Lenses don't make rectangular images. They make circular images. Lenses on 35mm and medium format cameras make an image circle just large enough to cover the film. It's quite a bit different in large format. With a large format view camera it's important to not ony cover the film but to have extra for lens and back movements. And large format cameras come in a variety of sizes. I've been collecting a variety of lenses, mostly process lenses, and had a general idea of what the lens coverage was but wanted to see it for myself, so to speak. So I cut up some cardboard and taped it together (with a few iterations) to make Gordy's Grand Image Circle Measuring DeviceŽ.

The base is a Black and Decker work bench. The bellows/dark cloth is nylon pack cloth. My old dark cloth really wasn't that dark so I went to Island Fabrics in Freeland and asked for an opaque black cloth. The nylon pack cloth was a little over $10 for a yard of 60 inch wide material. I will try it as a dark cloth for the Burke & James. I like it. No light gets through. It's a little stiff which is nice. And it's waterproof!

The Black and Decker work bench is a marvelous device. The front part of the bench can be located in three positions and the aft part is moved by screws turned by two handles.

I used waxed paper to focus on. The image size is 16" x 8 1/2". The size was determined by a box I had handy and the width of the wax paper. I focus with the two orange handles. Just turn them around and the back moves back and forward. The dark cloth covered three sides and I stuffed some garbage bags in the bottom to cut the light. My lenses were mostly light process lenses and this worked fine. It's a bit wobbly but served it's purpose. I didn't put on my two heavy lenses (10" Elgeet and 21 1/4" Kodak) since they would have probably collapsed the front standard.

Some day I may make a more sturdy plywood version. I think there are some interesting possibilties for making a real camera out of one of these work benches. A cheap ultra large format either lensed or with a pinhole. Could be interesting. And cheap.

So what did I find out? Well, there was good news and not so good news.

Both my 127mm Kodak Ektar and 90mm Wollensak don't quite cover 4x5. Bummer. But they do cover 3.25x4.25 which is the size of my Speed Graphic where the 90mm was going to end up eventually.

I built a temporary cardboard lens board for the Speed Graphic and it works fine. I thought it might see the bed but it doesn't seem to so I won't have to drop it. I will need to make a scale on the bed for the 90mm so I can scale focus it. The 127mm and 90mm are equivalent to 42mm and 30mm on the Speed Graphic.

My 150mm Graphic Kowa, 210mm Schneider G-Claron leave lots of movement on the 5x7. The 330mm actually covers more that the 18". The 18" was all that my back showed. The 10" Elgeet is probably between the 210mm and 330mm lenses in coverage. The 21 1/4" Kodak would probably cover the side of a house.