My Grandfather worked at a camera store for 40 years. During that time he collected quite a few Leica R lenses (and tons of other camera equipment). I am lucky enough to have use of his Leica (Leitz Wetzlar) lenses. I think the biggest advantage of lenses like this is the handling. There is no substitution for vintage manual focus glass when it comes to smooth focus action and long focus throws (except the new Zeiss ZE and ZF or cine lenses). I have posted a series of photos taken at the same settings (F2.8 ISO 100 at 1/80th) with a T2i.
35mm F2 Summicron R
50mm F2 Summicron R
60mm F2.8 Elmarit Macro
90mm F2.8 Elmarit R
135 F2.8 Elmarit R
180mm F2.8 Elmarit R
Lens Test Shots (all at ISO 100 f2.8 except the 17-40 at ISO 200 F4)
180mm F2.8 Elmarit R
135 F2.8 Elmarit R
90mm F2.8 Elmarit R
60mm F2.8 Elmarit Macro
50mm F2 Summicron R
35mm F2 Summicron R
17-40 F4L at 40 (ISO200 F4)
17-40 F4L at 17 (ISO200 F4)
11-16 at 16
11-16 at 11
35mm F2 Summicron R
50mm F2 Summicron R
60mm F2.8 Elmarit Macro
90mm F2.8 Elmarit R
135 F2.8 Elmarit R
180mm F2.8 Elmarit R
Lens Test Shots (all at ISO 100 f2.8 except the 17-40 at ISO 200 F4)
180mm F2.8 Elmarit R
135 F2.8 Elmarit R
90mm F2.8 Elmarit R
60mm F2.8 Elmarit Macro
50mm F2 Summicron R
35mm F2 Summicron R
17-40 F4L at 40 (ISO200 F4)
17-40 F4L at 17 (ISO200 F4)
11-16 at 16
11-16 at 11