Cut corners on ground glass

Gloria's post about ground glasses and the responses thereto got me

to thinking...dangerous, I know...nobody ever told me how you use the

cut corners to check your lens coverage, even though I've been

shooting LF for quite awhile. Can someone give us some pointers on

how to use these cut corners for something other than letting air out?

It's my understanding that the cut corners allow for previewing whether or not there may be vignetting - if you have no issues with this then it's a moot point & not to bother.

 

If your camera is fairly airtight then perhaps the bellows can release the air via the cutouts.

 

My assumption is that it depends on your camera.

 

Good Luck

Look through the cut corners at the opening on your lens. If you can see the entire circle of the aperture, you are not vignetting. If the opening is "cut off" from your point of view, then the image is not fully reaching the corners of the negative and you're vignetting.

Thanks, y'all. I recently bought a lens with little extra image circle, so this might prove to be really useful info!

I was reading about this in "the camera" yesterday. It said you can also check for vignetting by looking backwards through the lens. If you can see the entire rectangle, you're not vignetting. Does anyone use this technique? I'm going to try this next time I get a chance - the cut corners really are bothersome for me.

I use this method all of the time when I'm shooting with a wide-angle lens. I don't like to stop down any more than I have to, so I'll set up a shot that I think will get me full coverage and then look thorugh the coners. If I find that the aperture is slightly bloked I'll stop down a stop or two to get the image into the corners. It works amazingly well. Try making it a part of your routine for a little while and I'll bet that the cut corners will stop bothering you pretty quickly. When I shoot with my 8x10 I definately miss them.

Vick: Just look through the cut corner to see the stopped-down aperture of the lens. If the aperture is cut off by the rear lens barrel, or you can see the front barrel through the aperture, you'll have vignetting. If you can see the entire aperture, and nothing but subject through it, all is well.

 

Gloria, I use both methods depending on which seems more convenient. Either accomplishes the same thing.

 

FWIW, Adams (St. Ansel) said the reason for the cut corners was to let air escape when the bellows were suddenly compressed, and said nothing about using them for anything else. I suspect that using the cut corners to check for vignetting is one more instance (among many) where a new usage was later found for a feature that was originally put there for something else. This makes even more sense when we realize that we can check for vignetting from the lens' side of the camera.