Quote:
Originally Posted by bartman
Just out of curiosity.... what would one be looking for in the pictures ( that Paul H has posted) in regards to field rotation?
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What you look for with field rotation is that each corner has stars that are curve in a radius eminating from the center. In this case I have provide just two corners on the left side but each corner has the problem. This small amount is not much but it is there and the problem is that I know it is there.
Quote:
Originally Posted by Hagar
I really wonder if your problem is field rotation or just registration problems due to field curvature. Just a thought.
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I don't think it is Doug, well not entirely. There might well be some registration problems, but I don't think these are caused by field curvature. Curvature has that look where stars are pointed toward the center of the image. These are perpendicular and curved from that line. There might be some registration issue worth looking at though.
I noticed that when I put the reducer on this scope this problem became more evident. The reducer may be causing some distortion.
Quote:
Originally Posted by multiweb
To check for minute field rotation the best way is to shoot wide field in Ha so you get tiny stars and pick a guide star right in the corner of your frame and look at the opposing corner. On a 20min subs you're bound to see any rotation for sure.
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I will have to give this a shot to know for certain. Like I said, I don't think it is field curvature as the stars don't really match that pattern. However, shooting longs subs in Ha should give me a definitive answer.
Food for thought guys.