Rowland that's a damn good result.
I managed to get my 450D (in side a peltier cooler box) to 0C~-4C but it takes nearly 3/4hr to 1.2hrs to reach this. Thus while my box works it's a real pain in running it and is a little ungainly attached to a focuser. I also had thermal losses thru the focuser drawtube (had to insulate it)
Thus I ask, what time period does it take for you to obtain for full temp drop? I'd expect much faster than my box and thus I'd be more than interested it all this.
Also do you use the Arduino as PWM temp feedback control or just run the TEC flat out and measure the temp?
Are you getting thermal losses thru the camera case or drawtube?
Sorry for all the questions...just interested I am!
Brendan