Minolta AF 50mm f/1.7

Dim reception hall, the band starts, people are dancing and you have one second to grab the shot before the moment is gone. Snap a Maxxum 9000 or a 7000 up to your eye with this 50mm on the front and the lens racks to focus before you have finished thinking about it. A manual-focus fifty in that same room makes you hunt the split-prism in the dark and miss it. This one finds the face and locks. It shipped as the standard prime for the camera system that made autofocus actually work in 1985, the Minolta Maxxum line (Dynax in Europe, Alpha in Japan), the first integrated-AF SLR system that sold in serious numbers.

Optically it is a double-Gauss of six elements in five groups, the proven layout for a fast normal, and it behaves like a good example of one. Wide open at f/1.7 it is soft with a faint glow and some vignetting in the corners, perfectly usable for a portrait but not where the lens does its best work. Stop to f/2.8 and the center snaps into focus hard; by f/4 the middle of the frame is excellent. The edges lag, though. They only firm up around f/5.6 and do not really peak until f/8, where you finally get sharpness clean across the frame. Contrast is high and the color is neutral and modern, a little cooler than the warm vintage Minolta MD glass that came before the A-mount switch.

Bokeh is better than the price suggests. Wide open the out-of-focus rendering is generally smooth and the highlight discs stay round, pleasant for the class. The honest quirk is the aperture itself: seven straight blades, not rounded ones, so the moment you stop down past f/1.7 those background highlights turn into little heptagons. Keep it wide if you want round circles. If you want creamy separation across the whole range you reach for the 50mm f/1.4 sibling, which is the lens people cross-shop this against and the one that costs more than twice as much on the used shelf for half a stop and smoother rendering stopped down. For most work the f/1.7 is the smarter buy.

That used shelf is the whole appeal now. These trade for almost nothing because Minolta and Sony made a flood of them across fifteen years, and every one of them mounts straight onto a Sony Alpha A-mount DSLR with autofocus intact, or adapts onto Sony E-mount mirrorless. Sony inherited the A-mount when it bought Konica Minolta's camera business in 2006, so a lens built for film bodies still autofocuses on current digital ones. Buy one as a first fast fifty and you have spent the price of a couple of rolls of film.

Practical note for film shooters: at f/1.7 in a dark venue you are metering at the edge of what the scene gives you, so meter for the shadows you actually care about and let the highlights fall. Zone Light Meter reads off the wide-open aperture, so dial in f/1.7 and place your subject's skin on the zone you want rather than trusting an averaged reading that the dance-floor spotlights will wreck. The 49mm front takes common, cheap filters if you want a polarizer or a warming filter for daylight color work.