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Chris;
I have been meaning to try
this with my telephotos and Schmidts, but haven't got around to it yet. Grab a
clean white T-shirt and wrap a few layers of it around the front of the Schmidt.
(or telephoto) Install your filters, focus telephotos to infinity and
shoot a cloudy sky, a blank wall, something to give an even amount of light.
Bracket exposures. This should give a nice smooth image of nothing, but will
show the vignetting pattern. Scan the full negative, invert and apply as a
luminance control layer in Photoshop. At some intensity setting, I am guessing
that this will cancel out vignetting. Perhaps the gradient in MaxIm will work
better when it only has one defect to worry about.
I am guessing that this would
work if you scan the full negative, and apply the correction to a full negative
scan of an image. Cropping would change the results. I guess that this
would be the film equivalent of a flat field in CCD work.
Thoughts???
John Mirtle
Calgary, Ab. Canada
(G8 country!)
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