Description
Starfield 1.1x Coma Corrector (2") — Clean Corner Stars for Fast Newtonians
Fast Newtonian telescopes can produce coma—stars that look sharp in the centre but stretch into “comet” shapes toward the edges. The Starfield 2" Coma Corrector is designed for f/3 to f/6 Newtonians to reduce coma and improve star shapes across the field for both visual observing and astrophotography.
Key specs at a glance: 1.1x magnification • 4-element optical design • 43.9mm clear aperture • 2" filter-threaded nosepiece • ~70mm (±5mm) backfocus requirement.
Why You’ll Want a Coma Corrector
- Sharper corner stars for wide-field imaging and large sensors
- More usable field at fast focal ratios (where coma is most visible)
- Better-looking visual views with wide-field eyepieces in fast Newtonians
Compatibility
- Telescope type: Newtonian reflectors
- Focal ratio range: f/3 to f/6
- Focuser size: 2"
- Magnification factor: 1.1x
Mechanical Design (Modular 3-Piece System)
This coma corrector uses a modular design to support both visual and imaging configurations.
- Optics in a 2" nosepiece with a 48mm male filter thread (accepts standard 2" filters)
- 2" eyepiece barrel that attaches to the optical nosepiece for visual use
- M48–T2 adapter ring for common imaging connections
Secure fit: the 2" barrel features a recessed safety groove and a brass compression ring with dual thumbscrews for solid retention.
Spacing Requirement
For imaging performance, spacing matters. The Starfield specification calls for approximately 75mm (±5mm) from the shoulder of the 2" nosepiece to the camera sensor/image plane. 73.5mm has been reported to be the sweet spot.
Practical spacing tip
If your camera system is a standard 55mm backfocus (common with DSLR + T-ring), you may need additional spacing hardware to reach the target. Start at the recommended spacing and fine-tune in small increments if needed based on corner star shape.
Technical Specifications
- Optical design: 4 elements / 2 groups
- Clear aperture: 43.9mm
- Magnification factor: 1.1x
- Focal ratio range: f/3 to f/6 Newtonians
- Backfocus spacing: approx. 75mm (±5mm) from 2" nosepiece shoulder to image plane
- Filter compatibility: threaded to accept standard 2" filters
- Camera/adapter interface: M48–T2 adapter ring included
- Optics: fully multicoated
- Weight: approx. 7.7 oz
FAQ
Will a coma corrector help visually, or only for imaging?
Both. Visual users often notice improved star shapes near the edge of wide-field eyepieces in fast Newtonians, while imagers benefit from more uniform star shapes across the sensor.
Does this change focal length?
Slightly. The coma corrector has a 1.1x magnification factor.
Where is the 75 +/- 5mm mm spacing measured from?
From the shoulder of the 2" nosepiece to the camera sensor/image plane. 73.5mm has been reported to be the sweet spot.
Can I use 2" filters with it?
Yes. The 2" nosepiece is threaded to accept standard 2" filters.