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Many thanks Ray for the advice, particularly your outline of how to assess an optimal exposure time. I'll be using a Star Adventurer on an EQ3 Tripod with PHD guiding and was thinking of typically 15 minute exposures though with your advice I could probably drop it to 2 or 5 minutes - I'm doing the mesurements and the math!
I'm a bit puzzled about how to interpret dark current vs. noise. What I see when I run darks with the Atik, the Orion G3 or the ASI120 is a progressive appearance of more and more 'hot pixels' at progressively higher intensities. Is that noise or dark current? I'm using dynamic range to indicate the onset of hot pixels until saturation. So 256 means that there are a large number of hot pixels at an intensity of 8bits and so on until full saturation is all pixels alight at an intensity of 16 bits. I don't know how to express this properly because I've never seen how dark exposure measurements should be quantified and documented? Would appreciate any advice on this you could suggest.
Re your other excellent suggestions I'm following through by phone with Starlight Express as their internet web page doesn't work for me. And have been receiving excellent feedback. Re using the Atik or the Ultrastar, here's my rationale for what its worth.
For power I'm using a minigorilla with a capacity of 6AH at 5v and 3AH at 12V together with a folding solar panel that can completely recharge the minigorilla in a few hours. My estimate is that the Atik will last two to three hours and I'm testing it right now! The Ultrastar should last 30 hours which is a bit more practical for several days camping but it should be feasible to use the Atik for a half night session.
Again many thanks, Peter
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