## Re: Dark Library info...

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• I think you misunderstand what the set point on the camera means. If I understand you correctly you seem to think that a set point of -20 means that the camera
Message 1 of 6 , Dec 10, 2012
I think you misunderstand what the set point on the camera means. If I understand you correctly you seem to think that a set point of -20 means that the camera cools -20 below ambient. This is not what happens; a set point of -20 means that the camera chip will be at -20 whatever the ambient temp may be.
Geoff

--- In ccd-newastro@yahoogroups.com, "Dave" <terrarouge@...> wrote:
>
> I had a lot of good info on the darks question I posed earlier but I forgot to ask...If I want to make a dark library..If my camera is set to -20 Celcius...in order to be usefull as a dark on other substhe Ambient temperature should be the same too to be able to use on another sub,correct? Say Camera -20 degrees and ambient -10 degrees for a total of -30 degrees.If it was 0 degrees ambient...I wouldn't be able to use the dark on any other ambient temp.Correct???Thanks and Clear skies...Dave
>
• Actually, if you set -20C in your camera control system, it mean -20C, period, that is, 20 degrees below 0 degrees centigrade, not -20 from the current ambient
Message 2 of 6 , Dec 10, 2012
Actually, if you set -20C in your camera control system, it mean -20C, period, that is, 20 degrees below 0 degrees centigrade, not -20 from the current ambient air temperature. What you do is to pick a temperature that your camera can reach, and stick with it. Depending on where you image and how good your camera can cool, perhaps in summer you can use -10C for all your darks and subexposures, and in winter -20C. The cooling delta that you see advertised with cameras is a delta from the current air temperature. So, for example, an SBIG STL camera can cool about 35 degrees below the air temperature on a given night.

--- In ccd-newastro@yahoogroups.com, "geoff" <ghsmith45@...> wrote:
>
> I think you misunderstand what the set point on the camera means. If I understand you correctly you seem to think that a set point of -20 means that the camera cools -20 below ambient. This is not what happens; a set point of -20 means that the camera chip will be at -20 whatever the ambient temp may be.
> Geoff
>
> --- In ccd-newastro@yahoogroups.com, "Dave" <terrarouge@> wrote:
> >
> > I had a lot of good info on the darks question I posed earlier but I forgot to ask...If I want to make a dark library..If my camera is set to -20 Celcius...in order to be usefull as a dark on other substhe Ambient temperature should be the same too to be able to use on another sub,correct? Say Camera -20 degrees and ambient -10 degrees for a total of -30 degrees.If it was 0 degrees ambient...I wouldn't be able to use the dark on any other ambient temp.Correct???Thanks and Clear skies...Dave
> >
>
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