When I got back into film photography, one of the first lenses I picked up was a used 135mm f2.8 AIS Nikkor with retractable lens hood. I fell in love with a moderate telephoto for landscape photography. Most of my 35mm shots have been captured with either 24mm, 85mm, or 135mm lenses. When I got my first Leica, the Leica M-A, I wanted something that would be between the 85mm and 135mm focal lengths. While Leica does have a 135mm offering, I am put off by rangefinder accuracy degradation at longer focal lengths. So I decided on a used Leica 90, the F/2.8 Elmarit-M to be precise.
A few key drivers in selecting the Elmarit-M is the combination of modern Leica optical design and the sliding lens hood. I wanted a Leica rangefinder for travel and backpacking to supplement my medium format gear. You can not underestimate a sliding lens hood when rationing space in a photo backpack. This 90mm with the M-A gives me a go to telephoto in a compact package.
Now this is Leica glass, so as one would expect, the optical performance is top notch. If you get one, do run it through it's paces with some test shots. Make sure there isn't sample variation or issues due to abuse. But other than these small concerns with buying any gear used, you will be getting a top shelf medium telephoto.
Non that I can see. The 90mm frame lines are a bit small in the viewfinder so I opted to pair the Elmarit-M with the Leica 1.4x magnifying eyepiece. This is a very well made finder that fills your view with the 90's frame lines. Besides making shots easier to compose, you will see the rangefinder patch better, improving focus accuracy.
I've always thought Leica lens reviews that talk about optical performance are inherently flawed in concept. 99% of lenses made by the 'red dot' are top performers. The real question is if the size, weight, and ergonomics matches your shooting preferences. Having a 90mm on a precision 35mm camera, and weighing in at only 1098 grams is huge when compared to my Nikon F6 and 85mm 1.8D combo tipping the scales at 1457 grams. In addition, the space consumption in a bag is much less with the Leica setup. Which camera I bring will be decided by weather conditions and if I need to use a polarizing filter, as the Nikon F6 would handle harsher conditions better.