GSO 2" Coma Corrector for fast Newtonian Telescopes
Key Features:

Modular design comprising three components:
(i) Optics housed in a 2" nosepiece with a 48mm male filter thread,
(ii) 2" eyepiece barrel for attachment to the optical nosepiece,
(iii) M48 - T2 adapter ring.
Optimization for use at f/4.5, with reliable performance ranging from f/3 to f/6.
Effectively reduces coma and field curvature for improved image quality.
Suitable for both visual observation and astrophotography applications.
Minimal magnification factor of 1.1x preserves image fidelity.
Fully multicoated optics consisting of 4 elements in 2 lens groups, ensuring exceptional light transmission.
Generous clear aperture of 43.9mm (1.73") for maximum light gathering capability.
2" nosepiece features a smooth barrel and is compatible with standard 2" filters.
Secure attachment ensured by brass compression ring and dual large thumbscrews on the 2" eyepiece barrel.
Back-focus spacing requirement of 75mm with a tolerance of +/- 5mm.
Usage Instructions:

For visual observation, connect the 2" eyepiece barrel to the main optical nosepiece. Additional spacers may be required to achieve the necessary back-focus distance.
For astrophotography, detach the 2" eyepiece barrel and attach the included M48-T2 ring to the main optical nosepiece. Subsequently, connect your DSLR camera to the male T2 thread via a camera-specific T-ring (not included). Additional spacers may be needed between the corrector and your camera's T ring to ensure proper CCD plane alignment.
Canon/Nikon DSLR camera users (with a 55mm backfocus including a standard thickness T-ring) will require an approximate 20mm long spacer (not included) for optimal performance.