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Old 09-10-2018, 11:31 PM
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astronobob (Bob)
Casual Cosmos Capturer

astronobob is offline
Join Date: Jun 2010
Location: Gold Coast SE QLD
Posts: 3,870
Originally Posted by multiweb View Post
Cool - so that means you need to center your spider vanes, then put an A4 piece of paper inside the tube and move the secondary up and down the tube and orient it until it looks like a circle centered in the focuser draw tube. Try to ignore all the reflections from the primary.
That's Correct.
Did this with my 8" F4 last night. Then an 'out-of-focus star test' showed 2ndry obstruction in center (One Step Forward) but is somehow producing a double shadow from one of the spider veins, no biggy & hopefully twiddle it right next time or see how it corresponds with a focused exposure 1st ..
Mmmm, the plot thickens !

I am also changing cameras, the zwo 290 chip is way to small
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