A quickie comparison of thermal signal (and its consequent noise) in 3 Canon cameras that I use for astrophotography, all modded, though that is an irrelevancy for this exercise. Each camera was used at room temperature, estimated at around 27deg C, to shoot one dark frame 20 minutes long, inside a camera bag (to minimise the chances of any light getting into it) and ISO 1600. The frames were then converted from Raw using Canon DPP (Digital Photo Professional) with Daylight White Balance, Standard Picture Style and all other settings at neutral, nil sharpening, using NORMAL conversion, i.e. not LINEAR. If Linear conversion is used the frames are practically all black with a very few hot pixels. Note that explanatory text is displayed below each slide in the gallery. The 500D is the same camera as the T1i.
