The Jewel of Winter shot from my rooftop observatory in downtown Houston, Texas.
This image also served as a bit of a test between Edge HD8 native Ha data vs Askar 120APO data shot at 840mm then cropped to match the Edge FOV. I've often shot nebulae with refractors then done significant crops to show some fine details, and often wondered if much shorter focal length refractor could keep up with a longer optic whose design is a bit long in the tooth. The short answer is for the most part, yes. I'm intrigued by the prospect of being able to use the much less fussy refractor to make images of close up details like the Edge can do.
Below are a few comparisons between the Edge HD8 at its native focal length (left) and the 120APO at its native configuration of 840mm and f/7 (right)
Each image is 1.5 hours of Ha data, and the only processing done on both is background extraction, stretch to non-linear, and HDRMultiscale Transform to tame the core. The refractor data on the right is not drizzled - it's normally stacked subs cropped in to match the Edge.
To my eyes, I see three things:
1-some stars render better on the frack, some on the Edge (especially in the trapezium). It's probably a wash here
2- zoomed out, overall nebulosity detail is about the same from each optic
3-the refractor has a bit more noise (for the most part trivial, and easy to overcome with more data and a bit of processing)
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