Quote:
Originally Posted by peter_4059
Rick - sounds like you think it is a mechanical issue? I've had the dial gauge on the focuser and stepped it in and out and get very reproducible results.
I suspect it is the HFR calculation or variation in HFR due to SNR, guiding error or something else. I've seen reference to flat v-curves from fast optical systems in the Focusmax manual. I also notice the Focusmax V-curves recommend 30-40 points and aim to get a large variation in HFR over the curve.
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I haven't thought about it deeply, Peter, because I've never had much trouble with automated focus. A couple of things I've noticed are that I generally get better looking V curves on faster/shorter FL systems (even the same system with a big reducer) and that just being in the CFZ is not good enough. I've always assumed that the first effect is due to the greater impact of seeing at longer FL.
Have you thought about playing with an eval copy of FocusMax 4? (or one of the earlier free versions.) Might be an interesting experiment.
Cheers,
Rick.