That is a thin tele Elmarit. Mine is fine and started life as the Leica rep`s sample. 2.8 is a little soft, 4 and smaller are sharp. Like many 90`s, it goes a little soft under 6 feet, but stopping down helps on this lens although not all 90`s benefit from stopping down up close.
They are a little flare prone, so use a shade, the 90/135 clip on is best or the furnished rubber one.
Some have developed separation in the rear elements and it is uneconomical to repair. I think if it is ok now, it should remain that way. No guarantee.
I replaced mine with the new 90 4.0 macro which makes this one look outclassed shall I say, although it is typical of lenses of the era. Mine is still in my inventory.
Without a shade, it is a little longer than a 50 so it is small. 39mm filters or ser. 5 1/2 inside the rubber shade. Guess what I use.
