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Old 01-02-2014, 09:16 PM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,824
Originally Posted by Bassnut View Post
OK, well thats interesting. Someone else explained this to me painfully before too (he takes 1 hr subs). I understand the other factors that can make longer subs difficult, but youve renewed my interest. I might actually try and take say 2hr subs when I can and see if it makes a difference (in my stupid need-to-try-to-believe mind). I know that in dark skies, read noise is always the dominating factor.
OK Fred. yep, I know I can be painful, but I mean well Increasing the sub length should make a noticeable SNR difference - got to be worth a try?

Originally Posted by RickS View Post

Your calculation gives 1695 ADU for my camera. I have got good results for dim targets (the jets of NGC 1097 et al) with 20 and 30 minute luminance subs which have background signals in that vicinity (1600 to 1800 ADU just from a few quick measurements).

wooah, thanks Rick. I had some reservations about posting at all in case I had stuffed up - appreciate the positive feedback.

It really seems to be a very easy way to systematically set exposures based on first principles - do one simple calculation for your camera, remember the result and aim for it thereafter. regards Ray

Last edited by Shiraz; 04-02-2014 at 07:35 AM.
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