Below are a few quick results the first two are OK you all know, the third is the Lamda Neb in Carina and the fourth is IC 443 with some friends IC 444 and at top right a bit of NGC 2174. By morning the ambient temperature was 13C and the fridge was down to -3 deg C. The last two images were six shots for each at four minutes at an ISO of 1600 at f/2.8. For an ISO of 1600 the noise is quite low.
Well I will be stuffed and pickled. I had thought about solving the heat of a DSLR without pulling it apart. So this is how it can be done!
Great images as well.
Lester the coldest thing in the fridge is the peltier heat exchanger and that is where the condensation settles. I have whipped off the fridge when it was 3C ambient and the fridge was at -12C. There was condensation everywhere on any metal surface outside the fridge and the Canon 5DH was dry as a bone. The fan in the fridge really helps here as the air is first drawn over the heat exchanger and then blown onto the camera. This is most important as any residual water vapour will condense onto the heat exchanger rather than the 5DH! The images told me there was no condensation on the sensor.
I take no precautions what so ever with the camera. I know that the sensor is self heating and any condensation will form somewhere colder ie the peltier heat exchanger.
I did these tests in winter which is far more demanding than hot summer nights. Last night the system passed with ease as at the start of the night it was 25C and by morning 13C.
I only put these images up to show that you can collect data on a hot night even at an ISO of 1600!
I still don't have all the answers but I am getting there.
Thanks Leon. My next version will be for refractors. The trick is not to load the imaging train. Might even fit on an FSQ something or other. I will build one for you at nominal cost ie just bits. The fridge itself is cheap. A decent power supply is about $300. The ingenuity priceless!
If you cool the sensor directly you have potentially a very good result BUT it is the coldest thing around and guess what, then water vapour WILL condense on the sensor. You can protect it with a window with antireflection coatings and a dry nitrogen atmosphere etc you may as well buy an SB----!
Our hobby is one compromise after another not only with equipment but spouses! In my madness/quest I will pass on anything I find out.
I am going out now to drive my SLK MERC to the pub to get more beer. Might even take the 16" RC for a run. Oh hell I can't I have to be in Chicago. Gee that was a quick four hours back in SF. Oh well may as well spam a few threads. That will let them know what an idiot I am. No let us just be calm. I think I got away with it! Ok I am not the idiot they think I am. So far so good.
Hold on here is another thread I really know something about. Perfect...
Excellent work for sure.
Whats Canion's official operating temperature range for the camera, its down to 0 degrees isnt it, though for people taking pics in the snow, I bet it would work somewhat below that, though best on external power.
Scott
now where are you going to put the tinnies, some awesome shots Bert. 
