Battling Vignetting

[Jeff_4368]

In Q.-Tuan Luong's "A step-by-step guide to operating the view camera" he mentions:

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# Check for vignetting (optional but recommended). This should be the last step before closing the lens, as vignetting might be due to lack of lens coverage or to obstruction by filters, shade, or bellows, and should be checked at taking aperture

* Through the corner cut-out of the groundglass look at your wide open lens: the aperture will look somewhat like a cat's eye pupil. Now slowly stop down until your the lens opening shape changes into a round opening in which you see all the aperture blades. This is the largest stop at which you will have no vignetting.

* Check top and bottom is you used rise/fall or tilt. check left and right if you used lateral shift or swing. * If necessary, straighten the bellows and take care of sag.

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I have an Ebony 4x5 field camera, and have been disappointed with some shots where some vignetting has ruined the corners of my shots. Unfortunately, my ground glass doesn't have the "corner cut outs" that might make determining whether any vignetting is occuring easier. When I am stopped down to a very small aperature, it is impossible to ascertain how much, if any, vignetting is occuring.

I take alot of pictures of buildings and structures that demand a lot of rise, which means that I need to push my lens close to the edge of it's image circle, but, of course I don't want to shade the corners of my film!

What can I do?

[Capocheny]

Jeff,

The obvious thing to do is to have the corners cut out of your groundglass and any competent glass shop should be able to do that for you at a very minimal cost.

I was in the same situation and this is what I did...

Cheers

[Capocheny]

Jeff,

The obvious thing to do is to have the corners cut out of your groundglass and any competent glass shop should be able to do that for you at a very minimal cost.

Cheers

[Jeff_4368]

I guess with the "cut outs", then determining vignettings is pretty simple?

Bill Maxwell, of Maxwell Precision Optics is a family friend. I was thinking of commissioning him to build a new screen for me, as an upgrade to the Ebony screen. I guess he could take care of the corners for me....

[tim atherton]

Not quite as convenient, but look from the front looking from below through the aperture to the opposite top corner of the GG and from the top to the bottom corner

[Scott Soper]

Like Tim said: view through the front of the lens. With no film holder in place or focusing cloth covering the GG, it's usually pretty easy to tell if you can see all 4 corners of the GG or not. If you can, then you're good to go!

[Jeff_4368]

I hadn't even thought of looking in from the front! I would have thought that would be difficult with tiny aperatures, but, I guess not?

Thanks!

[Jim Rice]

This is so cool. Thanks Tim and Scott.

[tim atherton]

As I say, not quite as convenient - basivally you are peering though (as Scott said, with no film holder or dqarkcloth) looking to see if you can see all four corners of the gg through the full "circle " of the aperture (and most of the time, if youa ren't using any sideways shift, you really only need to do one top and one bottom)

My deardorff used to have cut off corners and I tended to use them quite a bit, but since I got the Phillips, which doesn't have them, I just tend not to bother... I guess I've got used to how much coverage my lenses have - what catches me out every now and then is using a very wide angle and not hooking up the bellows with the velcro tab so they don't vignette.

[Scott Soper]

Yeah, my bellows tend to sag too. Much easier to see through the front of the lens.

[Bruce Watson]

Lot's of good answers. You could also go for lenses with more coverage. With the 110mm SS-XL and my Toho, I've never seen lens vignetting. I have pushed the rise so far as to induce bellows vignetting however...

[N Dhananjay]

I dislike cutout corners since I like to see what is in the corners. So, I just take the back off and check for vignetting. Cheers, DJ

[ronald moravec]

For horizontal- raise the lens 1.5 inches and shoot a picture with detail in the corners. for vertical- raise the lens 2 inches and shoot a picture with detail in the upper corners. after processing, you will be able to see when darkening occures AND when acceptable definition is lost. If you lost the top 1/2 inch , subtract that from the amount of rise you used. Record that on a sticky label on the lens board. If you are cropping or working in close up, you may be more generous, If you are tilting down, this costs coverage. You have more rise in horizontal format than vertical unless you are using square format.

Invest in a lens with good coverage, they are worth every penny.