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Hi Pete, A couple of things seem to be happeneing here. It aoppears to be an exposure problem. On one hand to much exposure showing up in the extremely black dust donuts, bright centre and backgound and the hardest thing to correct is the length of exposure required due to the slow shutters found in most 8300 CCD cameras.
The problem stems from the camera taking its own sweet time to take the image even when a very short exposure is selected due to the slow shutter.
The problem is fixable but it will require you to extend your exposure time out beyond the 0.2 of a second exposure time to get beyond the min exposure time of the shutter.
You may have to either darken the LED by adding a sheet or two of paper to the Light box appature or dimm it down more if possible. 2X2 binning certainly won't help but is required so maybe appature darkening is best.
Make sure you get your Intensity value in Maxim out to about 12 to 15 read at the bottom of Maxim as you drag the mouse around the brightest parts of the exposure. It can take a while to get these figures worked out and will be different for each filter.
I had a look at your posted flat and although only an 8 bit image with intensities from 0 - 255 your brightest areas are about the 225 level which seems a bit high. I would have expected a maximum of about 130 for a good 8 bit flat.
Remember yours from the camera will be 16 bit not 8 bit so target figures of 20 to 30 thousand should be targeted.
Good luck.
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