Quote:
Originally Posted by marc4darkskies
Very nice image Greg! Did you do long subs? At a dark site I'd shoot for 30 minutes!
Cheers, Marcus
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You know I probably will do that next time. I was stoked I was getting perfectly round stars at full camera resolution using the MMOAG. The guide scope was a bit hit and miss due to flexure but was OK at short focal lengths.
I also had the camera at -45C, so it is virtually noiseless (its a very clean chip to start with) and it almost doesn't need darks.
I will check that out next time to see if I get a better signal to noise ratio. I used to take 15 minutes as standard.
The only problem with 30 minutes is the fact that the 8300 chip has small wells - only 20,000 electrons. The 16803 has over 100,000!.
What that means is bright stars oversaturate very easily and at 30minutes it may make them look a bit messy plus I might lose colour in a lot of the stars. But 15 minutes should be fine in most scenes.
What's the theory of long subs at dark sites? Lower % of read noise to signal allowing more detail in dim areas? Less overall noise?
Greg.