{"product_id":"sky-watcher-esprit-70edx-evostar-100edx-field-flattener","title":"Sky-Watcher Esprit 70EDX \/ Evostar 100EDX Field Flattener","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThis is Sky-Watcher's dedicated field corrector for two telescopes: the Esprit 70EDX and the Evostar 100EDX. A refractor objective brings light to focus on a gently curved surface; a camera sensor is flat. The flattener resolves that mismatch, so stars hold their shape out to the frame edges instead of drawing short radial streaks in the corners while the centre stays sharp.\u003c\/p\u003e\n\u003cp\u003eSky-Watcher publishes it as a 1.0X flattener with a 44 mm corrected image circle. The 1.0X figure means it corrects without reducing: focal length and focal ratio stay at the telescope's native values. The 44 mm circle encloses the 43.3 mm diagonal of a full-frame sensor and covers APS-C with margin to spare, so framing decisions come down to focal length rather than to how much of the sensor the corrector actually reaches.\u003c\/p\u003e\n\u003cp\u003eThe dual fitment is worth reading carefully, because Sky-Watcher's naming runs close together here. This part is published for the \u003cstrong\u003eEvostar\u003c\/strong\u003e 100EDX — the ED doublet. The \u003cstrong\u003eEsprit\u003c\/strong\u003e 100EDX, the super-apochromatic triplet, has its own corrector (S20217).\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThis is the corrector Sky-Watcher pairs with the Esprit 70EDX and the Evostar 100EDX, and it is the right part if you own either telescope and want flat, round stars across a large sensor at the scope's native focal length and ratio.\u003c\/p\u003e\n\u003cp\u003eOn the Esprit 70EDX — published by Sky-Watcher as 70 mm aperture, 455 mm focal length, f\/6.5 — that means very wide fields with corners that hold up: large emission nebulae, star fields, comets, mosaics. On the Evostar 100EDX doublet it means a longer-focal-length field with the same corner correction across a full-frame sensor.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMatched to two telescopes:\u003c\/strong\u003e Sky-Watcher publishes compatibility with the Esprit 70EDX and the Evostar 100EDX. The correction is computed for those objectives rather than sold as a universal flattener.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.0X flattener:\u003c\/strong\u003e no reduction. The telescope's native focal length and focal ratio carry through the corrector unchanged.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e44 mm corrected image circle:\u003c\/strong\u003e the published figure covers a full-frame sensor's 43.3 mm diagonal and leaves APS-C well inside the corrected zone.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSingle-piece corrector:\u003c\/strong\u003e one optic in the imaging train between focuser and camera, with no separate elements to align.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOne part for a triplet and a doublet:\u003c\/strong\u003e Sky-Watcher publishes the same corrector against the 70 mm Esprit triplet and the 100 mm Evostar doublet, so a two-telescope setup built from those models needs one flattener rather than two.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat it corrects:\u003c\/strong\u003e field curvature across the imaging field of the Esprit 70EDX and the Evostar 100EDX. The visible symptom it removes is corner stars that elongate radially, pointing away from the frame centre, while the middle of the frame focuses cleanly.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorrected image circle:\u003c\/strong\u003e 44 mm, as published by Sky-Watcher. Sensor coverage follows directly from that number — a full-frame sensor measures 43.3 mm corner to corner and an APS-C sensor roughly 28 mm, so both sit inside the corrected field.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMagnification factor:\u003c\/strong\u003e 1.0X. Sky-Watcher publishes no reduction, so the Esprit 70EDX continues to image at its published 455 mm and f\/6.5 with this part in the train, and the Evostar 100EDX at its own native figures.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRequired backfocus and thread interface:\u003c\/strong\u003e Sky-Watcher does not publish a backfocus distance in millimetres or a thread size for this corrector on its product page, and no manual or datasheet is linked there. Those two numbers determine how the corrector spaces to your sensor, and corner star shape is what depends on getting the spacing right. Send us your camera, filter drawer or filter wheel and any adapters and we will lay the train out with you before you order.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWide-field deep-sky astrophotography:\u003c\/strong\u003e on the Esprit 70EDX at 455 mm, large emission nebulae, open clusters, comets and star fields fill the frame with corners that stay clean.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLonger-focal-length imaging on the Evostar 100EDX:\u003c\/strong\u003e the same corner correction applied to the doublet's field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLarge-sensor imaging:\u003c\/strong\u003e the 44 mm circle supports full-frame and APS-C cameras, including cooled astronomical CMOS bodies in those formats.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMosaic panels:\u003c\/strong\u003e flat corners let adjacent panels blend without a ring of distorted stars at every seam.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNarrowband and broadband alike:\u003c\/strong\u003e field curvature is a geometric error, so the correction applies regardless of the filter in front of the sensor.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eSky-Watcher lists two compatible telescopes for this corrector: the Esprit 70EDX and the Evostar 100EDX. The name similarity across their range is the thing to watch — the Esprit 100EDX triplet takes S20217, the Esprit 120EDX takes S20218 and the Esprit 150EDX takes S20219, each published against its own tube. Tell us the exact model printed on your telescope and we will confirm which corrector belongs on it.\u003c\/p\u003e\n\u003cp\u003eThe vendor does not publish the thread interface or the spacing distance to the sensor, so the adapters between this corrector and your camera cannot be specified from published data. Send us your camera model, filter wheel or drawer, and any off-axis guider in the train, and we will map the imaging train and tell you exactly what sits between the two.\u003c\/p\u003e\n\u003cp\u003eNothing about this part changes the mount side of the setup: it adds a short optic and roughly a pound behind the focuser rather than changing how the telescope mounts.\u003c\/p\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\u003eBackfocus is not published.\u003c\/strong\u003e Sky-Watcher gives no spacing figure in millimetres for this corrector. Corner star shape depends on hitting the correct sensor distance, and we can work that out with you from your specific camera and adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread interface is not published.\u003c\/strong\u003e No thread size appears on the vendor page, so the camera-side connection is confirmed case by case rather than assumed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEvostar 100EDX, not Esprit 100EDX.\u003c\/strong\u003e The 100 mm telescope named for this part is the Evostar doublet. The Esprit 100EDX triplet is served by S20217.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe 44 mm figure is published for these two telescopes.\u003c\/strong\u003e Other refractors pair with their own correctors, and the figure is not carried across to them.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a flattener, not a reducer.\u003c\/strong\u003e Sky-Watcher publishes 1.0X, so focal length and focal ratio stay at each telescope's native values.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBox contents are not published.\u003c\/strong\u003e The vendor states no spacer, adapter or case as supplied with the corrector.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight figure is the vendor's shipping weight.\u003c\/strong\u003e Sky-Watcher lists 1.0 lb for this item and publishes no separate optic-only mass in a specification table.\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\u003ePhysically it is one optic that goes into the imaging train between the focuser and the camera, and it stays there. The part that takes attention is the spacing to the sensor, which Sky-Watcher does not publish for this corrector. Send us the camera and adapters you plan to use and we will lay out the train for you.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it fit both telescopes, or do I need two?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eSky-Watcher publishes this one corrector against both the Esprit 70EDX and the Evostar 100EDX. If you own both, this is the single part for the pair.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it change the focal length or focal ratio?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. It is published as a 1.0X flattener, so the Esprit 70EDX images at its native 455 mm and f\/6.5 and the Evostar 100EDX at its own native figures.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it cover my full-frame camera?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe published corrected image circle is 44 mm and a full-frame sensor measures 43.3 mm across the diagonal, so the sensor sits inside the corrected field. APS-C sits well inside it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eI have an Esprit 100EDX — is this the one?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 100 mm telescope Sky-Watcher names here is the Evostar 100EDX doublet. For the Esprit 100EDX triplet the published corrector is S20217. Send us the model printed on your tube and we will match it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat weight does it add to the imaging train?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eSky-Watcher lists 1.0 lb for this item. It is a small addition behind the focuser next to the camera, filters and any guider.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA dedicated 1.0X flattener published for both the Esprit 70EDX and the Evostar 100EDX, with a 44 mm corrected circle — enough to keep stars round across a full-frame sensor at each telescope's native focal length. Sky-Watcher leaves the backfocus and thread figures unpublished, so we confirm the spacing with you against your own camera and adapters and send it out ready to drop into the train.\u003c\/p\u003e","brand":"Sky-Watcher","offers":[{"title":"Default Title","offer_id":53896786083951,"sku":"S20216","price":310.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/100_2_c036ec1b-e071-4037-9437-5adb55294a87.jpg?v=1785253987","url":"https:\/\/ontariotelescope.com\/products\/sky-watcher-esprit-70edx-evostar-100edx-field-flattener","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}