Cost, generosity of creator, ease of use, constant updates for life.

Stand-alone version cannot process RAW files.

There are two version to this very useful, inexpensive and constantly updated program: a stand-alone version, and a plugin for photoshop. I have the stand-alone version, and it has allowed me to correct multiple distortions from different lenses given that it provides you with a HUGE data base of cameras and lenses from different companies. For example, the high barrel distorions of my Canon 17-85 IS USM ----specially at 17mm--- were easily corrected in a matter of seconds. But the program not only allows for corrections such as barrel distorion, it likewise allows for correction of Chromatic Aberrations in lenses such as the Canon 85 1.8 which ---though a true gem--- suffers from high chromatic abberation at 1.8.

Perhaps the only drawback of the stand-alone version is that you cannot correct raw files. The plugin does allow for this type of correction in RAW. However, thanks to Tom Niemann's generosity this program is extremely inexpensive (now $15) and for many years it was absolutely free! If you compare it to the cost of DxO, then there is really no competition. Niemann even compares his program to DxO on this site! He writes:

" Question. How does PTLens compare with DxO Optics Pro?

Answer. For distortion correction of distant objects (10 feet to infinity) results obtained from PTLens are similar to results from DxO. Both PTLens and DxO can process fisheye images, correct perspective distortion, and complex lens distortion such as moustache distortion. DxO has automatic corrections for vignetting and chromatic aberration (CA). PTLens has manual adjustments for vignetting and CA. DxO offers additional features including raw conversion, adjustments for distance, exposure compensation, noise reduction, and volume anamorphosis. DxO costs $79 (prosumer), $149 (SLR), and $299 (full frame SLR). PTLens costs $15."

Customer Service

Excellent