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Old 28-05-2016, 01:11 PM
tim.stephens (Tim)
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tim.stephens is offline
 
Join Date: Sep 2015
Location: Brisbane Australia
Posts: 62
This might sound a little confusing but I have found on my RC8 that an off-centre flat, appropriately stretched and acquired can imply that you should look for tilt in your images. However, I find it generally misleading to use to collimate a telescope correctly - this should be done with a star field, collimation tool etc.... as you say. Following from that, the opposite can also be true - a perfectly centred flat can be obtained from a poorly collimated scope in the case of the RC8.

So, if the flat is not symmetrical, probably a good idea to look for tilt in that particular direction but if your star field is perfect, then don't bother and keep shooting. CCDinspector can be useful in this situation.

This can also be caused by imaging train/focuser tilt. This is much easier to see and fix first I would think...

Hope that helps!

Tim

Edit: I used to think the same about wasting good nights but I found it was worse to try to collimate without a star field (daytime) and then discover multiple nights were wasted by poor collimation. Better to dedicate a few nights upfront as 'collimation/bug fixing sessions' and then be happy for months after and produce high quality images consistently and easily.
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