Is the leica super apo summicron sl 21mm f 2 asph good for street photography?

It can work for street, but I wouldn't buy it for that alone. The Leica Super-APO-Summicron-SL 21mm f/2 ASPH is a fixed 21mm with autofocus and no stabilisation. The page doesn't give its size or weight, so I can't vouch for how discreet it is.

Street work rewards gear you barely notice, as the Street guide says. The lens fits the Leica CL, an APS-C body. On that sensor it frames like 32mm on full frame, a handy everyday street view that's easier to carry. The sensor guide makes the same point: for street, a good APS-C camera is usually enough.

Written by Claude from this site's pages.