Just update on the Argon bag use. Last week I spent four nights imaging up at the dark site at Bretti NSW, and the camera stayed in the same bag the whole time. You may remember that I flushed it with Argon when I put it into the bag (via the port I made on the side). The only change from the test setup was that I slit the bag slightly in one spot and refreshed the Argon in the bag before the first night.
The nights dropped from 6C to about 2C by midnight, and there was heavy dew there that shut down some of the others that did not have adequate dew protection. The external surface of the bag did get dew on it but there was nothing internally. Simply wiping the external surface of the bag kept the Liveview screen usable. I had the cold finger controller set for -10C and it stayed there for four or more hours at a stretch each night. That temp required minimal power consumption and I noticed that it held -10C for quite some time before kicking back on (no doubt due to the cold soak at that point and the low ambient).
I kept a dew heater strap wrapped around the focuser barrel to prevent the front screw in Baader UV/IR Cut filter from fogging up on the outside (inside the adaptor barrel was filled with Argon, between the filter and the Baader coma corrector, as was the space behind the adaptor).
My images subs came out great, with no evidence of frost, condensation, etc.
Re power consumption, in the dark site field you will need a good size 12V battery to drive the cold finger (TEC, temp controller/fan assembly, etc). I worked out that about 82AH would be needed for a typical night assuming 6AH requried by the TEC). I took a 100AH battery just to drive the camera cooler gear and it was overkill but better to have too much. I found that by holding the sensor at -10C there was minimal power usage at that ambient temp, and the sensor would sit at -10C for most of a five minute sub before turning on again.
After the second night run I again refreshed the Argon in the bag as a contingency, but there had been no sign that it was necessary. Over the four nights, the camera cooling system performed very well, and I had a fair amount of image data - unlike my mate who was trying to get his expensive QSI camera to work.
If you'd like to see a couple of the images, they are here: (first is Eta Carine, second is M83 - which is cropped and stretched so has some evidence of noise which I did not clean up)
http://www.astrobin.com/full/180326/0/
http://www.astrobin.com/full/180325/0/
Excuse the processing as I am still coming to grips with that aspect of imaging, could be better for sure.