Starfield Field Flatteners
Starfield Field Flatteners for Astrophotography
A field flattener is designed to correct field curvature—the reason stars often look sharp in the centre but stretch toward the edges. A good flattener helps deliver pinpoint stars across the frame, especially with today’s larger sensors.
For detailed spacing/setup steps, use the official manual: Starfield Reducer & Flattener Manual (PDF) .
Shop Starfield Flatteners
Starfield 1.0x Field Flattener (Fixed)
A true 1.0x flattener (no focal reduction) for photographers who want to keep native focal length while improving corner star shapes. Designed around 55mm back focus and intended for common refractor focal ratios. Optional M48 adapter support is available for larger imaging trains.
Starfield Adjustable 1.0x Flattener (80–155mm class)
The adjustable version is built for imagers who want easier spacing: set your back focus, lock it in, and fine-tune by adjustment rather than hunting for spacer rings. A strong choice if you frequently change cameras, add a filter wheel/rotator, or rebuild your imaging train.
How to Choose a Flattener (Beginner + Technical)
Start with your goal
- Keep native focal length? Choose a 1.0x flattener.
- Simplify spacing and tuning? Choose an adjustable flattener.
Spacing is everything
Flatteners are optical correctors—small changes in distance to the sensor can change star shapes at the edges. Many systems are designed around 55mm, and adjustable flatteners make this easier when you change camera trains.
Field Flattener FAQ
What is “field curvature”?
Some refractors naturally focus the centre and corners on slightly different planes. Your sensor is flat, so without correction you may see edge stars that look stretched or soft even when the centre is sharp.
Will a 1.0x flattener change my focal length?
No—1.0x means the focal length stays the same. You keep your telescope’s native framing, but improve edge performance.
Do I need a flattener if I use a small sensor?
Often, small sensors crop out the worst edge curvature—so the improvement may be subtle. As sensors get larger (APS-C, full frame), flattening becomes much more noticeable and valuable.