Don't worry… nobody was hospitalized. We’re talking about coma—an optical aberration that all Newtonian reflectors, including our Skyward 150, exhibit in wide field views.
The Problem: Coma in Fast Newtonians
Coma makes stars near the edge of the field look like tiny comets, stretching away from the center. It’s an inherent issue with parabolic mirrors, and while it’s mild in long focal ratio scopes (f/6+), it’s quite noticeable in faster ones like our f/5 Skyward 150.
The effect varies with eyepiece focal length:
Low-power, wide-field eyepieces show coma the most. A 20mm to 30mm eyepiece will reveal stretched stars near the edges.
Higher magnification, shorter focal length eyepieces reduce coma’s impact because they show only the central portion of the light cone.
Our Simple Approach: A 2-Element Coma Corrector
We’ve designed and will be testing prototypes of a straightforward 2-element coma corrector in the coming weeks—nothing fancy, just an effective way to clean up the field without adding excessive bulk or complexity. We hope to release this as an open source design that you can 3D print and assemble yourself!
Unlike premium multi-element correctors designed for astrophotography which cost several hundred dollars, our goal is to provide a practical, affordable option for much less.
We’ll share more results as testing gets underway!
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