I am using a field camera with a 6x7 roll film back. I'm looking for a low-quality lens that will fit on a lens board, but with an image circle that just barely covers the format, and a circle of sharpness that falls off greatly at the corners.....maybe an old barrel lens of some sort? Any suggestions? I realize could accomplish this with Tilts and swings, but I'm looking for something different. If I have to make a special lens board, or even the lens itself for that matter, I would not be afraid to. I'm not trying to get somebody to sell me a lens here, I'm just looking for some suggestions.