Re-reading the software tutorial, "Master Calibration Frames: Acquisition and Processing" I see where it says to use 10 dark and 10 bias frames to create the master frames. I have for years always taken large numbers of bias frames, usually 60, to create my master bias and usually 20-25 darks at a given temperature and time for masters. I typically image in 10, 20, and 30 minute time ranges depending on which scope and camera/filter combination. So I have always taken my darks by a given temperature in increments of 5 degrees at these time intervals. Last night for instance I was shooting 30 minute subs of M82 using my STL-11000, OGS 12.5" f/9 RC and Ha filter all binned 1x1 at -30 degrees for 30 minute subs. I go into my dark library which is generated usually each season and choose the appropriate master dark to use for calibrating the images. In my case I use temperatures in 5 degree increments and develop the library with the above listed times ending up with -30 degree darks in 10, 20, and 30 minute increments. The same for -25, -20 and so on. This is done on nights where it's not possible to image because of clouds, rain, and so on. So I'm not losing prime imaging time. The biggest thing is the amount of hard drive space this consumes over time.
Now reading the above tutorial it seems to recommend using bias frames and scale the darks for any given time/temperature light frames. Given I already have my dark library and bias frames, is it a real advantage to scrap those and take the calibration frames this way? Or as an experiment is it suggested to take my 30 minute -35 darks and use the bias frames to scale any of the images I'm taking?
I've struggled using PI to calibrate my images and I've always fallen back to using my image acquisition software, MaxImDl, to calibrate my images and then further process the image in PI. As some may know from my website, I dearly love the power and control PI gives me in processing my images but I struggle with some of the processes, Image Calibration being one of the basic ones. I'd really like to conquer issue and keep all my processing totally within PI. So what am I doing wrong? I use the same master darks and master flats files in MaxIm to calibrate and they work extremely well. Using these same files in PI to create the master frames leaves the images not well calibrated. Is using 60 bias frames for a master not advisable? Is using 20-25 darks frames for a master at the given imaging temperature and time not as good as using a scaled master? Should using my lowest temperature darks (-35 degrees) at 30 minutes sufficient to cover any of my images taken at anywhere from -35 degrees for no longer than 30 minutes to 10 minutes at say -15 degrees? Am I asking the right questions?
I should also mention that I take sky flats and usually generate a library of those as well. The master flats are usually made using anywhere from 10-20 individual frames and have the master bias applied. These are no longer than 20 second exposures and have no darks applied.
I'll add to the post by going back and trying to make new masters again in PI and using those on an image and then using my normal MaxImDl process and post the differences I see as an example. I'll post those images to my website so that larger versions can be seen for a better comparison. I have no idea where my process is messing things up and am sure my approach in PI is wrong and I could continue to calibrate in MaxImDl but would rather learn the error of my ways and become more affluent in PI.
Thanks for any assistance given.
