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Darks temperature matching


Clive
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The darks and lights are obviously very sensitive to temperature so close matching between the temperature of the darks and lights is critical for good calibration results. Now, when I create my master dark from the individual dark images I use median stacking and for my lights I use kappa-sigma stacking (which after doing it's statistical rejection, averages the result). So the software removes the median value of all the individual darks from each light before doing the average.

Now the EXIF data from my DSLR shows considerable variation in temperature over the duration of the exposures (due to various causes such as if I use Liveview, or cooling down from taking the camera outside or just the drop in the nightime temperature). So my thought is, if the median temperature of the darks matches the average temperature of lights, you should end up with the optimum result. That would mean I could take darks at different temperatures and mix them  such that the median temperature was the same as the average temperture of the lights and so achieve an 'ideal' result.

Well it appears to work on a spreadsheet and the first test on my M31 image that I have been struggling with are encouraging but ...  ?

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If you can Clive  with a dslr dither between frames and you don’t need darks just bias and flats saves a lot of time 

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My polar alignment (or lack of it!) means that I effectively naturally dither. I'll try just stacking frames alternate (or less) images to see if that gets rid of the 'smears'. Unfortunately my current mount backlash means that it takes ages for PHD to settle down after making a move, certainly longer than my typical exposures.

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