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Strange you are only getting bloat in the blue. That would seem to point towards the filter or the scope.I can't say I have ever seen poor performance of my TEC180 in the blue channel though. Blue is often hazier than the other channels due to light scatter but seems no different to any other scope. As Ray points out this chip is also quite small so the magnification factor is quite high. Again not sure why that would be a problem but it may be magnifying whatever that something that is non optimum here.
I am curious though if my AP140 shows any difference. At least that would nail down the possibilities a bit more.
Another possibility for the bloat may be the microlenses on the sensor. I wonder if they don't like F7 and the angles the rays hit them? A bit of a long shot though.
The UV/IR block aspect may be worth an experiment. I have a Baader UV/IR block filter I could tape on the CCD window to see if it changes anything. Another little test next time I have it out.
I was not too worried about it really as my other cameras suit the style of images I want with this scope and my CDK does better than the TEC180 for galaxies although the TEC180 does an excellent job. The CDK at 17 inch aperture simply is better.
Greg.
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