My very first camera was a Canon AE-1, a film camera with FD lenses. Since I now shoot with a Canon 1D or 6D, the AE-1 and all of the FD lenses I have for it have been collecting a bit of dust. I was up late the other night dreaming about getting a new lens and remembered those FD lenses stashed away in my closet. I tried to fit them on my digital bodies with no dice and realized I probably wasn't the only crazy person to think of this. So I did a search on Amazon for an adapter. I found one that said it worked with the 1D. I ordered the adapter and while waiting for it to arrive, I spent some time on Google and watched a bunch of videos online about people who have done this before, including this guy who removed the glass from the adapter which caused the lens to work like a macro.
The adapter arrived and I immediately tried it. Unfortunately, I could not get it to work on the 1D. The camera would attempt to fire, but would result in an error which indicated a bad connection with the body and the lens. I was successful in getting it to work on my old Rebel XT and the 6D. On my FD lens you set the aperture on the lens, the body was reading 00 in place of the aperture. I also had to manually focus. It took me a bit to figure out how to accurately expose the image. It was difficult in low light situations, but got easier when I moved outside and had more light to work with.
The images have a slight haze and almost a vintage quality to them. The interesting thing about this is that older lens for film cameras are incredibly inexpensive since they are outdated. The newer equivalents will run thousands of dollars, while you can get FD lenses for less than $25.
This is definitely not something that can replace modern lenses for client work in portraits or weddings because I feel, due to the adapter, I have less control over the image and the effect it provides is something that I can add in Photoshop with far more control. However, it is incredibly fun for personal projects and I plan to do some fun work with it coming up.