This is from my blog entry: http://oldlenses.blogspot.com/2011/02/making-useless-lenses-useful.html

Sometimes we have no idea why we buy certain things. An impulse? An idea that flashed in our heads that one day it might be useful? Or, just because we want it? No matter, we would later look at these stuff and wonder what the heck we were thinking! Instead of throwing them out, we need to turn them into something more useful than paper weight to justify our original purchases.

I have a few 8mm movie zoom lenses that fit this scenario. They can not be used on anything other than 8mm movie cameras, but it would be so nice to make them serve some photographic purpose again. Using them as a full lens is out of the question, so why not use part of them? The rear of the lens is too small to be useful, but the front element is large and can form images.

To play with this lenses, you really will need a focusing helicoid, either buy one or make your own, or use a macro bellows. There won't be aperture settings, unless you plant them into an existing lens barrel that already have apertures. Using only the front element usually means the lenses are not optically corrected, as they would be when combined with the other elements in the original lens. This actually turns out to be even more fun than just using them as designed, because, they act like soft focus lenses! The un-coated lenses are even better than the coated ones for this purpose.

The good news about making this kind of lenses is that they don't have to fit exactly. No worries about decentering elements, perfect focusing, etc. It's the effects that we are after. So, use whatever that you can to make it mount on your camera, even holding it with your hands!

I certainly had fun trying them out. It made me feel better that after many years of sitting around, digital cameras have made them into something useful and interesting.