Ebony Camera - How To Check for Vignetting?

On every large format camera I've owned I've always checked for

coverage and vignetting by looking at the aperture through the cut

out corners of the viewing screen. However, the viewing screen on my

Ebony SV45Te doesn't have cut out corners. Has anyone tried cutting

the corners on the Ebony screen, which I believe is a combination

Fresnel and plastic protective covering? I know there are other ways

of checking for coverage besides looking through cut out corners but

since that's the way I've done it for years I'd rather cut the

corners than try to use other methods if cutting the corners is

feasible.

Try putting a light on the ground glass, and then use your dark cloth to look into the lens, and see if you can see all four corners. of your ground glass. I always want at least one corner cut just to let air in and out of the bellows as you open and close it. Too much pressure on the glass, otherwise.

Always has worked for me.

 

www.doncameron.com

To check for vignetting you always check by looking through the lens (set at shooting aperture) from the FRONT of the camera. NEVER from the back.

If you see all corners by looking through the lens from the front you are fine.

Why from the front?

You look through the lens (with filter - lens shade - compendium attached) at the shooting f. stop. It is extremely easy to see the rear of the camera / groundglass - and each corner of the glass. If you can see each corner of the groundglass from the front - where your image is coming from - you will be sure that there is no vignetting. On the other hand if you cannot see each corner you will have vignetting for sure. (Be sure to move your head around while checking each corner by itself!)

 

Actually not my idea - learned it from Ansel years ago...

Looking through the lens is one way, looking through the corners of the ground glass is another. "Open corners offer another advantage, however, in that the photographer can view the lens from the position that will be occupied by the corners of the film to check on vignetting . . . " Stroebel, "View Camera Technique," p. 225. Or "This (referring to vignetting) will be visible in the ground glass (more definitely as the lens is stopped down) OR by sighting from the end of the rail through the lens . . . " (my emphasis) Adams, "The Camera," p. 157. Either way can be used, I'm not aware of any reason to prefer one method over the other. I've always looked through the corners of the ground glass rather than through the lens and I'd like to continue that way if the corners of the viewing screen on the Ebony can be cut. So, back to the original question - does anyone know whether the corners can be cut without damaging the Fresnel/plastic covering?

I asked Robert White if it was possible to cut a 4x5 Ebony fresnel down to 6x9 cm, he said it would crack. Perhaps it is doable with a high-speed cutting disc like a Dremel, but forget a saw or scissors.

 

But Per and others are correct in that it is easier to look from the front through the lens.

Thanks, it doesn't look like it would be easy to cut and based on Robert White's statement I won't try. Given this problem on top of the focusing problems inherent in the Fresnel, I plan to replace it with a BosScreen or Maxwell screen if either is made for the Ebony. With respect to viewing through the back or through the lens, contrary to Per's statement you actually can view through the ground glass as well as through the lens, either way works equally well, it's just a matter of personal preference. My personal preference is to look through the corners of the ground glass. I find it easier to do it that way rather than having to move around to the front of the camera, put my nose up to the lens, and squint through the lens.

Brian,

 

I would think that unless the glass is tempered, and as far as I know it is not.

You might try a sanding wheel to grind down the corners. You can bring the

gg to a glass shop and ask them to carefully grind 1/8" off of each corner.

 

OTOH, obtaining a replacement fro Ebony may be expensive and time

consuming. I would personally look through the lens.

 

Mike

Mike - Ebony's focusing screen consists of a plastic sheet etched on one side and fresnel on the other side. This is covered by a plain glass cover. At least this is true for my SW23.