For the last few years I've been using a modified EM for just such purposes (plus, I'm cheap). You can buy them for peanuts, and they're tiny and light. Just bend the metering arm that rotates around the outside of the lens mount up a little, and bend the stop down arm inside the lens mount out of the way (the one on the left that closes the aperture on AI lenses when you fire the shutter). A fun little test camera that works in the camera's AE mode in stop down metering w/ non AI lenses. So far I've used it w/ an H 50 2, a Q 135 3.5, and a Leica R 90 Elmarit w/ an adapter/lens mount. They all worked fine. Cost for the camera was $20 including shipping, so before I get flamed for "butchering" a fine old EM, we're talking $20 here, and it do work a treat.
