You asked
What cameras fit the leica apo summicron m 75mm f 2 asph?
The Leica APO-Summicron-M 75mm f/2 ASPH is a manual-focus prime for full frame, and it fits the Leica M mount. The site lists it with a long run of M bodies, so you have plenty of choice. If you want the newest, the Leica M11 and Leica M11 Monochrom are the ones I'd look at first. For a body that's a little more affordable, the Leica M10 is a solid all-rounder, and the Leica M10-D gives you a screen-free shooting experience if that appeals. Since 75mm is a portrait focal length, any of these will do the job; the choice really comes down to budget and whether you want colour or black and white.
The full list also includes the M9, M (Typ 240), M-E, M-P and M EV1, all on the Leica M mount page. If you're buying used, the buying used guide explains what to check.
Written by Claude from this site's pages.