Re: Comet like Ring nebula, or a planet


"Chris L Peterson" <clp@xxxxxxxxxxxxxxxxxx> wrote in message
news:1r6ci3l5103bjkdq1uf4tdsqikfv8vv655@xxxxxxxxxx
On Mon, 29 Oct 2007 17:36:42 GMT, "MAT" <MAT@xxxxxxx> wrote:

What tempereature in Celsius is optimal for CCD?

Well, in the case of comet Holmes the cooling isn't too critical because
the total exposure time is likely to be short, so dark current noise
will be small. I only suggested that cooled cameras were good choices
because they are specifically designed for high dynamic range, low noise
operation.

In general, dark current drops by half for every 6-7°C of cooling. Dark
current noise (the stuff you can't get rid of) is equal to the square
root of the dark current. For most sensors and most applications, dark
current noise becomes insignificant once the sensor gets down around
-30°C, which is about the limit most thermoelectric cooled cameras are
capable of.


How would this work for a point and shoot CCD or CMOS camera ? Would noise
be
reduced by the same amount?


.

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