Rosette Nebula

[Rowland]

Marco. If you are using the PI DSLR workflow it is outdated, and frankly, poorly informed, at the time of writing. It was perhaps a step in the right direction. I suggest adopting a different workflow to get the best out of your data, aside from any acquisition errors, which are somewhat fixed, unless new sets can be obtained. Looking at the first image, it is clipped. This is a trap in PI, which as I discovered is geared toward 16bit CCDs. I would encourage a different approach for DSLRs in PI http://forum.startools.org/viewtopic.ph ... =721#p2952 - currently the last post. I am no where near a computer at the moment to have a look at your more recent submissions, but will out of interest in the coming week - if I get time. Upcoming astro camp!

[MarcoS]

Marco. If you are using the PI DSLR workflow it is outdated, and frankly, poorly informed, at the time of writing. It was perhaps a step in the right direction. I suggest adopting a different workflow to get the best out of your data, aside from any acquisition errors, which are somewhat fixed, unless new sets can be obtained. Looking at the first image, it is clipped. This is a trap in PI, which as I discovered is geared toward 16bit CCDs. I would encourage a different approach for DSLRs in PI http://forum.startools.org/viewtopic.ph ... =721#p2952 - currently the last post. I am no where near a computer at the moment to have a look at your more recent submissions, but will out of interest in the coming week - if I get time. Upcoming astro camp!

Hi Rowland, thanks for the post, I have checked out the link you posted, and mostly what you explain is the way I am working, the difference is in the bit where you say:
" Calibrate the lights with the master dark and master flat only"
I was calibrating the lights with the bias as well....
I will try again the stack and see if it gets better.

In the mean time I did process a new stack imagined in two session M63 the sun flower galaxy (with the same scope/camera setup) here also I had Flat darks and bias they are 58 x 300sec light frames.
I did the calibrating stacking etc of each session separately, and then I mergemosaic the two in PI. I had some troubles with the second stack that did not want to align correctly, but by changing some parameters I got it right at the end.

The resulting linear fit I opened it up in StarTools, and with the usual work flow I got this out......

[Rowland]

Hi Marco.

I tried dark flats as well, mainly an intuitive approach, but I found that it made things worse. It seems the least preprocessing the better. The bias in the dark method is age old and tested. Somehow DSLR imagers have been swept up in the 16bit paradigm to disastrous effect.