQ-85EDX's 2-inch drawtube and doubles as a visual Barlow.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FSQ-85EDX's four-element Petzval design is corrected natively at 450mm f\/5.3 for wide-field framing. The EX ED 1.5x adds a low-dispersion element ahead of the focuser to extend the focal length to 680mm at f\/8.0 while holding the 44mm image circle and 117.5mm back focus that the astrograph is designed around, rather than simply magnifying and letting the corners degrade.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTighter deep-sky framing on the FSQ-85EDX — small galaxies, planetary nebulae, and globular clusters — and higher-magnification visual or lunar\/planetary use when stacked with the TOA-35FL flattener on a TSA-120, TOA-130NS\/NFB, or TOA-150B.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this extender on its own for the FSQ-85EDX, and stacked with the TOA-35FL flattener for three additional telescopes.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eConfiguration\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eResulting\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFSQ-85EDX (alone)\u003c\/td\u003e\n\u003ctd\u003e450mm f\/5.3\u003c\/td\u003e\n\u003ctd\u003e680mm f\/8.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTSA-120 + TOA-35FL\u003c\/td\u003e\n\u003ctd\u003e900mm f\/7.5\u003c\/td\u003e\n\u003ctd\u003e1350mm f\/11.3\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTOA-130NS\/NFB + TOA-35FL\u003c\/td\u003e\n\u003ctd\u003e1000mm f\/7.7\u003c\/td\u003e\n\u003ctd\u003e1500mm f\/11.5\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTOA-150B + TOA-35FL\u003c\/td\u003e\n\u003ctd\u003e1100mm f\/7.3\u003c\/td\u003e\n\u003ctd\u003e1650mm f\/11.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eFor the stacked configurations, the TOA-35FL flattener is a separate part Ontario Telescope also carries. Full spacing detail is in the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eStacked use needs the TOA-35FL separately:\u003c\/strong\u003e the TSA-120\/TOA-130\/TOA-150B figures above require both parts together, not this extender alone.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it threads onto the FSQ-85EDX's 2-inch drawtube directly, with the 117.5mm back focus fixed by the unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTighter deep-sky framing on the FSQ-85EDX, and longer-focal-length imaging on TOA\/TSA triplets when paired with the TOA-35FL.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work as a visual Barlow too?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — the same 2-inch barrel design functions as a 1.5x magnifier for eyepiece use.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it on my TOA-130 without the TOA-35FL?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTakahashi's published figures for the TOA\/TSA telescopes are for the extender stacked with the TOA-35FL flattener; send us your setup and we will confirm what the pairing does for your specific train.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe EX ED 1.5x brings the FSQ-85EDX to 680mm at f\/8.0 with its 44mm image circle intact, and extends further reach to the TSA-120 and TOA-130\/150B line when stacked with the TOA-35FL flattener.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047119310959,"sku":"TAK-TKA37595","price":687.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/texdx0001_4_2_6.jpg?v=1786914324"},{"product_id":"mcr0015-mewlon-cr-extender-1-5x","title":"Takahashi Mewlon CR Extender 1.5x","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Mewlon CR Extender 1.5x is Takahashi's magnifying extender for the CCA-250 and the Mewlon-250CRS and Mewlon-300CRS Cassegrains. Depending on the host telescope it stretches the native focal length by roughly 1.5x, reaching as far as f\/15.1 on the Mewlon-250CRS for high-resolution planetary and lunar work.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you own a CCA-250, Mewlon-250CRS, or Mewlon-300CRS and want the longest reach those telescopes can offer — high-resolution lunar and planetary imaging, or high-power visual observing, beyond their already long native focal ratios.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eShared across three telescopes:\u003c\/strong\u003e one part, with the resulting focal length and ratio set by which Cassegrain it is mounted on.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e44mm image circle\u003c\/strong\u003e on the Mewlon-250CRS and Mewlon-300CRS; 40mm on the CCA-250.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e117.5mm back focus\u003c\/strong\u003e held constant across all three telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLong-ratio result:\u003c\/strong\u003e from f\/7.5 on the CCA-250 up to f\/15.1 on the Mewlon-250CRS.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe CCA-250, Mewlon-250CRS, and Mewlon-300CRS are already long-focus Cassegrain designs; the EX CR1.5x extends each further rather than correcting or reducing. Because the multiplier interacts with the native focal ratio of each telescope, the resulting f-ratio differs meaningfully across the line — f\/7.5 on the CCA-250's faster native f\/5.0, up to f\/15.1 on the Mewlon-250CRS's f\/10.0 — while the back focus stays fixed at 117.5mm on all three.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging, and double-star and high-power visual observing, on the CCA-250, Mewlon-250CRS, or Mewlon-300CRS.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this extender for three telescopes.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith EX CR1.5x\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCCA-250\u003c\/td\u003e\n\u003ctd\u003e1250mm f\/5.0\u003c\/td\u003e\n\u003ctd\u003e1880mm f\/7.5\u003c\/td\u003e\n\u003ctd\u003eΦ40mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMewlon-250CRS\u003c\/td\u003e\n\u003ctd\u003e2500mm f\/10.0\u003c\/td\u003e\n\u003ctd\u003e3780mm f\/15.1\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMewlon-300CRS\u003c\/td\u003e\n\u003ctd\u003e2960mm f\/9.9\u003c\/td\u003e\n\u003ctd\u003e4475mm f\/14.9\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe same three telescopes also take the companion Reducer-CR 0.73x, which Ontario Telescope carries separately, for the opposite trade-off. Spacing detail is in the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eLong focal ratios reduce image brightness per unit time:\u003c\/strong\u003e f\/15.1 on the Mewlon-250CRS trades exposure speed for resolution, which suits planetary lucky-imaging more than faint deep-sky targets.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it threads to the rear cell with a fixed 117.5mm back focus on all three host telescopes, so there is no spacing to work out.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging, and high-power visual observing, on the CCA-250 or Mewlon CRS line.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the same part fit all three telescopes?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — one extender, with a different resulting focal length and ratio depending on the host.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs there an opposite option for wider fields?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — the Reducer-CR 0.73x fits the same three telescopes and reduces rather than extends; send us your target list and we can help you pick between them.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Mewlon CR Extender 1.5x stretches the CCA-250, Mewlon-250CRS, and Mewlon-300CRS to their longest published focal ratios — up to f\/15.1 — for high-resolution lunar and planetary work.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047119605871,"sku":"TAK-TKA82595","price":687.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka82595_2_6.jpg?v=1786914378"},{"product_id":"takahashi-extender-qe-1-6x-2-field-flattener","title":"Takahashi Extender-QE 1.6x 2\" Field Flattener for FSQ-106EDX4","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Extender-QE 1.6x is the five-element 2-inch extender built specifically for Takahashi's current FSQ-106EDX4 (\"New Q\") refractor, also published for the FSQ-130ED. It brings the FSQ-106EDX4's native 530mm f\/5.0 up to 850mm f\/8.0 while holding a flat, colour-corrected 44mm image circle, and doubles as a high-magnification visual accessory.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you own an FSQ-106EDX4 or FSQ-130ED and want tighter framing on small deep-sky targets than the astrograph's native wide field delivers, or higher-power lunar and planetary views without switching telescopes.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFive-element optical design:\u003c\/strong\u003e delivers a flat, colour-corrected, high-contrast image at the extended focal length rather than a simple magnifier.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.6x extension:\u003c\/strong\u003e 530mm f\/5.0 becomes 850mm f\/8.0 on the FSQ-106EDX4.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e44mm image circle held constant\u003c\/strong\u003e at the extended focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSecure mounting features:\u003c\/strong\u003e an anti-slip groove and dual thumbscrews keep the extender seated through the imaging or visual session.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics\u003c\/strong\u003e for high-contrast imaging and visual use alike.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eBuilt for the FSQ-106EDX4's New Q focuser, the Extender-QE 1.6x uses a five-element design rather than a simple Barlow doublet, which is why the image circle stays a corrected 44mm at the extended 850mm f\/8.0 rather than degrading toward the edges the way a plain magnifier would. Takahashi also publishes the same part for the FSQ-130ED, where it extends 650mm f\/5.0 to 1040mm f\/8.0.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTighter deep-sky framing on the FSQ-106EDX4 or FSQ-130ED, plus higher-magnification lunar and planetary visual observing without short-eye-relief eyepieces.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this extender for two current telescopes.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith Extender-QE 1.6x\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFSQ-106EDX4 (New Q)\u003c\/td\u003e\n\u003ctd\u003e530mm f\/5.0\u003c\/td\u003e\n\u003ctd\u003e850mm f\/8.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFSQ-130ED\u003c\/td\u003e\n\u003ctd\u003e650mm f\/5.0\u003c\/td\u003e\n\u003ctd\u003e1040mm f\/8.0\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThis is the part for the current FSQ-106EDX4; the earlier fluorite FSQ-106 and Sky-90 use the separate Extender-Q 1.6x, also carried by Ontario Telescope. For spacing your full imaging train, see the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot the same part as the original Extender-Q:\u003c\/strong\u003e the earlier fluorite FSQ-106 and Sky-90 need the separate Extender-Q 1.6x rather than this one.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it seats into the 2-inch focuser with an anti-slip groove and dual thumbscrews, and the 117.5mm back focus is fixed by the unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTighter deep-sky framing and higher-power lunar\/planetary imaging on the FSQ-106EDX4 or FSQ-130ED.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this fit an older fluorite FSQ-106?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — that telescope uses the separate Extender-Q 1.6x. Send us your FSQ-106's markings if you are not certain which generation you have and we will confirm the right part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for visual observing as well as imaging?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — it functions as a high-magnification visual accessory in addition to a photographic extender.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Extender-QE 1.6x extends the FSQ-106EDX4 to 850mm at f\/8.0 with a flat, colour-corrected 44mm image circle, and does the same for the FSQ-130ED at 1040mm f\/8.0.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047120752751,"sku":"TAK-TKA36595","price":762.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tsq0106qe_2_6.jpg?v=1786914418"},{"product_id":"takahashi-foa-60-extender-1-7xr","title":"Takahashi FOA-60 Extender 1.7XR","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FOA-60 Extender 1.7XR converts Takahashi's FOA-60 Ortho Apochromat to the same 900mm f\/15.0 configuration published for the dedicated FOA-60Q optical tube, with the image circle opening to 88mm and back focus extending to 208.1mm. It is built into the optical path the same way the FOA-60Q's factory objective is, rather than mounting on the drawtube as a Barlow would.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you already own the FOA-60 and want the FOA-60Q's long-focal-length performance — high-resolution lunar and planetary imaging and high-power visual observing — without buying a second optical tube.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eConverts FOA-60 to FOA-60Q spec:\u003c\/strong\u003e 530mm f\/8.8 becomes 900mm f\/15.0, matching Takahashi's own FOA-60Q tube exactly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e88mm image circle\u003c\/strong\u003e at the extended focal length, with 208.1mm back focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePreserves the FOA-60's correction:\u003c\/strong\u003e Takahashi states the resulting system holds a Strehl ratio above 99% across nearly the full visible spectrum.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSupports high magnification:\u003c\/strong\u003e Takahashi rates it for visual magnifications up to 300x while keeping the image clean.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FOA-60's 60mm fluorite doublet objective is built for correction quality over field width; the 1.7XR extender lengthens the light path to 900mm at f\/15.0 — identical to the factory FOA-60Q configuration — while the doublet's inherent correction keeps the Strehl ratio high through the extended path. This is the same route Takahashi uses to build the FOA-60Q itself, applied to an FOA-60 already in the field.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging, and high-magnification visual observing of the Moon, planets, and double stars, on an FOA-60.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this pairing for the FOA-60 specifically.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith EX 1.7xR\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFOA-60\u003c\/td\u003e\n\u003ctd\u003e530mm f\/8.8\u003c\/td\u003e\n\u003ctd\u003e900mm f\/15.0\u003c\/td\u003e\n\u003ctd\u003eΦ88mm\u003c\/td\u003e\n\u003ctd\u003e208.1mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe resulting figures match Takahashi's own FOA-60Q optical tube exactly. It is not combined with the FOA-60 0.93x Flattener, which serves the opposite, wide-field configuration of the same tube. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for general spacing reference.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot combined with the 0.93x Flattener:\u003c\/strong\u003e the two accessories serve opposite configurations of the FOA-60 and are not used together.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it installs into the optical path the same way the FOA-60Q's factory objective assembly does, with the resulting 208.1mm back focus fixed by the conversion.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging and high-power visual observing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this make my FOA-60 an FOA-60Q?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eOptically, yes — the resulting focal length, ratio, image circle, and back focus match Takahashi's FOA-60Q tube exactly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I still use the FOA-60 at its native focal length afterward?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe extender is a conversion rather than a drop-in accessory; if you want to switch back and forth between native and extended configurations, send us your setup and we will confirm what that involves.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FOA-60 Extender 1.7XR turns an FOA-60 into the optical equivalent of Takahashi's FOA-60Q — 900mm at f\/15.0 with an 88mm image circle and 208.1mm of back focus, for high-resolution lunar and planetary work.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047122686063,"sku":"TAK-TKA28595","price":818.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/TKA28595_1.jpg?v=1786914498"}],"url":"https:\/\/ontariotelescope.com\/collections\/fr-focal-extenders.oembed","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}