Quote:
Originally Posted by MarkInSpace
Hi
I have a skyrover 115mm refractor and the sky rover flattener. I’ve just installed a brand new asi2600m camera and I am having lots of difficulty achieving a flat field and focus. ....
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Hi Mark,
I had a look at your image and my first thought is that it seemed like a reducer type issue, but you mentioned a flattener only, but looking at the image seemed it was too wide a field of view for your 805mm (115mm f/7) focal length, since you have
a flattener fitted. I checked on Stellarium and it's more consistent with something around 600mm, suggesting maybe you have a
combination flattener and reducer fitted (???). If that's the case, then the reducer will see closer to the edges of the image circle than just a flattener AND coupled with the larger sensor diagonal of the 2600mm (28.3mm) compared with the 294 (23mm) will show more of the outer image circle a lot further outward (~22% more).
If it really is a flattener & reducer fitted then, maybe its position in the image train needs to be fine tuned for optimum results. Also in reading I noticed somewhere a backfocus of 54.8mm recommended
Best
JA