De-fishing a fisheye

Does anyone here have experience with de-fishing a diagonal fisheye on a 5D2?

After cropping to a rectangle, how large an image are you left with? What aspect ratio is the image? And how wide is the remaining image?

I've played with doing it in DxO and PTLens. I have a 5D and a Canon 15mm FE. If you completely de-fish an image, it looks like crap in my opinion unless you crop it so heavily you may as well have just used a much longer lens to begin with. Some light de-fishing can work nicely though.

For most landscape uses, I'd just need to correct the horizontals, not the verticals.

What do you mean it 'looks like crap' - do you mean too much of a loss of resolution, or too much distortion?

When you de-fish and crop to a rectangle, you'd end up with an aspect ratio much wider than 3:2 - more akin to a panorama.

The more you de-fish it, the more stretched the corners get and corners aren't that great to begin with on the 15mm. I use my fisheye as a fisheye and have the 17-40 when I want lines to stay straight. I've done some landscape with the fisheye and depending on composition, it doesn't necessarily look like an obvious fisheye shot as long as I keep the horizon through the middle and there's nothing like a fence post near the edge.

I imagine that picture quality will suffer quite a bit. I have the Samyang 14mm (not a fisheye) and occasionally when I try to correct perspective distortion the sharpness of the image degrades quickly - the correction needed on a fisheye would be even greater.

You could try stitching two UWA images together if you wanted a more normal looking image taken over a wide field of view?

rusty.jg wrote in post #13272341
I imagine that picture quality will suffer quite a bit. I have the Samyang 14mm (not a fisheye) and occasionally when I try to correct perspective distortion the sharpness of the image degrades quickly - the correction needed on a fisheye would be even greater.

You could try stitching two UWA images together if you wanted a more normal looking image taken over a wide field of view?

I do a fair bit of stitching already.

This is for times where stitching isn't practical.