Problems with processing a wide-field Milky Way image

So, no calibration frames at all? To me this does look like some vignetting is going on. I would try to make a flat with that setup just to verify if that might be the case, you can immediately see it in the flat then as well.

I have calibration frames. But stacking only two frames with just a slight vignetting shouldn't result into this, don't you agree? I normally make flats just by pointing the telescope at early morning sky, but this is not possible with this lens as it is too wide. So I have made calibration frames by shooting a white monitor 50x. I have attached a single flat (downsized) and this is a link to master calibration files: https://drive.google.com/file/d/1yCqp2TU0wFIR2YZtpwh4I4C6eznOAtm_/view?usp=sharing

Using flats actually makes the situation worse.

I might try today with f2.8, which should only have 0.6 stops of vignetting in extreme corners. But I don't think this current data is useless if I look at single light frames.

A white monitor doesn't have to be very good at that, it depends on if you have a panel that sends out broad spectrum light. Flats also need to be calibrated with a master-bias. But, I'll have a look at the data tomorrow, would be nice to find out what the actual issue is.

@vincent-mod Thank you.

One explanation for the PhotoShop images having no vignetting might be that you have automatic Lens Correction Filter turned on in PS.

@jgwyther I have provided 20 RAW files. You can check those. I don't think I have done any vignetting correction to the image above - just colour correction.

Hi Samo,

So I loaded in 1 frame and stretched it a lot (all in APP). No processing, just stretching and what you can see is vignetting indeed. This is likely because of the housing of the sensor, or maybe the cap on the front of the lens (not 100% sure about that).

The masterflat I can't load in both APP or PixInsight (as in it shows a black screen). Not sure why that is, but at least the fits info shows an exposure of 0.06 seconds, normally it's advised to have this at at least 1-2 seconds per sub. Why I don't see any signal in both programs I'm not sure about, but I wouldn't use it indeed.

 I think @jgwyther is correct in that Lightroom is applying a lens correction.

@vincent-mod Thank you for this. I have recorded also data with f2.8 and it looks a lot better. Can be corrected without flats. And I normally shoot flats like this and don't have problems. Didn't know about 1-2s requirement.

Yes, also make sure the histogram of the flats is nicely at around 50-70% without clipping, then it should work fine.

I have found one workaround that is time and disk space consuming, but it works without flat frames: I have converted cr3 subs to tiff files so that peripheral illumination information gets baked into files and stack those. This are three frames stacked from the test set I have provided above. It would be a great thing if APP would support this. This would make processing extremely wide-field photos much easier.