I am considering the purchase of an APO Telyt M 135mm f/3.4 lens for use on my M10 camera. At present, I am NOT planning to buy this lens. I own three Leica lenses: the Summicron 35mm and 75mm, and the Summilux 50mm. My questions are for those of you who own a 135mm lens (any type) that you mount on an M camera body: 1) How often do you use this lens? 2) Primarily for what purposes? 3) Do you find that a Visoflex 020 (or other) EVF is highly advisable for focusing? I own Nikon DSLRs (D500 and D800) with telephoto zoom lenses, which if used, would include the range afforded by the 135mm prime lens. I will be taking two vacation trips this summer, and I want to travel light. I may not even take all my Leica lenses. But the 135mm APO Telyt is in my mind as a possibility, in lieu of taking any DSLR and zoom lens. Even if I were to bring all my Leica lenses, all but one or two of them would likely stay behind in a hotel or ship or car. I would make do with whatever I have on my person at the time. I would have no time to concentrate on taking pictures if I found myself doing lots of lens swapping from a carried bag or daypack. Here’s my own view of the 135mm prime lens: I am dubious on how often I would need 135, as compared to using the 75 (or even the 50) and cropping if needed. Once one needs a longer focal length than 75 or 90, it’s most likely that a DSLR with a long telephoto zoom or prime lens is going to be needed, instead of 135mm. I also have questions regarding my ability to focus the 135mm lens on an M10.