You asked
Best telephoto lens for the leica m9?
For telephoto on the Leica M9, the longest reach in the catalogue is the Leica APO-Telyt-M 135mm f/3.4. It's the one I'd pick for distant subjects and tight portraits, and it's a good match for the M9's full-frame sensor.
For something more everyday, the Leica APO-Summicron-M 90mm f/2 ASPH is a sharp, fast short telephoto that's easy to carry and handles portraits well. If you want a budget option, the TTArtisan M 100mm f/2.8 Bubble Bokeh gives you a bit more reach for less money, though its character is more playful.
The M9 has no in-body stabilisation, so keep your shutter speed up when shooting at 135mm. The lenses guide has more on how focal lengths translate to subjects.
Written by Claude from this site's pages.