The new Orion 2″ Photo-Visual Coma Corrector for Newtonians minimizes the coma inherent in fast Newtonian reflectors with focal ratios from f/3.5 to f/6.
Coma appears as flared, comet-shaped stars and gets progressively worse farther out from the center of the field. This coma corrector greatly reduces this effect as well as the effects of field curvature, rendering sharp stars across the entire field of view or image frame. The 2″ Photo-Visual Coma Corrector works for astrophotography as well as for visual observing with an eyepiece.
The optics are contained in a 2″ nosepiece, which is threaded into the upper housing that features an eyepiece holder for 2″ eyepieces. The eyepiece holder has a non-marring brass compression ring and two thumbscrews. The bottom of the nosepiece is threaded for Orion 2″ filters. The third component is an M48-to-T2 (M42) adapter ring, which is useful when using the Coma Corrector for astrophotography.
For astrophotography use, you unthread and set aside the upper housing and use only the optics-containing nosepiece. The Coma Corrector’s back focus is about 75mm. For DSLR use you’ll need a 20mm spacer ring to achieve proper image focus. For astronomical cameras additional spacing will be required, the amount of which can be determined by factoring in your camera’s sensor position relative to its front flange.
For visual use some additional spacing may be required for certain eyepieces. As Orion notes, “Some users report that adding 0.75″ (19mm) of spacing between the upper housing and optical nosepiece allowed perfect focus with their wide-field eyepieces.”
The Orion 2″ Photo-Visual Coma Corrector produces a 1.1x magnifying factor. The optics are fully multi-coated for maximum light throughput and it weighs 11.3 oz. You can learn more here.
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