I was thinking of my drawer full of Leica bits and pieces that have been accumulated over the years purely to make LTM's work. And having grown up (a long time ago actually),I realised I'm not one of the people who relish talking about part numbers and barn door's and slip on this or that's. If I use 39mm filters with my other lenses it makes sense to unify the kit and carry less around. For me the photograph isn't so much about demonstrating a particular lens, it is about the subject of the photograph and if a big black lens on the day is more efficient than a 5cm Elmar I'm not going to beat myself up about it. That said, I would have to go out and buy a Canon or a Nikon to make it happen.