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!)
----- Original Message -----
Sent: Wednesday, June 26, 2002 10:56
PM
Subject: [APML] Gradient and Vignette
removal software
Im looking for a
simple to use piece of software that removes gradients and vignetting from
my schmidt camera images with film. Ive tried Maxim DL, and I get
horrible results, and wondered if there is something I can say put a grid on
and it does what it has to do to flatten the brightness of the grid.
Maybe Im overlooking some thing obvious, but doing this in photoshop is a
gamble at best.