{"product_id":"takahashi-fsq-85edx-babyq-85mm-f-5-3-petzval-astrograph-ota-with-1-01x-flattener","title":"Takahashi FSQ-85EDX BabyQ 85mm f\/5.3 Petzval Astrograph OTA with 1.01x Flattener","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FSQ-85EDX — known as the BabyQ — is Takahashi's 85 mm Petzval quadruplet astrograph, sold here as an optical tube assembly bundled with the 1.01x flattener. At 450 mm focal length and f\/5.3 in a 535–613 mm tube, it weighs 3.6 kg and covers a 44 mm image circle. With the included flattener fitted the system runs 455 mm at f\/5.4 with just 56.2 mm of back focus, which is what makes the flattener worth bundling rather than buying separately.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you want a small, genuinely flat-field quadruplet for wide-field deep-sky imaging — four elements in four groups control field curvature and colour across the full 44 mm circle without the compromises a doublet or triplet design makes at this speed. Its 3.6 kg weight and 535 mm collapsed length make it a strong travel astrograph, and the 50 mm drawtube extension gives the focuser room to work with different camera and filter-wheel combinations.\u003c\/p\u003e\u003cp\u003eVisual observers get a genuine apochromat at prime focus with a diagonal and eyepiece, though the FSQ-85EDX is built and priced around imaging. Tell us your camera and filter setup and we will confirm the flattener spacing works for your train.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePetzval quadruplet:\u003c\/strong\u003e four elements in four groups, an ED apochromat design built to control field curvature and colour across a flat field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e450 mm at f\/5.3:\u003c\/strong\u003e in a 535–613 mm retractable tube, 95 mm across (114 mm dew shield).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.01x flattener included:\u003c\/strong\u003e 455 mm at f\/5.4, 44 mm corrected circle, 56.2 mm back focus — the configuration this kit is built around.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e3.6 kg:\u003c\/strong\u003e light enough for portable and travel mounts once a full imaging train is attached.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e50 mm of drawtube extension\u003c\/strong\u003e for focus travel across different camera setups.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e197.5 mm of back focus at prime\u003c\/strong\u003e — before the flattener is fitted, ample room for accessories.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FSQ-85EDX objective is a four-element, four-group Petzval quadruplet built around ED glass — a design that inherently controls field curvature better than a doublet or triplet at the same speed, because the rear element group does the flattening work a separate corrector would otherwise need to do. The bundled 1.01x flattener refines that further, correcting the field to 44 mm at 455 mm and f\/5.4 with 56.2 mm of back focus — tight enough that camera spacing needs to be accurate, and generous enough that most imaging trains reach it without extension tubes.\u003c\/p\u003e\u003cp\u003eOther conversion options exist for the FSQ-85EDX platform — the RD QB 0.73x reducer brings it to 330 mm at f\/3.9, and the EX ED 1.5x extender to 680 mm at f\/8.0, both with the same 44 mm circle — though this kit is built and priced around the OTA-plus-flattener configuration.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWide-field deep-sky imaging:\u003c\/strong\u003e at 455 mm and f\/5.4 with the included flattener, a 44 mm corrected circle across the frame.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTravel astrophotography:\u003c\/strong\u003e a 535 mm collapsed tube and 3.6 kg weight suit portable rigs and checked baggage.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFaster, wider framing:\u003c\/strong\u003e with the RD QB 0.73x reducer (sold separately) at 330 mm and f\/3.9.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTighter framing:\u003c\/strong\u003e with the EX ED 1.5x extender (sold separately) at 680 mm and f\/8.0.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eBack focus is 197.5 mm at prime, dropping to 56.2 mm once the included 1.01x flattener is fitted — the figure your imaging train needs to hit. Takahashi's system charts for the base configuration, the RD QE 0.73x reducer and the EX ED 1.5x extender are in the Downloads tab, with the exact parts and distances for each. Our \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e collects the same figures for the whole range in one table.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlattener:\u003c\/strong\u003e 1.01x, included in this kit — 455 mm at f\/5.4, 44 mm circle, 56.2 mm back focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReducer:\u003c\/strong\u003e RD QB 0.73x (sold separately), 330 mm at f\/3.9, 44 mm circle, 72.2 mm back focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtender:\u003c\/strong\u003e EX ED 1.5x (sold separately), 680 mm at f\/8.0, 44 mm circle, 117.5 mm back focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMount:\u003c\/strong\u003e sold as an OTA with flattener — no mount, rings, dovetail, diagonal or eyepiece included. At 3.6 kg plus a full imaging train, most travel and mid-payload mounts handle it.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eIf you are not sure your camera and filter thickness will reach 56.2 mm exactly, send us your imaging train and we will work out the spacing with you.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThis is an optical tube assembly with the flattener included.\u003c\/strong\u003e Mount, rings, dovetail, diagonal and eyepiece are sold separately.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBack focus with the flattener is tight.\u003c\/strong\u003e 56.2 mm is generous by imaging-train standards but still worth checking against your camera and filter wheel stack.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe reducer and extender are sold separately.\u003c\/strong\u003e This kit bundles only the OTA and the 1.01x flattener; the RD QB 0.73x and EX ED 1.5x are additional purchases.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTube length varies with the dew shield position.\u003c\/strong\u003e 535 mm retracted, 613 mm extended — worth accounting for in a case.\u003c\/li\u003e\n\u003c\/ul\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. The flattener is included and matched to the tube, so reaching the 56.2 mm back focus is mostly a matter of using the standard adapter stack. The published system chart in the Downloads tab confirms the exact parts, and we can check your specific camera train against it.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eWide-field deep-sky imaging — nebulae, star fields and Milky Way regions — at 455 mm and f\/5.4 across a flat 44 mm circle.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the kit include everything I need to image?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt includes the OTA and the 1.01x flattener. A mount, camera, and any filter wheel or guider are separate purchases.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it visually?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes, at prime focus with a diagonal and eyepiece, though the telescope and this kit are built and priced around imaging use.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the difference between this and the reducer or extender configurations?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThis kit is built around the 1.01x flattener at 455 mm and f\/5.4. The RD QB 0.73x reducer (330 mm, f\/3.9) and EX ED 1.5x extender (680 mm, f\/8.0) are separate accessories for wider or tighter framing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should this not be the choice?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIf you need faster than f\/5.4 without buying the reducer separately, or a longer native focal length than 450 mm offers before adding the extender.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: an 85 mm Petzval quadruplet astrograph and its matched 1.01x flattener, together giving 455 mm at f\/5.4 with a 44 mm corrected circle and 56.2 mm of back focus. It weighs 3.6 kg, collapses to 535 mm for travel, and is built for wide-field deep-sky imaging.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eOptical Diagram Reports\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes a spot diagram for the FSQ-85EDX with the 1.01x flattener fitted — the configuration this kit ships in — showing star images across the field at the design wavelengths.\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FSQ-85EDX_FL101X_spots.png?v=1786911643\" alt=\"Takahashi FSQ-85EDX 85mm Petzval spot diagram with 1.01x flattener\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047058559087,"sku":"TAK-TQE08541","price":4919.2,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/TQE08541_FSQ-85EDX_OTA_1.jpg?v=1786912043","url":"https:\/\/ontariotelescope.com\/products\/takahashi-fsq-85edx-babyq-85mm-f-5-3-petzval-astrograph-ota-with-1-01x-flattener","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}