2026-10-09 APP 2.0.0-beta48 has been released !
This is mainly a bug fix release for the reported bugs in beta47. In addition it has a significant User Interface performance improvement noticable when you need to process 1000s of images in APP.
2026-10-03 APP 2.0.0-beta47 has been released !
This is a very big release... many code optimizations/rewrites, many parts of APP are much faster and more precise, especially star analysis and registration are much faster ! Big mosaics will go much faster 🙂
And we introduce a new preview filter, which includes the new Adaptive Deep Sky Stretch and a General Levels Stretch, this has been long over due. The old preview filter (the panel on the right side to stretch and preview your data) has not been updated for a couple of years and it is a critical part of any APP session.
Adaptive Deep Sky Stretch or ADSS is a much more intuitive stretch algorithm. It is also color preserving (which is a great new addition in itself ! ) which means that the highlights are no longer bleached, color is maintained from the linear data while stretching. You can simply stretch your data using the sky background level and signal width sliders which work much easier and more intuitive. You no longer need to fiddle with the old complicated sliders with zoom buttons. All the zoom buttons for the sliders are made redundant. And you can enter slider values in the slider value fields yourself. I will make a youtube video in the coming days to explain and fully introduce ADSS. Once the video is ready, it will be highlighted on the forum.
RGB Combine upgrade !. The RGB Combine Tool has been rewritten mostly. The tool is faster and easier to use and most importantly, the Luminance slider to inject a luminance channel or channels into the RGB composite is now working correctly. It no longer bleaches the RGB colors. Combined with the new ADSS preview, you will get much better and easier great composites with great color! I will also explain this in a new youtube video.
Hi Mabula,Â
I have a question which might probably not related to something with APP but I am running out of ideas what to do.Â
After applying my flats I seem to have a strange gradient in my images.Â
Here is an image with only BPM and Bias and one after applying the flats:
I can remove this with the light pollution correction tool but it would of course be nicer if the image was more flat to start with.
It probably is no light pollution itself because it appeared on different targets in the same manner and in the same corners.Â
It could possibly be the dark but I also had a similar result when just using the BPM, Dark and flats.Â
The flat itself also looks like it is ok (but I am not entirely sure)
If you have a minute I would greatly appreciate your feedback.Â
In case you are interested here are some lights and the calibration frames I use:
Dropbox File (Private or Invalid)
Thanks in advance
Frank
Â
Edit: Just one addition: When I calibrate one sub with the above files it is seemingly nice and flat but I couldn't check the actual ADU values for one calibrated sub
I also experience this strange flat effect too. However, I learn that if I took new flats for every astrophotography night, and strictly followed workflow in the tutorial video, this problem seem to be lessen.Â
Â
Kijja
I've seen that too. It looks like vignetting. That particular tool in app has never worked for me, so I take it into Lightroom and correct for vignetting and it goes away
Thanks for your replies. The light pollution correction works fine for me but I was just wondering if someone could put me in the right direction where this remaining gradient comes from. Also I fear, when using the LPC tool it might wipe out some possible faint ifn that is still in the data so I would like to go down to the source of this. The flats look exactly like they should look and if I calibrate a single sub it looks nice and flat. However when I then stack the images it there is still some irregular shaped vignetting left on the right hand side of the image. I just can't find any sensible source for that in my OTA or in my calibration frames.
Best Frank
Quick update:Â
I tried several different ADU values for my flats ranging from 12k to 45k with 30k and 45k being a smidgen better. However I think as the vignetting differs so much from the actual flats I was wondering if it could have something to do my sensor glow which at full stretch looks something like this:
I tried calibrating without the Bias frame and just the darks / bpm / flat but the result is still not a lot better.
I really have no clue as to where else to search. As mentioned before the exact same pattern occurs at different angles and bearings of the scope.
Update #2: Seems I found the issue. It is the flats with my ASI. Sorry to bother you... Actually it seems the exposure was to short for my flats. once I dimmed my flat box and added some paper between the telescope and the flatpanel and was able to get above 0.5s for the flats the results got a lot better. Not perfect but quite a lot better. I aimed for the same 30k ADU but just with a longer exposure. Not sure if there is a rule of thumb for that. If anyone knows anything I would greatly appreciate your feedback 🙂Â
Thanks, Frank
Hi Frank @foschmitz,
Yes, exposing flats with very short exposure times can give all sorts of problems, I know that for a fact. Please try to make the flat exposures at least 0,5 sec and preferably longer to achieve even better correction. Some DSLRS have this problem as well like newer Nikons.
The actual gradient that you reported intitially might have come from LNC in integration, that could be the source to introduce this artificially, but then again, it shouldn't either. Perhaps you can test once more without LNC enabled to check if that makes a difference?
Is everything now working fine in calibration?
Cheers,
Mabula
I also experience this strange flat effect too. However, I learn that if I took new flats for every astrophotography night, and strictly followed workflow in the tutorial video, this problem seem to be lessen.Â
Â
Kijja
Yes, shooting new flats if you can will always be better, but sometimes it's hard and you lack time to do so.. If you make flats however , try to have longer exposrue times than a fraction of a second to improve your flats 😉
Flats with very short exposure times can and often will lead to bad flat-field calibration.
Mabula
I've seen that too. It looks like vignetting. That particular tool in app has never worked for me, so I take it into Lightroom and correct for vignetting and it goes away
Vignetting is to be corrected with flats like Frank is trying to do. In that case the correct vignetting tool is redundant. That tool is only for data sets that completely lack flats, only then the tool will be of value to you 😉
Vignetting correction on data without flats actually can be done very well with the tool, (dust bunnies aside, you really need real flats to correct those ... ):
Mabula
