After I learned that my camera is prone to artifacts with backlit photos, I started to examine my photos more closely. Now I have a question regarding Flat-Field correction in RawTherapee.
When applying a FF correction, I have to use Blur type: Horizontal, otherwise the correction image is not aligned with the actual photograph I want to correct. How come? Is it related to the image rotation? I always thought rotations are done by the software based in exif data.
Horizontal always seem to work and remove vignetting, but also introduces a weird pattern in the noise, even at ISO 200, similar to a crosshatch pattern:
Anything I can do about it? Could this be related to the fact that it’s a X-Trans file?