Field Flattener for 480-700 mm Telescopes and 2.5" Focuser (SFF6-25)
Stellarvue
Field Flattener for 480-700 mm Telescopes and 2.5" Focuser (SFF6-25) is a matched reducer/flattener or field corrector for improving star shape and image scale on compatible optics.
Best Current Offer
Specifications
Optics
- Optical type
- Reducer / field flattener
- Threads
- standard 42 mm photographic t-ring
Compatibility
- Compatibility
- 480-700 mm Telescopes and 2.5" Focuser
Use
- Primary use
- Correcting or reducing an imaging telescope field
Sensor / electronics
- Back focus
- 55 mm
Specifications
- Reduction factor
- 1.0x (no reduction)
Astrophotography Fit
Best when it is matched to the exact telescope design and installed at the specified back-focus spacing.
Field Flattener for 480-700 mm Telescopes and 2.5" Focuser (SFF6-25) should be treated as part of the optical prescription, not a generic accessory. The right reducer or corrector can flatten the field, improve corner stars, and in reducer form make the system faster and wider.
Spacing, tilt, and sensor size are the entire game. Even a premium corrector will disappoint if the camera sits at the wrong distance or the focuser cannot hold the train square.
Best paired with
- The specific telescope model it was designed for
- Threaded adapters and spacers that hit the published back focus
- Cameras with sensors inside the corrected image circle
Not recommended for
- Unmatched telescopes with different optical prescriptions
- Rigs where back focus is already consumed by filters/OAG/rotator
- Trying to fix guiding, focus, or collimation issues optically
Where To Buy
Some links on this page are affiliate links. Prices and availability are pulled automatically from each retailer and updated daily.
| Retailer | Price | Availability | View Offer |
|---|---|---|---|
| Cloud Break Optics Cloud Break Optics | $229.00 | In stock Updated 8/5/2026 | View Offer - $229.00 |
Price History
Chronological retailer pricing with out-of-stock points shown at reduced opacity.