Done
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Thanks a lot to @heckflosse and @jdc!
Just downloaded RawTherapee_newlocallab_5.8-1964-g0436674b3_20200515. When using Preprocess White Balance mode = Camera the dots are much less prominent than before. Switching to Mono and back to 3-pass lets them disappear completely.
That’s a bug , though an interesting one 
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A nice looking bug 
I hope this is the right thread, I’m not sure if this is the same issue or not. I compiled the lastest dev version and I got this with my X-T30. The Markensteikn algorithm produces strong colour artifacts in high contrast areas in some directions. This was already the case with a version compiled one or two weeks ago. Similar artifacts are visible with all other algorithms. Maybe it’s a problem with the colour pattern itself?
This is less important of course, but the “none” method also doesn’t show the right colour pattern:
This looks like CA to me.
Are there less “artifacts” in the center of the frame?
Wouldn’t CA show up everywhere on the roof, not just in the right slope? And wouldn’t the colours be the same on both edges? Also, this was taken at f/7.1.
edit: wait no you’re right, the colours wouldn’t be the same. But still, I’m not convinced it’s CA.
Using ‘none’ you should also use neutral profile to see the xtrans patterns (so neutral + demosaic none)
Well, I can show you files from my Nikon D700 (bayer) which have a large amount of CA even at f/8.0
Okay I found the neutral profile and that works! I need to read the manual more, I don’t understand what is going on here.
I will do more tests to see if it can be CA. Unfortunately I don’t have other lenses.
Exactly! I thought it had to do with alignment with the sensor matrix, but maybe there is another explanation.
Can you please show where in the frame this part of the image is?
Is your lens the 35/F2?
The 1.4 has quite low CA. This looks strange
Actually it might be transverse CA! I didn’t expect it to be so bad. I have checked other pictures and It looks like the blue is always moved towards the centre of the picture.
I rarely use lensfun or explicit CA correction with this lens. It is simply not necessary there.
Could you post a RAF?
Maybe it’s just a bad copy? CA correction in RT makes it much better even though it’s not completely gone. DSCF0468.raf (28.5 MB)
I just got this lens as well, and I have an X-T20 if you guys need another test point.
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I think you should not use such extreme magnification.
Here is an example of my copy mounted on a X-E2s, also using 1600. The snippet is from far right of the frame:
And this is the same with 100%
There is visible CA, which is being over-corrected by lensfun.
Iridient X-Transformer performs a bit better:
