Sky-Watcher 2" Aplanatic Coma Corrector (SKU: SW-5417) is a four-element optical corrector designed for Newtonian telescopes with focal ratios around f/4. It effectively reduces coma produced by a parabolic primary mirror, keeping stars sharp and well defined even near the edge of the image field. The optical design uses high-quality ED low-dispersion glass (FPL-51) to achieve excellent correction while preserving the native image scale of the telescope.

Key features

• aplanatic coma corrector designed for fast Newtonian telescopes around f/4
• four-element optical design using ED glass (FPL-51)
• effective coma correction without introducing a Barlow effect (1x magnification)
• no additional spherical aberration introduced by the corrector
• image circle up to 28 mm, suitable for APS-C or smaller sensors
• standard backfocus of about 55 mm compatible with DSLR cameras
• M48 × 0.75 photographic thread and 2" barrel for easy installation in a focuser

Box contents

• Sky-Watcher 2" coma corrector
• protective caps

Technical specifications

• type: aplanatic coma corrector
• intended for: Newtonian telescopes around f/4
• optical construction: 4 elements
• glass type: ED (FPL-51)
• magnification (Barlow effect): 1x
• backfocus: approx. 55 mm
• image circle: 28 mm
• photographic thread: M48 × 0.75
• barrel diameter: 2" (50.8 mm)
• corrector length: 100 mm
• focal plane shift: +8 mm
• warranty: 24 months

The corrector significantly improves edge-of-field star shapes in fast Newtonian telescopes, allowing astrophotographers to obtain sharp and well-corrected images across the entire camera sensor.