I bought a stripped down 1920's (?) era speed graphic with the intent of playing with making some lenses. After about 2 years, I finally got around to doing a simple concave-concave lens. It is about an f3-ish lens with no stops. I am not all that happy with the result. Honestly, it was almost impossible to focus. It was incredibly bright though!It looks like it needs to be stopped down a little (f5 maybe) to sharpen up the center. I'd like to see some sharpness in the center 50% or so of the frame. I may try a landscape design next (2 convex-conves-convex lenses with a central aperture. I tried this with an 8x10 and it worked well. An 8x10 is a bit unwieldy and expensive to experiment with, though!
Any suggestions would be welcome!