keeping your camera cool

[oldpink]

I know that in general its best to keep your camera cool but how cool and how to achieve it without going to extreme lengths

tonight as its cloudy and wet I have the scope set up in the room going through some software and settings to get used to what they all do
when I messed about with some 10 sec exposures with the dew shield on the scope to mimic taking darks I had lots of noise with the ASI120
so I put the camera in the freezer for 10 minutes and took it down to -3 deg put it back in the scope and took 40 x 10 sec exposures starting at -1 deg, last frame was 14 deg

quite a big difference in the noise levels as you can see

I've seen people mount cooling fans etc but are they effective enough to make the hassle of extra power and weight worth while

[lensman57]

What you are seeing is thermal noise. All CCD and CMOS sensors get hot in use, after all current is supplied to the circuit. In an ideal world all this heat should be removed and as you have discovered getting it subzero will clean the image up to a great degree. There are however two problems here, 1, without active cooling the sensor will warm up again particularly if you go into real long exposure, 600~1800s per sub. 2, the camera must have provisions to resist the moisture built up as a result of cooling and the innards must have been desgined  with this in mind. Repeated cooling of cameras such ASI 120, I have both the MM and the MC, or a DSLR will eventually result in failure. Atleast in the case of the ASI 120 I have an email from the designer of the camera  to the same effect, I believe they are considering sealing the chamber and instigating active cooling at some stage as per Atik, QHY and other cooled ccd cameras. This is particularly true if super cooling to -30C is used, however in case of the new generation of Sony ICX sensors, below -15C very little changes as noise is pratically none existant. The owners of the ASI 120s could perhaps employ a cold finger and a magnetic levitation fan to remove the heat to great extent and reduce thermal noise with the caveat that even opening the case will invalidate the gurantee.

A.G