Super Cooling SBIG cameras

Hi
This post might be a bit OT. But considering how much effort we put into that signal to noise ratio...

!!! WARNING !!!
The following image could prove disturbing to sensible individuals.

http://pages.videotron.com/astrolo/Cool/Flake.jpg [1]

Let start by the results. The following is a comparison of two identically
treated and displayed darks taken at 0C and -50C. Notice the shape of the
histograms. The standard deviation of the pixel stats. And finally the overall
esthetics of the frames.

http://pages.videotron.com/astrolo/Cool/darks.jpg [2]

How to...
The principle is simple. But the lack of space in the camera makes part
selection critical.

http://pages.videotron.com/astrolo/Cool/peltier.jpg [3]

At around -30C the optical window fogs up and ice crystals form on the CCD chip.
Heat wire and neoprene insulation takes care of the optical window.

http://pages.videotron.com/astrolo/Cool/Heat.jpg [4]

A dry gas purge takes care of the CCD. Space is so restricted that I had to
install the intake needle valve on top of the desiccant plug.

http://pages.videotron.com/astrolo/Cool/purge.jpg [5]

I did not want to be stuck renting high pressure tanks so I use Argon/Nitrogen
wine preserving gas.

http://pages.videotron.com/astrolo/Cool/wine.jpg [6]

How cold can it go? No idea. I chickened out at -60C and the temperature was
still dropping like a stone. Anyways I can only reach around -50C before the
onset of fog and ice on the optical surfaces.

http://pages.videotron.com/astrolo/Cool/Close.jpg [7]

I can't wait for the next clear night to see how the new results will compare with my previous TT ari time series.

Thanks
Juan Herrero
http://pages.videotron.com/astrolo/ [8]