Quick question. I came across a brass Darlot projection lens while at an antique store today. When I got it home and popped it on my camera to check the focal length, I could not get anything to focus. I disassembled the lens and found that it was missing one of the elements in the rear group. D’oh!

I popped the cemented doublet on the camera and noticed that I could kind of achieve focus with it by itself. Will this group be usable as a soft focus kind of thing? If so, how can I get a rough idea of the speed of it? Or should I just consider it an investment in a pretty paperweight?

Thanks for any help!