15-85 opinions

Started Jun 29, 2010 | Discussions thread
J A K Forum Pro • Posts: 15,833
Re: At 85mm the vignetting cannot be corrected by DPP.

Dale Buhanan wrote:

Interesting pictures, Joe. I'm finding that PTlens does a much better job of correcting vignetting and distortion that DPP does. PTlens seems to be smarter and follows the vignetting characteristics a little better and for distortion, it is smart enough it corrects the mustache distortion very well. There is also much more detail preserved. DPP is quite lossy for distortion correction.

Everything depends on either knowledge of the equations for a specific FOV or, in the absence of equations for a typical roll-off characterization via measurements must be utilized. Even if the you had perfect characterization (assuming you found a perfect lens) it wouldn't do you any good because of unit-to-unit variability in the centering at any of the focal lengths (i.e. part of the problem is asymmetric vignetting).

BTW, I own PTlens and agree with your comment above; it's a great program.


Joe Kurkjian

Galleries: http://www.pbase.com/jkurkjia

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