Even at maximum fisheye correction (-0.500 of something not defined in application or site), it cannot correct as much as other tools out there. Is there a way to correct beyond this seemingly arbitrary number to something greater, like -.75? Should I be submitting this as a bug (here?) if there is not? Thanks!
Ubuntu 20.04’s default version of RT (5.8)
https://rawpedia.rawtherapee.com/Lens/Geometry
You can use an LCP or lensfun profile to correct the distortion.
Thanks, but that looks like a lot of work, since I’m constantly trying out new (well, old adapted, really) lenses. I’m more looking for a rawtherapee adjustable control, not submitting a building shot to LCP for whichever lens i’m currently working with and getting a result later (they state it takes this amount of time: “please give us time for this”).
Yes, its a lot of work for everyone: the people who build RT, the people who build lensfun, and the people here to answer your questions 
Touché ! 
I understand that it’s more more work, but sometimes I don’t even remember which lens was on which adapter…
I may look at my raw photos quite some time after shooting them (I’m not a pro, and documenting everything and using the best lenses and going over my photos immediately). I often wonder if I had my EF adapter with my friend’s sigma 8mm f3.5, or if I was shooting with my cheap 7.5mm f2.8 directly attached to my OM-D… having an entry in the LCP would be great for lenses that I’m often using, but I would get more use out of a way to adjust in RawTherapee. I was hoping someone would say “oh, go into some directory and edit some file so that it says -1 to +1 instead of -0.5 to + 0.5.”
We can change that to [-1.0;1.0], but I would like to get a raw-file to test with.
I, too support this change, for rough approximate de-fishing. Maybe a tangent function modified slider response, or something more sophisticated?
@heckflosse, I am assuming you would like me to take a photo of a building (like LCP asks for) with a very wide angle lens, and then post the *.raw file here?
A raw file where the current [-0.5;0.5] range is not sufficient would be enough to test.
