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Canon EOS R Sensor Temperature

Equipment DSLR Dark Frames
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Götz Golla avatar
Götz Golla avatar
I have an astromodified Canon EOS R, which I am using occasionally for taking color photos with my Takahashi E130D. I am also using the ASIAIR to take the pictures. What puzzles me everytime is what sensor temperature it will be this time. In January I made a set of darks with ISO40000. Ambient temperature was about 0C. The sensor temperature displayed was +4.5C during the whole set, and also during the subsequent lights.

Tonight I have a similar setup. I would like to make darks, ambient temperature is about 0C, ISO is 40000. The camera is outside already for 3 hours. But the sensor temperature displayed is +22C ! And it doesnt show any indication to drop.
Has anyone an idea why this could be ?
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Götz Golla avatar
Götz Golla avatar
Since I am just now integrating on SH2-296 I can provide some more information. It turns out that the temperature included in the single frames (FITS images) is different from the one indicated on the screen of the ASIAIR. The temperature of the images wildy varies. It started with 21C, then got down to 7C within 20mins, then got up again to 17C, than got down to 6C, then up again. Its to be almost a period curve with a period of about 1hour.  This is weird.

Of course in this situation it is completelly useless to produce DARKs.
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andrea tasselli avatar
andrea tasselli avatar
Are you really using ISO 40,000? Maybe all this amplification has something to do with it. Besides, the mirrorless Canons are pretty close to be ISO-invariant if memory serves me right. Given that you can't control the temperature of your camera I don't get what is the point of knowing the dark temperature. I go by using an average temperature dark and do cosmetic repairs afterward to get rid of of hot or dark pixels.
Howard Schneck avatar
Howard Schneck avatar
I'm told the temperature that is reported for Canon cameras (at least for mine, a T3) is useless to figure out what temperature your darks should be.  I got told this from a NINA expert.  Another astrophotographer I know who is very knowledgeable said he does even take darks anymore but instead does bias, flats, and dithers his lights.  And that is what I am now doing.