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Frank, like you I went through a lot of this before buying my current camera.
Some pieces of advice I got.
ATS has a formula to work out your sampling rate for any given pixel size. The basic premise is that you need your sampling to be about 2x as good as you average seeing. So in my case I get around 1 arc second of average seeing on any given night. I need to sample at 0.5 arc seconds. The KAF8300 gives me around 0.68 with my RC. However I could use the STL6303 and get better results and still be sampling at a good rate.
In reality though I have read that 0.80 arc seconds is fine for most scopes. The old 2 seconds or arc per pixel seems to be pretty much out. I could be wrong but that seems to be the case.
Well depth - this is how much charge the pixels can take before saturating and more importantly how long you can image for. Any sensor that has a higher well depth is apparently considered as being superior. Sensors that have pixels the size of 7.4 and 9 are considered to have good well depth. The KAF8300 has a well depth of only 5.4um. Not great for star sizes at high mag but good for sampling. You might now be seeing the picture. It also means that you can only image for 10-15 minutes with an 8"RC with that size pixel. Personally, when I buy again I will be looking at a pixel size of 9um to get the better well depth. Star bloat becomes less a of a problem from what I have seen. Stuart's (Rat) images show great stars because he has less bloat caused from larger pixels in his ST10.
Pixel size - related to above but also determines the bloat of your stars or whether you get round or square stars. If your pixels are larger than 9um then you are likely undersampling and this creates square stars (not wanted). If you are using pixels smaller than 9um then you are really over sampling and this creates very round stars but they tend to bloat because more pixels are filled with charge and this gives the stars a larger look. Over sampling is good for image sharpening but no good for star size.
Like I said, the KAF8300 is probably best suited for refractors with its smaller pixels (I will be using mine for the very same thing when I buy the next CCD). Try looking at something around 9um for your RC. Ask Peter Ward or Martin Pugh. I am sure they will tell you the same thing.
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