Starfield 2" Coma Corrector (1.1x) for Newtonians f/3–f/6

Starfield 2" Coma Corrector (1.1x) — Sharper Stars Across the Field for Fast Newtonians

Starfield Coma Corrector

Fast Newtonian telescopes are incredible for deep-sky imaging—but at faster focal ratios, coma becomes obvious: stars that look tight in the centre stretch into “comet” shapes toward the edges. The Starfield 2" Coma Corrector is designed to reduce coma and deliver cleaner star shapes across the field for f/3 to f/6 Newtonians, whether you’re observing visually or imaging with a camera.

Highlights: 1.1x factor • 4-element / 2-group optical design • 43.9mm clear aperture • accepts standard 2" filters • ~75mm (±5mm) imaging spacing target

 

What This Coma Corrector Does

  • Reduces coma so stars stay tighter toward the edges of the frame.
  • Expands your usable field for wide-field eyepieces and modern camera sensors.
  • Maintains a fast workflow with only a small magnification increase (1.1x).

Compatibility

  • Telescope type: Newtonian reflectors
  • Recommended focal ratio range: f/3 to f/6
  • Focuser size: 2"
  • Magnification factor: 1.1x

Modular 3-Piece Design (Visual + Imaging)

This coma corrector uses a modular layout that supports both visual observing and camera setups.

Starfield Coma Corrector

Part 1: 2" Nosepiece with Optics

  • 2" barrel with a recessed safety groove for secure retention
  • 48mm male filter thread so you can add standard 2" filters (LP filters, broadband filters, etc.)

Part 2: 2" Eyepiece Barrel

  • Brass compression ring with dual thumbscrews for a solid hold on eyepieces/adapters
  • Used primarily for visual configurations

Part 3: M48–T2 Adapter Ring (Included)

  • Common pathway to cameras via T-thread systems
  • For DSLR use: attach your camera-brand T-ring (not included)

Imaging Spacing Requirement 

For imaging, correct spacing is critical. Target approximately 75mm (±5mm) from the shoulder of the 2" nosepiece to your camera sensor (image plane). Start at the recommended value and fine-tune based on corner star shape.  73.5mm has been reported to be the sweet spot.

Practical tip: If your camera train is built around a standard 55mm backfocus (common with DSLR + T-ring), you will typically need additional spacing to reach the 70mm target.

Technical Specifications

  • Optical design: 4 elements / 2 groups
  • Clear aperture: 43.9mm
  • Magnification: 1.1x
  • Recommended focal ratios: f/3 to f/6
  • Imaging spacing: ~70mm (±5mm) from 2" nosepiece shoulder to sensor
  • Filter interface: accepts standard 2" filters
  • Included adapter: M48–T2 ring
  • Optics: fully multi-coated
  • Weight: ~7.7 oz

In the Box

  • Starfield Coma Corrector optical nosepiece (2")
  • 2" eyepiece barrel section
  • M48–T2 adapter ring

FAQ

Will this help visually, or only for astrophotography?

Both. Visual users often notice cleaner edge stars with wide-field eyepieces in fast Newtonians. Imagers benefit from improved star shape across the sensor.

Does this change my focal length?

Slightly. This coma corrector has a 1.1x magnification factor.

Where do I measure the 70mm spacing from?

Measure from the shoulder of the 2" nosepiece to your camera sensor (image plane).

Can I use 2" filters with it?

Yes. The nosepiece is threaded to accept standard 2" filters.