Originally posted by yeedub So PTLens can fix the distortion well? I've always wondered about the distortion of this lens since the majority of it is in the extreme borders only.
For my copy all of it is in the extreme borders and less than 12mm. At 12mm and up there is no need at all for any distortion correction. I really love that part, having been use to zooms in the 17-## range that had plenty of barrel distortion at 17mm. Its really nice to take a pic at 12mm, 16mm, or 20mm and have them flat.
Now the distortion at 10mm is at the deep corners/borders only so even there with most scenes of outdoor type its nothing of concern. but at times it can cause an un-desirable affect on the pic, especially close up architectural type shots. Moreover most PP programs of any cost can only do corrections in one (maybe 2 but not PS) dimensions. PTlens works in 3 dimensions and can much more accurately and throughly correct complex distortion such as with the Sigma 10-20mm at 10mm. It comes pre-calibrated for almost every lens out today, and you need do nothing but push a button.
I wish I knew of another free program to speak of, but I don't.
Below is a pic I took today of a brick wall at 10mm from ~1m away. First as-is, second with PTlens. You can imagine what it does with regular pics, makes them flat as a board it does
; however I notice a very small crop of about 1-2% of the frame to do it. With most lens it does not have to do that. But it gets the job done, good enough I would say. I have read its based on another program that does corrections in 3 dimensions and the author of PTlens just automated that program to read the EXIF of lens. It then applies the pre-made calibrations from the author of almost 2600 lens, so at least he does work for that money. Nothing wrong with that. But again, I know lots of people only believe in free downloads. As a programmer I don't.
BTW the bottom right is worse than I usually see, IMO it is because I was hand holding the camera/lens and was not perpendicular to the wall.