Hi David - I have been using a Canon EOS 1100D for about 5 years now. I had it modified about three years ago.
I use BackyardEOS (BYEOS) to control the camera, and, it allows you to customize the filename associated with each image. I make sure that the camera temperature is part of the filename. In that way I know what the camera temperature was for each image I take (Dark or Light).
To take darks for my Darks Library, I put my Canon (with the lens cap on and the viewfinder "cap" on) into a plastic ziplock bag which I then put into an insulated lunch bag along with artificial ice. I then use BYEOS to take pictures at the desired ISO and exposure time. By taking pictures as the camera slowly cools down and then slowly warms back up I get many Dark frames at all of the available temperatures. In order to have enough Dark frames at each temperature I usually end up doing two or three cool-down/warm-up runs. All of these runs are made during a day or night when I had available time. They never interfere with nights when real imaging can be done.
Once all of the Dark frames are collected I sort them into folders as shown in the top half of the picture below where temperatures ranged from 46F to 73F.
I have chosen to group my Dark frames to the nearest 5F when making the Master Dark Frames. The 11 Master Dark Frames I created are shown in the lower half of the Picture above. These are almost a year old, but, seem to still be working well. However, I may start working on a new set of Dark frames soon.
It was mentioned that the changing temperature of the
DSLR during a nights imaging can be a problem. I've never found that to be true in my case. I just gather together all the Light frames that correspond to one of the MasterDarkFrames and perform Calibration on them. Then, from the Light frames remaining, I Gather together all of the frames corresponding to another one of the MasterDarkFrames and perform Calibration on them. I continue in this way until all of the Light frames have been Calibrated. This has always worked well for me.
Hope this helps.
Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight ***** My AP website:
www.steveking.pictures