Re: Another Digital camera question

On Sat, 14 Jul 2007 19:47:38 -0500, William Hamblen
<wrhamblen@xxxxxxxxxxx> wrote:

The big advantage the better astronomical cameras have over digital
cameras is that the astronomical camera is cooled to a low temperature
to reduce the thermal noise or dark current added to the signal. You
can take longer exposures with a cooled camera before the thermal
noise gets too bad.

And the reason that's an advantage is because for short exposures,
readout noise is dominant- whether you have a digital camera or the best
astronomical camera. If there were no readout noise, you could build
your image out of many short exposures with no penalty at all (but you'd
still have problems with dark current noise, so you'd still need a
cooled camera).

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
.

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