You asked

What is the leica summilux m 21mm f 1 4 asph good for?

The Leica Summilux-M 21mm f/1.4 ASPH is a wide, fast, manual-focus prime for full-frame Leica M cameras. Its f/1.4 maximum aperture helps in low light and gives you a shallow depth of field when you want it.

It frames wider than the rangefinder's frame lines, so you'll need an external finder, live view or an EVF to compose accurately. If you're after wide scenes, landscape covers how to use a wide view.

It fits a long list of bodies. Good everyday choices are the Leica M11, the Leica M10, or the Leica M (Typ 240) if you want to save money. Full details are on the lens page.

Written by Claude from this site's pages.

From these pages