Quote:
Originally Posted by Shiraz
maybe also try an out-of-focus star test and make sure the collimation has not shifted. I imagine that there is a fine line between clamping the lens elements tightly enough and overdoing it to the point of pinching - maybe something is drifting around sightly in it's holder?.
However, I think that field rotation would still be be the most likely explanation
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Thanks Ray. I've never needed to check collimation before, being a refractor guy. I assume I need high magnification for this?
I think rotation due to my RA drift seems likely at this point. PHD warns me pretty much every time I try to calibrate about unexpectedly varying RA & DEC rates and I can see it correcting RA a lot in the same direction.
Quote:
Originally Posted by glend
Lee it is frustrating I know, I am still trying to sort out my Hotech Field Flattener with the ASi1600 on my refractor. Have the spacing exactly as suggested by the instruction sheet but it's out of focus, even allowed for the filter, and sensor coverglass in the path. I suspect the rear corrector element in my scope is buggering up the spacing norms.
Did you adjust the spacing to take into account the filter and coverglass in the path to the sensor? Applying the 1/3 rule? I reckoned that my 2mm filter and the 1mm coverglass (=3mm) required an extra 1mm of spacing. Most flatteners are ok within .5mm aren't they?
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Cheers Glen. It's a pain in the arse, isn't it? I'm actually over 0.5mm with spacing, but I think the 1/3 rule makes that 0.5mm under (that's the way it works, no?) with my LRGB filters. Not entirely sure about the narrowband stuff but I care less about that...