Question for photographers – light fall off

SH
Posted By
Steve Hoffmann
Oct 31, 2003
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1262
Replies
11
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Closed
I had a chance to play with Photoshop CS and the new Camera Raw program has a very nifty tool for controlling vignetting or light fall off in the corners of a photographic image. Unfortunately, this tool only works with RAW file formats. This phenomenon becomes very apparent in large format photography with wide angle lenses. I’ve been trying to figure out a way to use the gradient tool to eliminate the dark corners of my scans. I’ve come close to getting the effect I want but I was wondering if any of you photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans. TIA!!!

Steve

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N
nospam
Nov 1, 2003
In article <0iCob.128844$>, "Steve Hoffmann" wrote:

I had a chance to play with Photoshop CS and the new Camera Raw program has a very nifty tool for controlling vignetting or light fall off in the corners of a photographic image. Unfortunately, this tool only works with RAW file formats. This phenomenon becomes very apparent in large format photography with wide angle lenses. I’ve been trying to figure out a way to use the gradient tool to eliminate the dark corners of my scans. I’ve come close to getting the effect I want but I was wondering if any of you photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans. TIA!!!

I’ll be watching for the definitive answer which _works_, but nothing, but nothing I’ve tried suits my critical requisites. The task concerns more than simply applying a graduated filter-effect. The contrast has to change accordingly, and not necessarily in a linear manner. Underexpose the edges, or overexpose the center… not a good thing. (I’m still looking for the proper graduated ND for one particular lens. They are not all equal.)
BV
Bart van der Wolf
Nov 1, 2003
"Steve Hoffmann" wrote in message
SNIP
I’ve been trying to figure out a way to use the gradient tool to eliminate the dark corners of my scans.

A simple radial gradient (e.g. layer in Overlay blending mode) is probably not accurate enough, but adding a curves correction to it should allow to come close. Adding some noise will reduce posterization in 8-bit/channel images.

Alternatively one of the Panorama Tools plug-ins could assist, but that is a trial and error process (http://www.tawbaware.com/maxlyons/pano12ml.htm).

Bart
T
tacitr
Nov 1, 2003
I’ve been trying to figure out a way to
use the gradient tool to eliminate the dark corners of my scans. I’ve come close to getting the effect I want but I was wondering if any of you photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans.

You’re using the wrong tool for the job.

Select the corners, either by using a radial gradient in Quick Mask mode, or by making a heavily feathered oval selection and inverting it. Then, correct the underexposure with Image->Adjust->Curves.


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JH
John Houghton
Nov 1, 2003
"Steve Hoffmann" wrote in message
I was wondering if any of you
photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans. TIA!!!

Slight vignetting is not hard to deal with, but severe cases are much more challenging. I don’t have to deal with very bad vignetting myself, but even so, you have to take care to avoid banding effects. I’ve described my method here:
http://homepage.ntlworld.com/j.houghton/vignette.htm

John
RF
Robert Feinman
Nov 1, 2003
In article <0iCob.128844$
says…
I had a chance to play with Photoshop CS and the new Camera Raw program has a very nifty tool for controlling vignetting or light fall off in the corners of a photographic image. Unfortunately, this tool only works with RAW file formats. This phenomenon becomes very apparent in large format photography with wide angle lenses. I’ve been trying to figure out a way to use the gradient tool to eliminate the dark corners of my scans. I’ve come close to getting the effect I want but I was wondering if any of you photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans. TIA!!!

Steve
I have a tip on my web site for a way to deal with this. It even works with 16 bit images (although it’s a bit convoluted). One of things I find that helps is to shoot negative film and give the recommended exposure to the corners and allow the center to become overexposed. The latitude of the film will handle this and there is not as much problem with low contrast in the corners.

Look under the tips section on my home page.


Robert D Feinman
Landscapes, Cityscapes and Panoramic Photographs
http://robertdfeinman.com
mail:
S
support
Nov 2, 2003
On Fri, 31 Oct 2003 18:21:11 -0600, (jjs) wrote:

In article <0iCob.128844$>, "Steve Hoffmann" wrote:
I’ll be watching for the definitive answer which _works_, but nothing, but nothing I’ve tried suits my critical requisites. The task concerns more than simply applying a graduated filter-effect. The contrast has to change accordingly, and not necessarily in a linear manner. Underexpose the edges, or overexpose the center… not a good thing. (I’m still looking for the proper graduated ND for one particular lens. They are not all equal.)

Steve (jjs), I’m looking for a challenge for my next graphics program.

Please send me details of exactly what sort of plugin/program would help you do this at throwaway(at)ransen.com….


http://www.ransen.com/
Repligator – Easy graphics effects
Gliftic – Easy decorative tilings
N
nospam
Nov 2, 2003
In article , (PR) wrote:

Steve (jjs), I’m looking for a challenge for my next graphics program.

Do you want original negatives to work with? I can give you various samples, from images with _gross_ (unmitigated ugly) fall-off to the ‘norm’ to very slight. (eg; early 47mm Super Angulon on 4×5", the same on 6x9cm, and ‘blad SWC images.)
W
westin*nospam
Nov 3, 2003
"Steve Hoffmann" writes:

I had a chance to play with Photoshop CS and the new Camera Raw program has a very nifty tool for controlling vignetting or light fall off in the corners of a photographic image. Unfortunately, this tool only works with RAW file formats. This phenomenon becomes very apparent in large format photography with wide angle lenses. I’ve been trying to figure out a way to use the gradient tool to eliminate the dark corners of my scans. I’ve come close to getting the effect I want but I was wondering if any of you photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans. TIA!!!

Panorama Tools includes a tool to deal with this.

<http://www.path.unimelb.edu.au/~dersch/>
<http://home.no.net/dmaurer/~dersch/Index.htm>


-Stephen H. Westin
Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors.
SH
Steve Hoffmann
Nov 6, 2003
Thanks for all the useful suggestions!! The problems with some of them is that you don’t necessarily need the same amount of correction for each corner. If you’ve moved the LF lens for rise fall, shift or tilt even a tiny amount, or if the composition is ‘just so’, you may need slightly different corrections for each corner of the image. Here’s the best quick and dirty I could come up with….

http://www.sphoto.com/techinfo/wdtech.html#Gradient

Thanks again for all the helpful suggestions….

"Steve Hoffmann" wrote in message
I had a chance to play with Photoshop CS and the new Camera Raw program
has
a very nifty tool for controlling vignetting or light fall off in the corners of a photographic image. Unfortunately, this tool only works with RAW file formats. This phenomenon becomes very apparent in large format photography with wide angle lenses. I’ve been trying to figure out a way
to
use the gradient tool to eliminate the dark corners of my scans. I’ve come close to getting the effect I want but I was wondering if any of you photographer/Photoshop users have figured out a good routine with the gradient tool to eliminate light fall off (vignetting) in the corners of your scans. TIA!!!

Steve

N
nospam
Nov 6, 2003
In article <s8hqb.17522$>, "Steve Hoffmann" wrote:

Thanks for all the useful suggestions!! The problems with some of them is that you don’t necessarily need the same amount of correction for each corner. If you’ve moved the LF lens for rise fall, shift or tilt even a tiny amount, or if the composition is ‘just so’, you may need slightly different corrections for each corner of the image. Here’s the best quick and dirty I could come up with….

http://www.sphoto.com/techinfo/wdtech.html#Gradient

Quick and clean is buying the correct graduated filter for your lens. There’s no other way. Do it right.
SH
Steve Hoffmann
Nov 6, 2003
I would if I were positive I’d get perfectly even exposure from center to edge. And, I may end up going that route. You said yourself you were still looking for the ‘proper’ ND filter for one of your lenses. At $200+ per filter, experimentation would be expensive….:^)

Quick and clean is buying the correct graduated filter for your lens. There’s no other way. Do it right.

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