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Old 11-11-2013, 03:26 PM
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graham.hobart (Graham stevens)
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positioning of camera with AO8

I am finally going to give my AO 8 with SBIG ST 4000xcm a go as my cooled dslr is not working (see other thread).
My question is this
Currently I achieve focus with three ext. tubes plus feathertouch focuser on my RC 8 with the mono QSI.
If I position the SBIG at roughly the same position would this be presumably at focus point- therefore do you put the sensor there or the front of the AO glass? I mean does the AO 8 matter that it will be ahead of the in focus light cone?
To clarify say the QSI is in focus at 150mm from the RC 8 back plate, should I place the SBIG sensor there to start with or the AO8 glass?
Cheers for any advice- can't really try it as raining but would like to know so I can set up ready.
Graham
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Old 12-11-2013, 05:13 AM
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JohnH
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The ccd sensor needs to be at the focal plane with the AO8 in front if it. The glass in the AO is flat and alters focus point only very slightly (like a LUM filter does) - iirc it shortens focus a tiny fraction.
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Old 12-11-2013, 09:29 AM
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graham.hobart (Graham stevens)
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ao8

cheers mate!
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