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.
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.
The principle is simple. But the lack of space in the camera makes part
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.
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.
I did not want to be stuck renting high pressure tanks so I use Argon/Nitrogen
wine preserving gas.
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.
I can't wait for the next clear night to see how the new results will compare with my previous TT ari time series.