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Sky-Watcher Esprit 120EDX Flattener
The Sky-Watcher Esprit 120EDX Flattener is the dedicated field flattener for the Esprit 120EDX Super APO triplet refractor. Like every refractor, the 120EDX brings starlight to focus on a slightly curved surface, so stars toward the edges and corners of a flat camera sensor fall out of focus and stretch into short streaks. Installed between the focuser and the camera, this flattener produces a flat focal plane across a 44mm image circle, keeping stars sharp from the center of the frame to the corners of large sensors.
A 44mm Image Circle for Full-Frame Sensors
A full-frame sensor measures 36 x 24mm, with a diagonal of 43.3mm. The 44mm image circle of the Esprit 120EDX Flattener covers that entire diagonal, so it supports full-frame cameras as well as APS-C and smaller sensors. In practice, this lets large modern sensors be used with the 120EDX while keeping a flat field across the frame.
Matched to the 840mm f/7 Esprit 120EDX
A field flattener has to match the focal length and field curvature of the telescope it corrects, which is why Sky-Watcher makes a separate flattener for each Esprit EDX model. This one is designed for the Esprit 120EDX, a 120mm f/7 air-spaced triplet with FPL-53 glass and an 840mm focal length. It is sold separately from the telescope.
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Which telescope is the Esprit 120EDX Flattener designed for?
Sky-Watcher lists it as compatible with the Esprit 120EDX Super APO triplet (120mm, 840mm, f/7). The other Esprit EDX models each have their own dedicated flattener: the Esprit 70EDX / Evostar 100EDX Flattener, the Esprit 100EDX Flattener and the Esprit 150EDX Flattener.
Will it work on the earlier Esprit 120ED (without the X)?
Sky-Watcher only lists the Esprit 120EDX as compatible. The earlier Esprit 120ED triplet uses its own correctors, so contact our team before pairing this flattener with any other telescope.
Does the flattener cover a full-frame camera?
Yes. Its 44mm image circle is larger than the 43.3mm diagonal of a 36 x 24mm full-frame sensor. APS-C and smaller sensors sit well inside the corrected field.
What back focus does the flattener require?
Sky-Watcher has not yet published the sensor spacing and thread specifications for this flattener on its product listing. Contact our team before ordering and we will confirm the spacing and adapters needed for your camera.
Do I need the flattener for visual observing?
No. Field curvature mainly affects flat camera sensors, where stars at the edge of the frame lose focus. The flattener is intended for astrophotography.
Is the flattener included with the Esprit 120EDX?
No. Sky-Watcher's Esprit 120EDX manual states that the field flattener is purchased separately, which lets visual observers buy the telescope alone and imagers add the flattener when needed.
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| UPC |
810098970778 |
| Optical Specifications |
| Type |
Field Flattener |
| Image Circle |
44mm |
| Compatibility |
| Compatible Telescope |
Sky-Watcher Esprit 120EDX |
| Telescope Aperture |
120mm |
| Telescope Focal Length |
840mm |
| Telescope Focal Ratio |
f/7 |
| Product Information |
| SKU |
S20218 |
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Esprit 120EDX Flattener
× 1
- Sky-Watcher 2-Year Limited Warranty
