{"title":"Explore Scientific FCD-100","description":"\u003cp\u003eThe Explore Scientific FCD-100 line, listed by aperture. Part of \u003ca href=\"\/collections\/explore-scientific-telescopes\"\u003eExplore Scientific Telescopes\u003c\/a\u003e.\u003c\/p\u003e","products":[{"product_id":"explore-scientific-127mm-fcd100-apo","title":"Explore Scientific FCD100 Series 127mm f\/7.5 Air-Spaced Triplet ED APO Refractor Telescope","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific FCD100 Series 127mm is a five-inch air-spaced triplet apochromatic refractor with a focal length of 952mm at f\/7.5. The objective is built around Hoya FCD100 extra-low-dispersion glass, and Explore Scientific publishes a limiting magnitude of 13 and a resolution of .9 arcsec for it. The tube is aluminium, finished in white, and measures 41.75″ (1060mm) with the dew shield extended, 33.25″ (849mm) with it retracted, over a 130mm outside diameter, at a published 18lb (8.2kg).\u003c\/p\u003e\n\u003cp\u003eIt is supplied as an optical tube assembly. The published package covers a 2.5-inch focuser rated to carry up to 10 lbs of imaging gear, an integrated retractable dew shield, a cradle ring with a carry handle, and a Vixen-style dovetail plate. Enhanced multi-layer coatings are applied to suppress aberrations. No mount and no eyepieces are listed in the vendor's package.\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\u003eDeep-sky imagers\u003c\/strong\u003e who want a five-inch refractor with a focuser rated for a real imaging train rather than a token one. The 10 lb focuser rating is the figure that matters when a cooled camera, filter wheel, off-axis guider and rotator are all hanging off the back.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh-power visual observers:\u003c\/strong\u003e at f\/7.5 and 952mm this is a long enough refractor to hold correction on the Moon, planets and double stars, with .9 arcsec of published resolution to work with.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers stepping up from an 80mm or 100mm ED tube\u003c\/strong\u003e who want more aperture without moving to a mirror system and the collimation and cool-down that comes with one. This is a good match if you already run a mount with headroom well above 18 lb.\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\u003e127mm air-spaced triplet objective:\u003c\/strong\u003e three elements in the objective cell, separated by air gaps rather than cemented.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHoya FCD100 ED glass:\u003c\/strong\u003e the low-dispersion element in the group, which is what pulls the design into apochromatic territory.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e952mm focal length at f\/7.5:\u003c\/strong\u003e a moderate focal ratio for an apochromat, which eases the correction burden on the objective and keeps the field better behaved than a very fast triplet.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.5-inch focuser rated to 10 lbs:\u003c\/strong\u003e a load rating Explore Scientific publishes specifically for imaging gear.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntegrated retractable dew shield:\u003c\/strong\u003e it slides back over the tube, which is where the 8.5-inch difference between the two published tube lengths comes from.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEnhanced multi-layer deposition coatings\u003c\/strong\u003e on the optical surfaces, applied to raise transmission and hold contrast.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA two-element achromat brings two wavelengths to a common focus and leaves a visible residual — the secondary spectrum — around bright objects. A three-element apochromat adds a degree of freedom: with one element made of extra-low-dispersion glass, the designer can bring three widely separated wavelengths to essentially the same focal plane instead of two. The practical result is that the violet and deep-red ends of the spectrum land close enough to the visual focus that colour fringing on Venus, Jupiter and the lunar limb stops being a feature of the view.\u003c\/p\u003e\n\u003cp\u003eFCD100 is the ED glass type in this objective. Its job is dispersion control: it bends the different wavelengths by more similar amounts than ordinary crown or flint glass does, so the two mating elements have less residual colour to correct. Air spacing rather than cementing gives the design six optical surfaces to shape instead of four, and it removes a cement layer as a thermal variable in a five-inch lens — a real consideration in a lens this size cooling down through an evening.\u003c\/p\u003e\n\u003cp\u003eExplore Scientific does not publish a corrected image circle or a backfocus distance for this tube, so those rows are absent from the specifications below rather than estimated. If you are assembling an imaging train, send us the camera and flattener you have in mind and we will work the spacing out with you.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eDeep-sky astrophotography on a suitably rated equatorial mount, with a flattener matched to your sensor.\u003c\/li\u003e\n\u003cli\u003eHigh-magnification visual work on the Moon, planets and double stars, where .9 arcsec of published resolution sets the ceiling.\u003c\/li\u003e\n\u003cli\u003eLunar and planetary imaging with a focal extender ahead of a planetary camera.\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\u003eMount:\u003c\/strong\u003e not included. The published tube weight is 18lb (8.2kg) bare, before a diagonal, finder, camera or eyepiece, so a mount rated comfortably above that is the sensible starting point — and more again for imaging, where tracking accuracy rather than raw capacity is the constraint.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDovetail:\u003c\/strong\u003e the supplied plate is Vixen-style, so it seats in any Vixen saddle and in the dual-format saddles that take both Vixen and Losmandy plates.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyepieces and diagonal:\u003c\/strong\u003e not listed in the published package. The 2.5-inch focuser takes 2-inch accessories with the appropriate adapter, and 2-inch is the format most observers build around at this focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e 952mm ÷ eyepiece focal length. A 30mm gives 32x, a 20mm gives 48x, a 9mm gives 106x, a 5mm gives 190x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocal extenders:\u003c\/strong\u003e a 2x extender takes the system to 1904mm at f\/15, which is planetary imaging territory in steady air.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging train:\u003c\/strong\u003e the 10 lb focuser rating covers most cooled-camera trains, and we can go through yours item by item if you would like a second opinion on the load.\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\u003eThis is an optical tube assembly, not a complete telescope.\u003c\/strong\u003e A mount, a tripod, a diagonal and at least one eyepiece are separate items. We put packages like this together regularly — tell us how you plan to use it and we will price the whole thing out.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a 41.75-inch tube with the dew shield extended.\u003c\/strong\u003e That length is worth measuring against your case, your car and your observing space before ordering; the shield retracts to bring the tube down to 33.25 inches for transport.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe published 18lb is the bare tube.\u003c\/strong\u003e Loaded with a diagonal, finder and a 2-inch eyepiece, or with a full imaging train, it sits meaningfully higher, which is why mount headroom matters more than a bare-minimum rating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo corrected image circle or backfocus figure is published\u003c\/strong\u003e for this tube, so we quote neither. Send us your camera and we will tell you what we can establish about the spacing.\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\u003eThe optics need nothing from you — a refractor holds its collimation, so the tube is ready the moment it is on the mount. The work is physical rather than technical: 18lb and nearly 42 inches is a two-handed lift onto a saddle, and it goes more smoothly with the mount already levelled and the counterweights roughly positioned first.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat mount does it need?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eOne with capacity well above the 18lb bare tube weight, since the diagonal, finder and eyepiece or camera all add to it. For imaging, the useful figure is usually around half a mount's visual rating. Tell us what you own and we will give you an honest read on whether it will carry this tube.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill I see false colour?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAn air-spaced triplet using FCD100 ED glass is built specifically to remove it. On the brightest targets at very high power some residual is inherent to any refracting design, but it is not the limiting factor in this telescope the way it is in an achromat.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it come with eyepieces or a diagonal?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNeither is listed in the vendor's published package. The tube arrives with its 2.5-inch focuser, dew shield, cradle ring and Vixen dovetail. We can supply a diagonal and a starting eyepiece set alongside it.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 127mm f\/7.5 air-spaced triplet apochromat on FCD100 ED glass, 952mm focal length, with a 2.5-inch focuser rated to 10 lbs of imaging gear, a retractable dew shield, a cradle ring with carry handle and a Vixen dovetail — five inches of low-maintenance refractor aperture that serves visual and photographic use equally. If you are matching it to a mount or planning the imaging train, send us the details and we will work through the fit with you before you order.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013369589871,"sku":"FCD100-127075-02","price":3464.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100_127mm_1__75589.jpg?v=1766551589"},{"product_id":"es-80mm-fcd100-apo","title":"Explore Scientific ED80-FCD100 80mm f\/6 Air-Spaced Triplet Refractor with 0.8x Focal Reducer","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific ED80-FCD100 is an 80mm air-spaced apochromatic triplet refractor with a native focal length of 480mm at f\/6, supplied here together with the ES-FR0.8x focal reducer. The centre element is HOYA FCD100 extra-low-dispersion glass, and the tube carries a 2.5-inch hexagonal focuser sized around camera loads rather than eyepieces alone.\u003c\/p\u003e\n\u003cp\u003eExplore Scientific publishes a limiting magnitude of 12 and a resolution of 1.45 arcsec for the 80mm objective. The tube is 18.5″ (475mm) long with the dew shield extended and 15″ (381mm) with it retracted, 85mm in outside diameter, and 7.5 lb (3.4 kg) on its own. A Vixen-pattern dovetail is fitted.\u003c\/p\u003e\n\u003cp\u003eWith the two-element 0.8x reducer in the train, the published 480mm becomes 384mm and f\/6 becomes f\/4.8 — a short, fast imaging system that reverts to a 480mm f\/6 visual refractor when the reducer comes out.\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\u003eWide-field deep-sky imagers:\u003c\/strong\u003e 384mm at f\/4.8 with the reducer fitted frames large emission regions and open clusters that a longer instrument crops.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers who value colour correction:\u003c\/strong\u003e an air-spaced triplet using FCD100 ED glass is aimed at bringing three wavelengths to a common focus rather than two.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnyone with a modest mount:\u003c\/strong\u003e at 7.5 lb (3.4 kg) bare, this tube asks far less of a mount than a six-inch refractor does. This is a good match if you already own a mount in the 20–30 lb class and want to use most of its capacity on payload rather than on the tube itself.\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\u003e80mm air-spaced triplet objective:\u003c\/strong\u003e three elements with air gaps between them, one of them HOYA FCD100 extra-low-dispersion glass.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e480mm focal length at f\/6:\u003c\/strong\u003e short enough for wide fields, long enough that a 6mm eyepiece still reaches 80x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.5-inch hexagonal focuser:\u003c\/strong\u003e the hexagonal drawtube form is used to resist the rotational flex that a heavy camera train imposes on a round drawtube.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eES-FR0.8x focal reducer included:\u003c\/strong\u003e two elements, 2-inch diameter, 0.8x reduction, with a 42mm T2 camera adapter plate and a barrel threaded for standard 2-inch filters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRetractable dew shield:\u003c\/strong\u003e 18.5″ (475mm) extended, 15″ (381mm) retracted.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e85mm tube diameter and 7.5 lb (3.4 kg) tube weight,\u003c\/strong\u003e on a Vixen-pattern dovetail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSupplied package:\u003c\/strong\u003e Explore Scientific lists the refractor, the 0.8x focal reducer, a 2-inch diagonal, extension tubes, a finder scope base, the dew shield and a dust cover.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA doublet achromat brings two wavelengths to a common focus. A triplet adds a third element and, with the right glass, brings a third wavelength in as well — which is what shortens the residual colour error that shows as a violet halo around bright stars and along the lunar limb. The FCD100 element is the one doing that work: extra-low-dispersion glass spreads wavelengths less as they pass through it, so the design has less colour to correct in the first place.\u003c\/p\u003e\n\u003cp\u003eAir spacing matters here as much as glass choice. Cementing elements together saves two optical surfaces but locks the spacing to whatever the cement layer does under temperature change, and it puts an adhesive in the light path of the objective. An air-spaced triplet gives the designer six surfaces to shape instead of four and leaves the spacings mechanical rather than chemical. The cost is one more pair of surfaces to coat and a slightly longer thermal settling time at the start of a session.\u003c\/p\u003e\n\u003cp\u003eThe 0.8x reducer is a two-element group that shortens the effective focal length from 480mm to 384mm and, because aperture is unchanged at 80mm, drops the focal ratio from f\/6 to f\/4.8. Faster focal ratio means more signal per pixel per unit time, a wider field on the same sensor, and tighter tolerance on the spacing between the reducer and the sensor. Explore Scientific publishes the reducer's element count, diameter, reduction factor and its 42mm T2 thread, and specifies a 2-inch filter thread in the barrel; they do not publish a backfocus distance or a corrected image circle for this combination, so neither figure appears in the table below.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eWide-field deep-sky imaging at 384mm f\/4.8 with the reducer in place.\u003c\/li\u003e\n\u003cli\u003eVisual observing at 480mm f\/6 — open clusters, large nebulae, the Milky Way star fields, lunar and planetary at moderate power.\u003c\/li\u003e\n\u003cli\u003eTravel and dark-site trips, where 15″ retracted and 7.5 lb make the difference between packing it and leaving it.\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\u003eMount:\u003c\/strong\u003e not included. The 7.5 lb (3.4 kg) tube weight is before the diagonal, finder, camera and any guiding hardware, so the loaded figure runs higher — a mount rated at 20 lb or more leaves useful headroom for imaging.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDovetail:\u003c\/strong\u003e the Vixen-pattern bar drops into any Vixen saddle, and into dual-fit saddles that take both Vixen and Losmandy plates.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera attachment:\u003c\/strong\u003e the reducer's adapter plate carries a 42mm thread for a T2 ring, so a T-ring for your camera body completes the connection.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e the reducer barrel is threaded for standard 2-inch filters, which places light-pollution and narrowband filters ahead of the camera.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyepieces:\u003c\/strong\u003e none supplied. At 480mm a 40mm eyepiece gives 12x, a 20mm gives 24x, a 14mm gives 34x and a 5.5mm gives 87x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpacing for imaging:\u003c\/strong\u003e Explore Scientific does not publish the reducer-to-sensor distance, so we are not going to quote one. Send us the camera and any filter drawer you plan to use and we will work the spacing out with you before you order.\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\u003eThis is an optical tube with a reducer, not a complete telescope.\u003c\/strong\u003e A mount, a tripod and at least one eyepiece or a camera are needed to put it to work. We can quote the whole package in one go if that is easier.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific publishes no backfocus or corrected image circle for the ES-FR0.8x on this tube.\u003c\/strong\u003e Those rows are absent from the specifications rather than estimated. If you are building an imaging train, tell us the camera and we will put the question to our Explore Scientific rep.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAn 80mm aperture has a ceiling.\u003c\/strong\u003e The published resolution is 1.45 arcsec and the limiting magnitude is 12; high-power planetary detail is not what an 80mm f\/6 is optimised for. It earns its keep across wide fields.\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\u003eThe telescope itself is straightforward. A refractor holds its alignment, so there is no collimation to perform — it is ready as soon as it is on the mount and the dew shield is extended. The part that takes thought is the imaging train: the reducer, any filter drawer and the camera need to sit at the correct spacing from one another, and that is a one-time measurement rather than a nightly task. At 7.5 lb it is a one-handed lift onto a saddle.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does the 0.8x reducer actually change?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt takes the native 480mm f\/6 down to 384mm f\/4.8. The field on a given sensor gets wider and the system collects more signal per pixel in the same exposure time. For visual use the reducer comes out and the scope runs at its native 480mm.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat mount does it need?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eOne rated comfortably above the loaded weight. The tube is 7.5 lb bare, and a camera, guide scope and diagonal push that up. For imaging, a mount in the 20–30 lb class gives the settling behaviour that short exposures depend on. Tell us what you have and we will give you a straight answer about whether it will carry this.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it come with eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. A 2-inch diagonal, extension tubes, a finder base, the dew shield and a dust cover are included; eyepieces are chosen to suit the observing you do.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: an 80mm f\/6 air-spaced triplet with HOYA FCD100 glass, a 2.5-inch hexagonal focuser and a Vixen dovetail, bundled with the two-element ES-FR0.8x reducer that turns 480mm f\/6 into 384mm f\/4.8 — a 7.5 lb tube that images wide and observes cleanly. If you are matching it to a mount or a camera you already own, send us the models and we will map out the spacing and the fit with you.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013369655407,"sku":"FCD100-0806-02","price":1087.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/explore_scientific_fcd100_8006_01__25335.jpg?v=1766551596"},{"product_id":"explore-scientific-102mm-fcd100","title":"Explore Scientific ED102 FCD-100 Series 102mm f\/7 Air-Spaced Triplet Refractor Telescope","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific ED102 FCD-100 Series is a 102mm air-spaced triplet apochromatic refractor with a focal length of 714mm working at f\/7. The centre element is HOYA FCD100 extra-low-dispersion glass, and every air-to-glass surface carries Explore Scientific's EMD (Enhanced Multi-Layer Deposition) coating. For this aperture Explore Scientific publishes a limiting magnitude of 12.5 and a resolution of 1.14 arcsec.\u003c\/p\u003e\n\u003cp\u003eThe tube measures 30.5″ (774mm) with the dew shield extended and 23.75″ (603mm) with it retracted, over a 119mm outside diameter, at a published weight of 10.9 lb (4.94 kg). It carries a 2.5-inch focuser rated by Explore Scientific for imaging loads to 10 lb, and rides on a 45mm wide V-block dovetail of the Vixen pattern.\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\u003eWide-field imagers:\u003c\/strong\u003e 714mm at f\/7 puts the larger emission nebulae, the Andromeda core and the bigger open clusters inside a single APS-C frame, and the triplet holds star colour to the corners of the illuminated field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVisual observers who want colour-free high power:\u003c\/strong\u003e 1.14 arcsec of published resolution is enough for the Cassini division, the Jovian festoons and tight double pairs, with none of the violet halo an achromat shows on those targets.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTravelling observers:\u003c\/strong\u003e a 23.75-inch retracted tube at 10.9 lb fits luggage and small cases in a way a six-inch instrument does not.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers building a second imaging rig:\u003c\/strong\u003e this is a good match if you already own a mount rated comfortably above 11 lb and want a refractor that can front an imaging train today and guide a larger scope later.\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\u003e102mm air-spaced triplet:\u003c\/strong\u003e three elements in a single cell with air gaps rather than cement, built around a HOYA FCD100 extra-low-dispersion centre element.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e714mm focal length at f\/7:\u003c\/strong\u003e short enough for wide-field framing, long enough that eyepieces in the 5mm to 9mm range reach usable planetary powers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEMD enhanced multi-layer coatings\u003c\/strong\u003e on the air-to-glass surfaces, which is where transmission and stray-light control are won or lost in a three-element objective.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.5-inch focuser rated to 10 lb:\u003c\/strong\u003e Explore Scientific specifies the load capacity, which is the figure that matters once a camera, filter wheel and off-axis guider are hanging off the back.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRetracting dew shield:\u003c\/strong\u003e 30.5″ (774mm) extended, 23.75″ (603mm) retracted, so the transport length is nearly seven inches shorter than the working length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e119mm tube diameter\u003c\/strong\u003e with a 45mm wide V-block dovetail similar to the Vixen standard.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA triplet apochromat uses three elements to bring three wavelengths to a common focus, where a doublet manages two. The practical result is that the secondary spectrum — the residual colour error left over after the primary correction — drops to a level where it stops being visible on bright stars and stops bloating blue channels in a stacked image. The FCD100 glass in the centre element is a fluoro-crown type with very low dispersion, which is what makes that three-wavelength correction achievable in a cell only 102mm across.\u003c\/p\u003e\n\u003cp\u003eAir spacing rather than cementing gives the designer additional surfaces to work with and removes the cement layer as a thermal variable. It also means the objective cools as three separate pieces of glass, so a triplet takes longer to reach thermal equilibrium than a doublet of the same aperture. In practice that is twenty to forty minutes outside before the highest powers settle, which is worth knowing when planning a session.\u003c\/p\u003e\n\u003cp\u003eAt f\/7 the native field is not flat. Refractor objectives produce a curved focal surface, and across a large sensor that shows as stars stretching at the corners while the centre is sharp. A dedicated field flattener corrects it. Explore Scientific does not publish a corrected image circle or a backfocus figure for this tube, so no number is quoted here — we can work out the spacing with you against the camera and flattener you have in mind.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eWide-field deep-sky imaging of nebulae, large clusters and the brighter galaxies at 714mm.\u003c\/li\u003e\n\u003cli\u003eHigh-power visual work on the Moon, planets and double stars, where the 1.14 arcsec resolution figure governs.\u003c\/li\u003e\n\u003cli\u003eLunar and solar-system imaging with a focal extender to raise the effective focal length.\u003c\/li\u003e\n\u003cli\u003eTravel and dark-site trips where the 23.75-inch retracted length matters.\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\u003eMount:\u003c\/strong\u003e not part of the published package. At 10.9 lb bare, a mount rated at 25 lb or more gives the margin imaging wants once a camera and accessories are added.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDovetail:\u003c\/strong\u003e the 45mm wide V-block seats in Vixen-style saddles, including dual-fit saddles that take both Vixen and Losmandy plates.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyepieces:\u003c\/strong\u003e at 714mm, a 30mm eyepiece gives 24x, a 20mm gives 36x, a 9mm gives 79x and a 5mm gives 143x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocal extenders:\u003c\/strong\u003e a 2x extender takes the system to 1428mm at f\/14 for lunar and planetary imaging.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging train:\u003c\/strong\u003e the 2.5-inch focuser is specified to 10 lb, which accommodates most cooled CMOS cameras with a filter wheel and off-axis guider.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattener:\u003c\/strong\u003e needed for a flat field across an APS-C or larger sensor. Send us the camera and we will work through the spacing 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\u003eThis is an optical tube assembly.\u003c\/strong\u003e A mount, tripod and at least one eyepiece are separate items, and Explore Scientific does not publish an itemised box-contents list for this tube. We can check what is in the carton with our rep before you order, and put a package together if that is simpler.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific publishes two weight figures for this model.\u003c\/strong\u003e The current spec sheet for item FCD100-10207-02 lists 10.9 lb (4.94 kg); an earlier sheet for the aluminium FCD100-10207-01 listed 12 lb (5.4 kg). Both are shown here as published rather than averaged.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA triplet needs cooling time.\u003c\/strong\u003e Three separate elements reach ambient temperature more slowly than two, so the sharpest high-power views arrive some time after the tube goes outside rather than immediately.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo corrected image circle or backfocus figure is published\u003c\/strong\u003e for this tube, so those rows are absent from the specifications rather than estimated. If you are planning an imaging train, tell us the camera and flattener and we will map the spacing out 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\u003eThe optics need nothing — a refractor holds its collimation, so there is no alignment step before observing. The work is mounting it: 10.9 lb onto a levelled saddle, dovetail clamped, dew shield pulled out, and then a cooling period before the highest powers look their best.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat mount does it want?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eSomething rated well above 10.9 lb once a diagonal, finder and eyepiece or an imaging train are added. For visual work a 20 lb mount is comfortable; for imaging, 25 lb or more gives the settling margin that guiding depends on. Tell us what you have and we will give you a straight answer on the fit.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does FCD100 glass actually do?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt is a low-dispersion fluoro-crown glass that spreads wavelengths less than ordinary optical glass. Used as the centre element of a triplet, it allows three wavelengths to be brought to a common focus, which is what removes the violet halo an achromatic doublet shows on Venus, Sirius and the lunar limb.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it show colour fringing?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAn apochromatic triplet is designed to bring that below the visible threshold. On the very brightest targets at very high power a trace of residual colour is inherent to any refracting design, but it is a different order of magnitude from what a two-element achromat produces.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 102mm f\/7 air-spaced triplet on HOYA FCD100 glass, 714mm focal length, 10.9 lb, with a 2.5-inch focuser rated to 10 lb and a Vixen-pattern dovetail — a four-inch apochromat short enough to travel and capable enough to image with. If you are matching it to a mount or an existing camera, send us the details and we will work out the fit with you before you order.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Explore Scientific Field Flattener f\/5 to f\/7","offer_id":44013369720943,"sku":"FCD100-10207-02","price":1835.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/explore_scientific_fcd100_10207_01_102mm__86741.jpg?v=1766551603"},{"product_id":"102mm-fcd100-air-spaced-triplet-ed-apo-in-carbon-fiber","title":"Explore Scientific FCD-100 Series 102mm Carbon Fiber Air-Spaced Triplet ED Apo Refractor","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific FCD-100 Series 102mm carbon fiber apochromat is a four-inch refractor built around an air-spaced triplet objective made with FCD-100 extra-low-dispersion glass, carried in a carbon fiber optical tube. It is catalogued as item FCD100-10207-CF-01 — the carbon fiber version of the 102mm FCD-100 apochromat, distinct from the aluminium-tube 102mm which carries its own separate item number.\u003c\/p\u003e\n\u003cp\u003eExplore Scientific does not currently publish a specification table for this carbon fiber configuration. Focal length, focal ratio, tube length, focuser travel, dovetail pattern, backfocus and weight are therefore absent from the specifications below rather than estimated. The figures belonging to the aluminium-tube 102mm are not carried across to this listing, because that is a different model and its numbers are not ours to lend. What the model designation itself establishes is the part that governs the optics: 102mm of clear aperture, three elements in an air-spaced triplet, FCD-100 ED glass, and a carbon fiber tube.\u003c\/p\u003e\n\u003cp\u003eAperture on its own settles a good deal. A 102mm objective gathers roughly 212 times the light of a fully dark-adapted 7mm eye pupil, and Dawes' criterion for a 102mm aperture works out to about 1.14 arcseconds — the separation at which a tight double star begins to resolve into two points. Both are calculations from the aperture figure rather than published specifications.\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 who want colour-free high power in a four-inch tube:\u003c\/strong\u003e a triplet apochromat is designed to bring three wavelengths to a common focus, which is what removes the violet halo that a two-element achromat leaves around Venus, Jupiter and the lunar limb.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeep-sky imagers:\u003c\/strong\u003e the combination of a triplet objective and a carbon fiber tube targets the two things that spoil a long exposure — colour spread across the star field, and focus drifting as the night cools.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePeople who already own a capable equatorial or alt-az mount.\u003c\/strong\u003e This is a good match if you have a mount with capacity to spare and want a four-inch apochromat to put on it.\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\u003e102mm clear aperture:\u003c\/strong\u003e four inches of light grasp, with a theoretical resolution near 1.14 arcseconds by Dawes' criterion.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAir-spaced triplet objective:\u003c\/strong\u003e three elements with air gaps between them rather than cement, giving the designer six optical surfaces to shape instead of the four a cemented pair offers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFCD-100 extra-low-dispersion glass:\u003c\/strong\u003e an ED glass type chosen for its low dispersion, which is the property that lets a triplet close the secondary spectrum rather than merely reduce it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCarbon fiber optical tube:\u003c\/strong\u003e carbon composite has a far lower coefficient of thermal expansion than aluminium, so the distance between objective and focal plane changes less as the ambient temperature falls through the night.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePublished data is limited:\u003c\/strong\u003e the model designation is the whole of what Explore Scientific states publicly for this configuration, so the rest of the table reads \"Not published by vendor\" instead of carrying a borrowed figure.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eAn apochromatic triplet works on the same principle as an achromatic doublet, taken a step further. A doublet pairs a crown element with a flint element so that two wavelengths — typically in the red and the blue — land on the same focal plane, leaving a residual violet focus error known as the secondary spectrum. A triplet adds a third element, usually with an extra-low-dispersion glass such as FCD-100 in the middle of the stack, and brings a third wavelength onto that plane as well. The residual colour error drops by roughly an order of magnitude, which is why bright stars in an apochromat show as clean points rather than as points wearing a purple ring.\u003c\/p\u003e\n\u003cp\u003eAir-spacing the elements rather than cementing them serves two ends. It gives the optical designer additional free surfaces to shape and additional degrees of freedom in balancing spherical aberration against colour correction. It also removes the cement layer as a thermal variable: in a four-inch objective, a bonded interface between glasses of differing expansion rates is one more thing that has to settle as the lens cools toward ambient.\u003c\/p\u003e\n\u003cp\u003eThe carbon fiber tube is doing thermal work of its own. Every refractor has a fixed distance from the objective to the focal plane, and every tube material changes length as it cools. Aluminium moves enough over a twenty-degree evening drop to be visible in a critically focused image at high magnification or on a small imaging pixel scale. Carbon composite moves far less, so a focus position set at the start of an imaging run holds closer to true through the session. The same stiffness-to-weight advantage also keeps flexure between the objective cell and the focuser lower for a given tube mass. What the design cannot settle without a published focal length is the focal ratio, the field any eyepiece will deliver, or the illuminated image circle at the camera — and those we would rather leave blank than guess at.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power visual observing of the Moon, planets and double stars, where colour correction is the limiting factor rather than aperture.\u003c\/li\u003e\n\u003cli\u003eDeep-sky imaging, where a triplet objective keeps star colour tight across the frame.\u003c\/li\u003e\n\u003cli\u003eLong imaging sessions through a falling temperature, where a low-expansion tube reduces the number of refocus stops.\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\u003eMount:\u003c\/strong\u003e the tube weight is not published for this configuration, so a mount recommendation from us would be a guess. We can obtain the figure from Explore Scientific and match it against the mount you own before you order.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDovetail:\u003c\/strong\u003e the pattern supplied with the carbon fiber version is not stated on the vendor page. Vixen-style and Losmandy-style saddles are the two common standards, and we can tell you which one applies once we have it in writing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyepieces and magnification:\u003c\/strong\u003e magnification is telescope focal length divided by eyepiece focal length, so without a published focal length for this tube we are not going to quote example magnifications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flatteners and reducers:\u003c\/strong\u003e a triplet apochromat corrects colour, not field curvature, so imaging across an APS-C or full-frame sensor generally calls for a flattener matched to the focal length. That match depends on figures the vendor has not published here, so we would sort the spacing out with you rather than sell a flattener blind.\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\u003eExplore Scientific publishes no specification table for the carbon fiber 102mm.\u003c\/strong\u003e Focal length, focal ratio, focuser type, tube length, dovetail and weight are all absent from their page for this item number. Rather than lift them from the aluminium-tube model, we have left those rows blank — and if any one of them is the deciding factor for you, we will put the question to our Explore Scientific rep and come back with an answer in writing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe in-the-box list is also unpublished.\u003c\/strong\u003e Whether a diagonal, finder or rings ship with this configuration is not stated, so we will confirm exactly what is in the carton with the distributor before anything leaves here.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCarbon fiber reduces focus drift rather than eliminating it.\u003c\/strong\u003e Long imaging runs still benefit from periodic refocusing or an autofocus routine, and we stock motorised focusers that handle that automatically.\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. A refractor holds its collimation from the factory, so there is nothing to align before first light — the tube goes into the saddle, the diagonal and eyepiece go into the focuser, and it is ready. The only real work is balancing the mount once the tube is on it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will it give?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThat depends on the focal length, and Explore Scientific has not published one for this configuration. We would rather ask them than quote a number we cannot stand behind, so if the answer matters to your eyepiece plan, ask us and we will get it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does FCD-100 glass actually do?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt is an extra-low-dispersion optical glass. Dispersion is the tendency of glass to bend different wavelengths by different amounts, which is the root cause of chromatic aberration. A low-dispersion element in the middle of a triplet lets the design bring red, green and blue essentially to the same focus instead of leaving violet behind.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhy a carbon fiber tube instead of aluminium?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThermal stability and stiffness for the mass. Carbon composite changes length far less than aluminium as the night cools, which keeps focus closer to where you set it, and it is rigid without being heavy.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I image with it?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt is built for it — a triplet apochromat on a low-expansion tube is a deep-sky imaging configuration. The accessories that go with it (flattener, spacers, filter drawer) depend on the focal length and backfocus, which is where we can help once those figures are in hand.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 102mm air-spaced triplet apochromat using FCD-100 ED glass in a carbon fiber tube — four inches of three-colour correction on a low-expansion tube, with a specification table Explore Scientific has not yet published for this particular item number. If there is a figure you need before committing, send us the question and we will get it from Explore Scientific and pass on exactly what they tell us.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013376045167,"sku":"FCD100-10207-CF-01","price":2632.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100_102ED_CF_Burst__17456.jpg?v=1766552108"},{"product_id":"127mm-fcd100-air-spaced-triplet-ed-apo-in-carbon-fiber","title":"Explore Scientific FCD100 Series ED127 127mm f\/7.5 Carbon Fiber Air-Spaced Triplet APO Refractor Telescope","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific ED127 FCD100 Series is a 127mm air-spaced triplet apochromatic refractor with a focal length of 952mm at f\/7.5, built into a carbon fiber optical tube. The centre element of the triplet is HOYA FCD100 extra-low-dispersion glass, and the front and rear elements are air-spaced against it rather than cemented. Explore Scientific publishes a limiting magnitude of 13 and a resolution figure of .9 arcsec for this aperture.\u003c\/p\u003e\n\u003cp\u003eIt is supplied as an optical tube assembly with a 2.5″ HEX focuser rated to carry 10 lb of imaging equipment, and a Vixen-pattern dovetail. The tube measures 41.75″ (1060mm) with the dew shield extended and 33.25″ (849mm) with it retracted, 145mm across, and weighs 14 lb (6.4 kg). No mount and no eyepieces are included.\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\u003eDeep-sky imagers:\u003c\/strong\u003e 952mm at f\/7.5 is a long-enough focal length for galaxies and small nebulae without becoming an autoguiding problem, and the 2.5″ HEX focuser is specified to hold 10 lb of camera, filter wheel and rotator without sagging.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVisual observers who want colour-free high power:\u003c\/strong\u003e an air-spaced triplet using FCD100 glass is built to bring three wavelengths to a common focus, which is what removes the violet halo an achromat shows on Venus, Jupiter and the lunar limb.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers who travel to dark sites:\u003c\/strong\u003e this is a good match if you want five inches of apochromatic aperture that one person can carry to the car in a single trip. The carbon fiber tube is the reason the published weight is 14 lb rather than what a comparable aluminium tube would read.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOwners of mid-capacity equatorial mounts:\u003c\/strong\u003e this is a good match if your mount is rated comfortably above the loaded weight of a 14 lb tube plus rings, diagonal, finder and camera train.\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\u003e127mm air-spaced triplet:\u003c\/strong\u003e three elements with air gaps between them, rather than a cemented pair, giving the designer additional surfaces to work with and removing cement as a thermal variable in a five-inch lens.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHOYA FCD100 ED glass:\u003c\/strong\u003e a high-grade extra-low-dispersion type used for the centre element, chosen for how tightly it brings the red, green and blue focal points together.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e952mm focal length at f\/7.5:\u003c\/strong\u003e a moderate focal ratio that keeps the image scale useful for galaxies and planetary detail while remaining tractable for imaging exposures.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.5″ HEX focuser:\u003c\/strong\u003e rated by Explore Scientific to support up to 10 lb of imaging equipment, so a camera, filter wheel and off-axis guider can ride on it together.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCarbon fiber optical tube:\u003c\/strong\u003e stiffness per unit weight is the point — it is what allows a 127mm triplet to be published at 14 lb (6.4 kg).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRetracting dew shield:\u003c\/strong\u003e 41.75″ (1060mm) extended, 33.25″ (849mm) retracted, which is the figure that matters for a case or a back seat.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVixen-pattern dovetail\u003c\/strong\u003e for mounting, on a tube 145mm in outside diameter.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA doublet achromat brings two wavelengths to a common focus and leaves a residual violet fringe on the brightest targets. A triplet apochromat adds a third element so that three widely separated wavelengths land together, and the residual colour error drops to the point where it stops being visible at normal magnifications. The glass type in the centre element governs how well that works: extra-low-dispersion glass bends the different colours by more nearly the same amount, so less correction has to be forced by the surface curvatures. FCD100 is one of the higher-performing ED types HOYA produces, and it is what this tube is named for.\u003c\/p\u003e\n\u003cp\u003eAir-spacing the elements, rather than cementing them, matters more as lenses get larger. A cemented joint in a 127mm lens is a thick layer of adhesive that expands and contracts with temperature at a different rate to the glass around it. Separating the elements removes that layer, adds two more optical surfaces the designer can shape, and lets the lens reach thermal equilibrium more predictably on a cooling night.\u003c\/p\u003e\n\u003cp\u003eExplore Scientific does not publish a corrected image circle or a backfocus distance for this tube, so those rows are absent from the specifications rather than estimated. If you are planning an imaging train around a specific camera and flattener, send us the parts you have in mind and we will work the spacing out with you before you order.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eDeep-sky astrophotography of galaxies, globular clusters and small to medium emission nebulae at 952mm.\u003c\/li\u003e\n\u003cli\u003eHigh-power visual observing of the Moon, planets and planetary detail where colour correction is the limiting factor.\u003c\/li\u003e\n\u003cli\u003eDouble-star work near the published .9 arcsec resolution.\u003c\/li\u003e\n\u003cli\u003ePortable dark-site sessions where the 14 lb tube weight and 33.25″ retracted length are what make the trip practical.\u003c\/li\u003e\n\u003cli\u003eLunar and planetary imaging with a focal extender in the train.\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\u003eMount:\u003c\/strong\u003e not included. The published tube weight of 14 lb is before rings, dovetail hardware, diagonal, finder and camera. For imaging, a mount rated at roughly twice the loaded tube weight is the usual working rule; for visual use the margin can be smaller.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDovetail:\u003c\/strong\u003e Vixen pattern, which fits Vixen saddles and dual-fit saddles that take both Vixen and Losmandy plates.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyepieces:\u003c\/strong\u003e not included. At 952mm, a 30mm eyepiece gives 32x, a 20mm gives 48x, a 9mm gives 106x and a 5mm gives 190x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDiagonal:\u003c\/strong\u003e the 2.5″ focuser takes 2-inch diagonals with the appropriate adapter. We stock dielectric 2-inch diagonals if one is not already in your case.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging train:\u003c\/strong\u003e a field flattener is the normal companion for deep-sky work with any refractor. Since no corrected image circle is published, we will confirm the flattener match against your camera rather than quote a figure.\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\u003eThis is an optical tube assembly, not a complete telescope.\u003c\/strong\u003e A mount, a tripod and at least one eyepiece are needed alongside it. We can quote the whole package together if that is simpler — just tell us what you already own.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific has published two different outer-diameter figures for this tube\u003c\/strong\u003e — 130mm on the spec sheet supplied with the product and 145mm on the current product page. If the exact figure decides whether a set of rings or a case will fit, ask us and we will confirm it with our Explore Scientific rep before you commit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe 41.75″ length is with the dew shield extended.\u003c\/strong\u003e Retracted it is 33.25″, which is the number to measure a case or a vehicle against.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo corrected image circle or backfocus figure is published\u003c\/strong\u003e for this tube, so those rows are left out below rather than filled with an estimate. Send us your camera and intended flattener and we will work out the spacing with you.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe 10 lb focuser rating is a real ceiling.\u003c\/strong\u003e A camera, filter wheel, off-axis guider and rotator add up quickly, and staying inside that figure is what keeps the focuser drawtube square to the optical axis. We can total up a proposed train for you if you are close to the limit.\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\u003eThe telescope itself is simple — a refractor holds its collimation, so once the tube is in the rings and on the mount it is ready. The work is in the mount and the balance: at 14 lb plus accessories it is a comfortable one-person lift, and it goes on easiest with the mount already levelled and the counterweights roughly set.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat mount will carry it?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eFor visual use, a mount rated well above the 14 lb tube weight once rings, diagonal, finder and eyepiece are added. For imaging, more headroom again, because tracking accuracy degrades long before a mount reaches its stated capacity. Tell us which mount you own and we will give you a straight answer on whether it is enough.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill I see colour fringing?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eAn air-spaced triplet using FCD100 ED glass is designed specifically to remove it. On Venus, Sirius and the lunar limb at high power an apochromat of this class shows a clean, neutral image where a two-element achromat would show violet.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I image with it?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes — that is a large part of what the 2.5″ HEX focuser and its 10 lb capacity are for. A field flattener is the usual addition for deep-sky work, and an equatorial mount with guiding is the other half of the system.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 127mm f\/7.5 air-spaced triplet apochromat with HOYA FCD100 ED glass, a 2.5″ HEX focuser rated to 10 lb, and a carbon fiber tube that keeps the whole assembly at 14 lb with a Vixen dovetail — five inches of apochromatic aperture on a mount that does not have to be enormous. If you are matching it to a mount or building an imaging train around it, send us the parts list and we will confirm the fit with you first.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":44013377781871,"sku":"FCD100-127075-CF-01","price":3880.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100_127ED_CF__51061.jpg?v=1766552312"},{"product_id":"explore-scientific-ed80-fcd100-triplet-refractor-0-8x-focal-reducer","title":"Explore Scientific ED80-FCD100 80mm f\/6 Air-Spaced Triplet Refractor with 0.8x Focal Reducer","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThe Explore Scientific ED80-FCD100 is an 80 mm f\/6 air-spaced apochromatic triplet refractor using HOYA FCD-100 extra-low-dispersion glass, the higher grade in Explore Scientific's ED line. Focal length is 480 mm and the tube assembly weighs 7.5 lb. This configuration includes the Explore Scientific 0.8x focal reducer, which brings the working system to f\/4.8 for wide-field imaging.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis suits an imager who wants the strongest colour correction available in a compact 80 mm tube, and an observer who values a clean, halo-free view on the Moon, planets, and bright double stars. Compared with the Essential Series version of the same optical layout, the FCD-100 glass reduces residual colour further; it is the choice when the telescope will be doing serious long-exposure work rather than occasional imaging.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eHOYA FCD-100 ED glass in an air-spaced triplet objective — Explore Scientific's premium ED substrate\u003c\/li\u003e\n\u003cli\u003eIncluded 0.8x focal reducer yields an f\/4.8 imaging system\u003c\/li\u003e\n\u003cli\u003e2.5-inch hexagonal rack-and-pinion focuser rated for 10 lb of imaging equipment\u003c\/li\u003e\n\u003cli\u003e99% reflective 2-inch dielectric diagonal included for visual use\u003c\/li\u003e\n\u003cli\u003eTwo focuser extension tubes to reach focus with varied eyepiece and camera trains\u003c\/li\u003e\n\u003cli\u003eRetractable dew shield and Hybrid 2N1 finder base fitted to the tube\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eOptical and Mechanical Design\u003c\/h2\u003e\u003cp\u003eThree air-spaced elements, one of them FCD-100 ED glass, hold chromatic aberration low enough that bright stars record as points rather than as blue-fringed discs. Resolution is 1.45 arcseconds and limiting magnitude is 12. The tube is 18.5 inches long with the dew shield out and 15 inches retracted, 85 mm in diameter, on a Vixen-style dovetail. At 7.5 lb it is heavier than the Essential Series tube, which is worth accounting for when sizing a mount.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eLong-exposure deep-sky imaging of nebulae, galaxies, and clusters at f\/4.8\u003c\/li\u003e\n\u003cli\u003eHigh-contrast visual observing of the Moon, planets, and double stars\u003c\/li\u003e\n\u003cli\u003eNarrowband imaging, where the flat, well-corrected field pays off across the frame\u003c\/li\u003e\n\u003cli\u003ePortable dark-site setups that still need apochromatic performance\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe Vixen-style dovetail fits standard Vixen saddles, including the Explore Scientific iEXOS-100-2 and EXOS-2GT. The reducer presents a 42 mm T2 thread on the camera side, so add the T2 camera ring that matches your body; its barrel also takes standard 2-inch filters. The Hybrid 2N1 base accepts an Explore Scientific finder scope, sold separately.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eThis is an optical tube with a reducer — mount, tripod, eyepieces, and finder scope are separate purchases. Explore Scientific publishes a 7.5 lb tube weight; the checkout shipping weight is rounded up to the next whole pound and does not alter the specification. Explore Scientific does not publish a separate weight for the reducer, so the shipping figure covers the tube and packaging.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e No. The dovetail seats in a Vixen saddle, the dew shield pulls out by hand, and the reducer threads on with the supplied adapter. Nothing requires collimation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is this different from the ED80 Essential Series?\u003c\/strong\u003e Same 80 mm f\/6 triplet geometry; this one uses FCD-100 glass instead of FCD-1 and weighs 7.5 lb rather than 5.95 lb. The FCD-100 gives a further reduction in residual colour.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I still get a full-aperture visual setup?\u003c\/strong\u003e Yes. Fit the included 2-inch diagonal and an eyepiece; remove it and thread on the reducer when you want to image.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat size mount should I plan for?\u003c\/strong\u003e Something rated well above 7.5 lb once a camera or diagonal and eyepiece are added. The iEXOS-100-2 handles it for imaging.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eExplore Scientific's best 80 mm ED glass, with the 0.8x reducer already included so the telescope arrives ready to image at f\/4.8. A compact apochromat that does not compromise on colour correction. Talk to our team in Bolton if you would like help pairing it with a mount.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53955240951919,"sku":"ES-FCD100-0806-FR0.8x","price":1149.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100_80mm_2_Burst_004bc693-2c8f-4f74-a888-29f541afe1bf.jpg?v=1785950965"},{"product_id":"explore-scientific-ed80-fcd100-triplet-refractor-field-flattener","title":"Explore Scientific ED80-FCD100 80mm f\/6 Air-Spaced Triplet Refractor with Field Flattener","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThe Explore Scientific ED80-FCD100 is an 80 mm f\/6 air-spaced apochromatic triplet refractor built with HOYA FCD-100 extra-low-dispersion glass. Focal length is 480 mm and the tube assembly weighs 7.5 lb. This configuration pairs the telescope with the Explore Scientific Field Flattener for f\/5 to f\/7 refractors, which corrects the field curvature that otherwise smears stars toward the corners of a long exposure.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis is aimed at the imager who wants flat, round stars across the whole frame at the telescope's native f\/6 rather than a faster reduced focal ratio. Where the 0.8x reducer version trades focal length for speed, this configuration keeps all 480 mm and spends the correction on field flatness — the better choice for larger camera sensors and for anyone who prefers native framing.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eHOYA FCD-100 ED glass in an air-spaced triplet objective\u003c\/li\u003e\n\u003cli\u003eIncluded field flattener matched to f\/5 through f\/7 refractors for edge-to-edge star sharpness\u003c\/li\u003e\n\u003cli\u003e2.5-inch hexagonal rack-and-pinion focuser rated for 10 lb of imaging equipment\u003c\/li\u003e\n\u003cli\u003e99% reflective 2-inch dielectric diagonal included for visual observing\u003c\/li\u003e\n\u003cli\u003eTwo focuser extension tubes for reaching focus across different trains\u003c\/li\u003e\n\u003cli\u003eRetractable dew shield and Vixen-style dovetail\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eOptical and Mechanical Design\u003c\/h2\u003e\u003cp\u003eField curvature grows worse as focal ratio gets faster and as sensors get larger; uncorrected, stars near the frame edge stretch radially into small comet shapes. The field flattener sits in the imaging train ahead of the camera and returns the focal plane to flat, so stars at the corners focus at the same point as those at centre. Resolution is 1.45 arcseconds, limiting magnitude 12. The tube runs 18.5 inches with the dew shield extended, 15 inches retracted, 85 mm in diameter.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDeep-sky imaging at native f\/6 with round stars to the frame corners\u003c\/li\u003e\n\u003cli\u003eImaging with APS-C and larger sensors, where field curvature shows most\u003c\/li\u003e\n\u003cli\u003eVisual observing of the Moon, planets, and double stars with the included diagonal\u003c\/li\u003e\n\u003cli\u003eMosaic and multi-panel projects that need consistent star shapes across panels\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe flattener is specified for refractors between f\/5 and f\/7, which covers this telescope at f\/6. The Vixen-style dovetail fits standard Vixen saddles including the iEXOS-100-2 and EXOS-2GT. Reaching correct spacing between flattener and sensor is what determines corner performance, so plan on the T-thread adapters and spacers that match your camera; our team can work out the stack for your body. A finder scope is not included.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eMount, tripod, eyepieces, camera adapters, and finder scope are separate purchases. Explore Scientific does not publish a \"what's in the box\" list for this configuration, so the included-items detail above reflects the tube and flattener specifications they do publish; contact us if you need the packing list confirmed before ordering. Published tube weight is 7.5 lb, and the shipping weight at checkout is rounded up to the next whole pound.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e The telescope itself is simple — dovetail into the saddle, dew shield out by hand. The one job that rewards care is setting flattener-to-sensor spacing, and we can specify the adapters for your camera so it is right the first time.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eFlattener or 0.8x reducer — which should I choose?\u003c\/strong\u003e The flattener keeps 480 mm at f\/6 and flattens the field. The reducer shortens to 384 mm at f\/4.8 for shorter exposures and wider framing. Larger sensors and native framing favour the flattener.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I observe visually with it?\u003c\/strong\u003e Yes. Fit the included 2-inch diagonal and an eyepiece.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it work on a small mount?\u003c\/strong\u003e It needs a mount rated comfortably past 7.5 lb plus camera and accessories. The iEXOS-100-2 is a common pairing.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eAn 80 mm FCD-100 apochromat supplied with the matching field flattener, for imagers who want native focal length and clean stars in the corners. Get in touch and we will spec the spacing for your camera.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53955258548335,"sku":"ES-FCD100-0806-FF","price":1149.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100-0806-02-FF.jpg?v=1785951047"},{"product_id":"es-ed80-fcd100-refractor-0-8x-reducer-iexos-100-2-package","title":"Explore Scientific ED80-FCD100 Triplet Refractor with 0.8x Focal Reducer and iEXOS-100-2 PMC-Eight GoTo Mount","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThis package combines the Explore Scientific ED80-FCD100 80 mm f\/6 air-spaced triplet refractor with the 0.8x focal reducer and the iEXOS-100-2 PMC-Eight equatorial tracker system. The FCD-100 version uses Explore Scientific's premium HOYA ED substrate, and with the reducer fitted the system works at f\/4.8 on a computerised GoTo mount with WiFi and Bluetooth, tripod and counterweights included.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis is for the imager who wants the best colour correction available in a compact 80 mm tube and a tracking mount to go with it, in one purchase. Where the Essential Series package is the value option, this one spends the difference on glass — worth it if the rig will be doing regular long-exposure work rather than occasional imaging.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eED80-FCD100 80 mm f\/6 air-spaced triplet, HOYA FCD-100 ED glass, 480 mm focal length\u003c\/li\u003e\n\u003cli\u003e0.8x focal reducer producing an f\/4.8 imaging system\u003c\/li\u003e\n\u003cli\u003eiEXOS-100-2 PMC-Eight GoTo equatorial tracker with WiFi and Bluetooth\u003c\/li\u003e\n\u003cli\u003eEight-core PMC-Eight motion control with tasks distributed across CPUs for smoother tracking\u003c\/li\u003e\n\u003cli\u003eFree ExploreStars app for Windows, Android, Amazon Fire, and Apple tablets, plus an ASCOM driver\u003c\/li\u003e\n\u003cli\u003e2.5-inch hexagonal focuser rated to 10 lb, 99% reflective 2-inch diagonal, two extension tubes, counterweights\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eOptical and Mechanical Design\u003c\/h2\u003e\u003cp\u003eFCD-100 glass in an air-spaced triplet holds residual colour lower than the FCD-1 equivalent, which shows on bright stars and at high power on the Moon and planets. Resolution is 1.45 arcseconds, limiting magnitude 12, and the tube weighs 7.5 lb at 85 mm diameter. The German equatorial mount head weighs 9.45 lb with a 5.35 lb tripod and 1 kg counterweights, rated at approximately 9 lb of equipment alone, 15 lb photographic and 19 lb visual with counterweights counted. The tripod goes from 25.5 inches collapsed to 45 inches extended with the head fitted.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eTracked deep-sky imaging at f\/4.8 on nebulae, galaxies, and clusters\u003c\/li\u003e\n\u003cli\u003eNarrowband work, where the flat well-corrected field pays across the frame\u003c\/li\u003e\n\u003cli\u003eGoTo-assisted visual observing with the included 2-inch diagonal\u003c\/li\u003e\n\u003cli\u003ePortable dark-site setups that still need apochromatic performance\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe Vixen-style dovetail drops into the mount's saddle as supplied. The reducer carries a 42 mm T2 thread on the camera side, so add a T2 ring for your body; the barrel takes standard 2-inch filters. The mount is driven over WiFi, Bluetooth, or wired serial and works with any ASCOM-compatible software; a tablet or computer is not included. The Hybrid 2N1 finder base is fitted and a finder scope is separate.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eEyepieces are not included, and a tablet or laptop is needed for GoTo. Power comes from a battery pack or a 12 V DC supply, which we stock. On weight: Explore Scientific publishes 7.5 lb for the tube, 9.45 lb for the mount head, 5.35 lb for the tripod and 1 kg per counterweight, and no figure for the reducer. The checkout shipping weight is the sum of those published figures rounded up to the next whole pound; it does not replace the specifications above.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e Assembly is quick. Polar alignment and the app's star alignment take a first evening to learn, and Explore Scientific publishes guides for both. We are happy to talk you through your first night.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eFCD-100 or the Essential Series version?\u003c\/strong\u003e Same 80 mm f\/6 triplet geometry. FCD-100 glass reduces residual colour further; the tube is 7.5 lb against 5.95 lb.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need a computer?\u003c\/strong\u003e For GoTo, yes — a tablet running ExploreStars, or a laptop with ASCOM software.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it visually?\u003c\/strong\u003e Yes, with the included 2-inch diagonal and an eyepiece of your choice.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eExplore Scientific's best 80 mm ED glass, the matching reducer, and a GoTo mount in a single package that images at f\/4.8 out of the box. Add a camera and an eyepiece and it is complete — our team can spec both.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53955284336751,"sku":"ES-FCD100-0806-FR0.8x-IEXOS100","price":2355.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100-0806-FR-iEXOS_1.jpg?v=1785951168"},{"product_id":"es-ed80-fcd100-refractor-field-flattener-iexos-100-2-package","title":"Explore Scientific ED80-FCD100 Triplet Refractor with Field Flattener and iEXOS-100-2 PMC-Eight GoTo Mount","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThis package pairs the Explore Scientific ED80-FCD100 80 mm f\/6 air-spaced triplet refractor with the field flattener for f\/5 to f\/7 refractors and the iEXOS-100-2 PMC-Eight equatorial tracker system. It is a complete imaging setup that works at the telescope's native 480 mm focal length, with the corrector spent on field flatness rather than speed, on a computerised GoTo mount with tripod and counterweights included.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis suits an imager using an APS-C or larger sensor, where field curvature shows most plainly, and anyone who prefers native framing to the wider, faster field a reducer gives. It is also a straightforward first complete rig: telescope, corrector, and mount are matched at purchase, so the dovetail, saddle, and payload rating all line up.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eED80-FCD100 80 mm f\/6 air-spaced triplet, HOYA FCD-100 ED glass, 480 mm focal length\u003c\/li\u003e\n\u003cli\u003eField flattener matched to f\/5 through f\/7 refractors for edge-to-edge star sharpness\u003c\/li\u003e\n\u003cli\u003eiEXOS-100-2 PMC-Eight GoTo equatorial tracker with WiFi and Bluetooth\u003c\/li\u003e\n\u003cli\u003eEight-core PMC-Eight motion control, with CPUs assigned to separate tasks for smoother tracking\u003c\/li\u003e\n\u003cli\u003eFree ExploreStars app for Windows, Android, Amazon Fire, and Apple tablets, plus an ASCOM driver\u003c\/li\u003e\n\u003cli\u003e2.5-inch hexagonal focuser rated to 10 lb, 99% reflective 2-inch diagonal, two extension tubes, counterweights\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eOptical and Mechanical Design\u003c\/h2\u003e\u003cp\u003eField curvature makes stars near the frame edge stretch radially into small comet shapes; the flattener sits ahead of the camera and returns the focal plane to flat so corner stars come to focus with the centre. The objective gives 1.45 arcsecond resolution and a limiting magnitude of 12, in a 7.5 lb tube of 85 mm diameter. The mount head weighs 9.45 lb on a 5.35 lb tripod with 1 kg counterweights, rated at approximately 9 lb of equipment alone, 15 lb photographic and 19 lb visual with counterweights. Tripod height runs 25.5 inches collapsed to 45 inches extended with the head fitted.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eTracked deep-sky imaging at native f\/6 with round stars into the corners\u003c\/li\u003e\n\u003cli\u003eImaging with APS-C and larger sensors\u003c\/li\u003e\n\u003cli\u003eMosaic projects needing consistent star shapes panel to panel\u003c\/li\u003e\n\u003cli\u003eGoTo-assisted visual observing with the included 2-inch diagonal\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe flattener is specified for f\/5 to f\/7 refractors, which covers this telescope at f\/6. Corner performance depends on getting the spacing between flattener and sensor right, so plan on the T-thread adapters and spacers that match your camera — we can work the stack out for your body. The Vixen-style dovetail seats in the mount's saddle as supplied. A tablet or computer for GoTo is not included, and a finder scope is separate.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eEyepieces, camera adapters, and a tablet or laptop are separate. Power for the PMC-Eight comes from a battery pack or a 12 V DC supply, which we stock. Explore Scientific publishes no packing list for this configuration, so the included items above reflect the tube, flattener, and mount specifications they do publish — ask us if you need it confirmed before ordering. Published weights are 7.5 lb tube, 9.45 lb mount head, 5.35 lb tripod, 1 kg per counterweight; the checkout shipping weight is the sum of those rounded up to the next whole pound.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e Assembly is quick. Two things reward care: polar alignment, for which Explore Scientific publishes a guide, and flattener-to-sensor spacing, which we can specify for your camera so it is right first time.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eFlattener or 0.8x reducer?\u003c\/strong\u003e The flattener keeps 480 mm at f\/6 and flattens the field; the reducer shortens to 384 mm at f\/4.8 for wider, faster framing. Larger sensors favour the flattener.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need a computer?\u003c\/strong\u003e For GoTo, yes — a tablet running ExploreStars, or a laptop with ASCOM software.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I observe visually?\u003c\/strong\u003e Yes, using the included 2-inch diagonal and an eyepiece.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eA premium 80 mm apochromat, its matching flattener, and a GoTo mount together in one package, set up for flat-field imaging at native focal length. Get in touch and we will spec the camera spacing for you.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53955301933167,"sku":"ES-FCD100-0806-FF-IEXOS100","price":2355.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FCD100-0806-FF-IEXOS100.jpg?v=1785951221"},{"product_id":"es-ed102-fcd100-carbon-fiber-refractor-iexos-100-2-package","title":"Explore Scientific ED102-FCD100 102mm f\/7 Carbon Fiber Air-Spaced Triplet Refractor with iEXOS-100-2 PMC-Eight GoTo Mount","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThis package pairs the Explore Scientific ED102-FCD100 with the iEXOS-100-2 PMC-Eight equatorial tracker system. The telescope is a 102 mm f\/7 air-spaced apochromatic triplet using HOYA FCD-100 extra-low-dispersion glass in a carbon fibre tube, at 714 mm focal length and 9.5 lb. It arrives with a computerised GoTo mount, tripod, and counterweights.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis is the step up in aperture from the 80 mm triplets while staying genuinely portable — the carbon fibre tube is what makes that possible. It suits an imager who wants more resolution and a longer native focal length for galaxies and planetary nebulae, and a visual observer who wants a 4-inch apochromat that still travels easily.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e102 mm f\/7 air-spaced triplet with HOYA FCD-100 ED glass, 714 mm focal length\u003c\/li\u003e\n\u003cli\u003eCarbon fibre tube, holding weight to 9.5 lb and reducing focus shift as temperature drops\u003c\/li\u003e\n\u003cli\u003e45 mm wide Vixen-style dovetail plate with cone-angle adjustments\u003c\/li\u003e\n\u003cli\u003eiEXOS-100-2 PMC-Eight GoTo equatorial tracker with WiFi and Bluetooth\u003c\/li\u003e\n\u003cli\u003eEight-core PMC-Eight motion control, tasks distributed across CPUs for smoother tracking\u003c\/li\u003e\n\u003cli\u003eHeavy-duty 2.5-inch HEX focuser rated to carry 10 lb of imaging equipment\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eOptical and Mechanical Design\u003c\/h2\u003e\u003cp\u003eA true air-spaced triplet with an FCD-100 element delivers diffraction-limited performance with residual colour low enough that bright stars record without a violet halo across the field. Carbon fibre matters for two reasons: it cuts weight, which is what lets a 4-inch triplet sit on a compact mount, and it expands far less than aluminium as the night cools, so focus holds through a long imaging session. The mount head weighs 9.45 lb on a 5.35 lb tripod with 1 kg counterweights, rated at approximately 9 lb of equipment alone and 15 lb photographic once counterweights are counted. Tripod height runs 25.5 inches collapsed to 45 inches extended with the head fitted.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDeep-sky imaging of galaxies, planetary nebulae, and smaller clusters at 714 mm\u003c\/li\u003e\n\u003cli\u003eHigh-resolution lunar and planetary observing and imaging\u003c\/li\u003e\n\u003cli\u003eDouble star work, where the extra aperture separates closer pairs\u003c\/li\u003e\n\u003cli\u003eTravel and dark-site trips needing 4-inch apochromatic performance in a light package\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThe 45 mm dovetail plate is Vixen-style and seats in the mount's saddle as supplied; the cone-angle adjustments let you square the tube to the mount for accurate GoTo pointing. At f\/7 the telescope falls inside the range of the Explore Scientific field flattener for f\/5 to f\/7 refractors, which we stock separately, and a 0.7x reducer-corrector is also available for it. The mount runs over WiFi, Bluetooth, or wired serial with the ExploreStars app or any ASCOM-compatible software; a tablet or computer is not included.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eThe 9.5 lb tube sits close to the mount's 9 lb equipment-only rating, so this pairing is best used with the counterweights fitted as supplied and a modest camera rather than a heavy imaging train — talk to us if you plan to add a filter wheel and off-axis guider. Explore Scientific publishes no packing list for this configuration, so the items above reflect the tube and mount specifications they do publish. Eyepieces, diagonal, camera adapters, and a tablet are separate. Published weights are 9.5 lb tube, 9.45 lb mount head, 5.35 lb tripod, 1 kg per counterweight; the checkout shipping weight is the sum rounded up to the next whole pound.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e Mechanically no — the dovetail drops in and the counterweights slide on. Polar alignment and star alignment take a first evening to learn, and Explore Scientific publishes guides for both.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the mount big enough for this telescope?\u003c\/strong\u003e It is within rating with the supplied counterweights, and fine for a camera or eyepiece. If you intend to hang a full imaging train off the back, a heavier mount such as the EXOS-2GT is the safer pairing, and we can quote that combination.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy carbon fibre?\u003c\/strong\u003e Lower weight and far less focus drift as the temperature falls, which matters over a long exposure sequence.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need a flattener?\u003c\/strong\u003e For imaging with a larger sensor, yes — the f\/5 to f\/7 flattener suits this telescope and we stock it.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eA 4-inch FCD-100 apochromat in a carbon fibre tube with a GoTo mount included, giving longer focal length and more aperture without a heavy setup to carry. Our team in Bolton can advise on the flattener and camera train that suit your sensor.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53955324641391,"sku":"ES-FCD100-102-CF-IEXOS100","price":3603.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/cftelebundleesmount.png?v=1785951278"}],"url":"https:\/\/ontariotelescope.com\/collections\/es-fcd100.oembed","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}