Astronomical observations are almost always affected by dust on the
window in front of the CCD chip - it shows up as a dark doughnut shape
on the image (research-quality telescopes are all reflectors so it's
that familiar mirror lens bokeh). It's very straightforward to
compensate for this by using a uniform light source to determine
variations in sensitivity across the chip. Ought to be possible to do
something similar with a digital camera if cleaning is not a practical
option.
Roger
John Hermanson wrote:
> I understand the front of the ccd is covered with a thin layer of
> glass.
_________________________________
----- Original Message -----
From: "Mickey Trageser" <vze3m2s8@xxxxxxxxxxx>
>> That is disconcerting. What do the CAN-NIK-FUJ digital SLRs have
>> to protect the CCD? At least with film, you face a new frame of
>> it with each shot.
>>
> With the CCD, the same surface is revealed every time the shutter is
> tripped. I suppose the shutter provides a fair amount of protection,
but dirt will find it's way in there. Sounds like a situation that would
require more frequent CLA. Bet that's expensive.
>>
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