I'm not familiar to the Leica R system, but have begun playing with the idea of buying an R Leica lens to adapt to my Nikon just to try the mechanics and optics of Leica lenses. However, I noticed that the Leica site seems to list only current lenses and I would like to compare specs for older lenses also (I'm a bit interested in the 180/3,4 APO). Is there some site that would list the specs of Leica R lenses, past and present? By specs I mostly mean things such as physical dimensions, filter size, appearance of the lens and if possible serial numbers. MTF graphs would be nice too, but I don't expect them to be that easy to find. A bit related to this is how to tell different editions of the lenses apart? It would be easiest if the serial numbers are available for all models, but as a newcomer to the Leica system I find it a bit difficult to be sure in a web auction which version of a particular lens is being sold. Any help is appreciated.