I asked about this once before without too much luck. Let me try again.
I need to correct distortion from my 18-200 mm lens for my Nikon D80.
I can experiment with the controls until I get what looks reasonable,
but it would be easier if I could find recommendations for settings of
the lens distortion filter at different focal lengths for the lens.
I used to use a Panorama Tools plugin for gimp for which I found such
recommendations, but I can't get that plugin to work with recent
versions of gimp.
Of course I can experiment by photographing a grid at different focal
lengths and different subject distances and using trial and error, and
create myh own tables. But, I hope someone has already done that.
Finally, where can I find a description of the the algorithm that the
filter uses. If I had that, it might simplify things. Usually these
algorithms apply a polynomial (usually cubic) correction based on the
radial distance from the center of the image. The parameters set the
coefficients of the polynomial.
Leonard Evens l...@math.northwestern.edu
Professor Emeritus, Department of Mathematics, Northwestern University
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