Minolta MD Rokkor 50mm f/1.7

This is the lens that I originally received with my SR-T 101. A simple "nifty fifty", with a very cromulent widest aperture of f/1.7. It's a compact, and very nice to use all-rounder lens that stays on my camera most of the time. While it gets a bit too soft for my liking at wide open (like most vintage lenses from this era), stepping down to f/2.8 already gives very good results, and that extra bit of speed can come in handy in darker situations and makes the viewfinder nice and bright.
There are faster 50mm lenses for this mount, all with their own particular trade-offs but 50mm being my favorite focal length I'll definitely try to get my hand on an f/1.4 or even an f/1.2, even if they are not better in every aspect.