Your prediction is correct bojan I have had the fridge down to -12C with ambient at 3C and 100% relative humidity and still no noticeable condensation on the sensor. I know that the sensor heats up while taking long exposures compared to the camera just simply being on. All cold metal surfaces were wet everywhere else.
Will keep adding info in case someone else wants to try it. No sense reinventing the wheel.
Bert
here is an image all frames taken with fridge at -11C.
http://members.optusnet.com.au/~trlee8/corA_ehdr07.jpg
Thread here
http://www.iceinspace.com.au/forum/s...ad.php?t=21178