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Old 08-11-2021, 02:36 PM
JA
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JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 3,052
Quote:
Originally Posted by Mickconn77 View Post
Finally collimated and tilt adjusted my C8 and the field curvature is quite substantial, even with the 0.63 corrector/reducer.
Have included the diagnosis from CCDI (please note the image was cropped unintentially) and the severity of the coma is quite apparent. Does this seem standard for this scope?
What correctors would be recommended? Starizona may be too expensive, Alan Gee (confused about its application).
Quote:
Originally Posted by Mickconn77 View Post
Yeah I’m using the same sized sensor on a 1600mm which makes me think I’ve got something gravely wrong.
Hi Mick,

Maybe you are doing nothing wrong. Perhaps look for uncropped Astrobin images using a 0.63x reducer on the C8 with a 1600mm sized sensor to be sure. The images may point you in one direction or another in terms of understanding the root cause of the image edge quality issue.

In any event, using a focal reducer, whilst making for a faster scope will mean you see more of the image circle than you may wish to, revealing all sorts of foibles at the edge of the image circle, even on the relatively modestly sized 4/3 sensor of the 1600mm. I'm not sure another brand of 0.6ish-X focal reducer would help that much, on that sized sensor (~22mm diagonal). Also, perhaps consider trying/researching a 0.8x reducer.

Best
JA

Last edited by JA; 08-11-2021 at 03:01 PM.
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