I have been using both m42 and Nikon manual focus lenses on my 4/3 camera, with of course, the appropriate adapters. That system has the disadvantage of a relatively small sensor but boy is it flexible in terms of the range of lenses it will accept. My only slight disappointment is that it does not appear to be possible to get Canon FL mount lens adpaters for the 4/3 system (the register distance is pretty similar leaving no room, I surmise, for the adapter to be of sufficient thickness to bear the weight of the lens.) Its a lotta fun using manual focus lenses on digital cameras. I have recently been casting covetous eyes on Contax and Leica R lenses - both of which have the necessary adapters. I will eventually succumb.