Olympus Zuiko Auto-S 50mm f/1.2

Wide open at f/1.2 this lens does not snap to focus, it glows. There is a soft veil of spherical aberration over everything below f/2, a low-contrast bloom that wraps highlights in light and turns a streetlamp into a halo. People either love that or they shoot it stopped down. By f/2.8 the veiling clears and by f/4 the lens is genuinely sharp across the frame, so what you are buying is two different lenses depending on where the aperture ring sits.

It is a double-Gauss, the standard fast-fifty layout, and it was the fastest of the OM 50mm primes when Olympus shipped it in the early 1980s. Not the only f/1.2 normal in the system though; there was an earlier G.Zuiko 55mm f/1.2 at the same speed. The whole point of the OM system was small bodies and small glass, and this is the one place Olympus broke that promise. The f/1.2 is a big chunk of metal and glass next to the dainty f/1.8 that came on most OM-1 bodies. It uses the 49mm filter thread, the most common Olympus size and one it shares with many of the other Zuiko primes, which is a real convenience if you already own OM glass and a set of filters.

The rendering fingerprint people chase is the falloff. Focus drops away fast at f/1.2, and the out-of-focus region behind the subject stays soft, with round, well-corrected highlight discs near center that turn slightly cat-eyed toward the edges. It is a portrait lens first. Shooters use it for available-light faces, indoor environmental portraits, and that dreamy half-stop-open look where the eyes land sharp and everything an inch behind them has already dissolved. Color is neutral, maybe a touch warm, and contrast is moderate even stopped down, which suits skin.

The honest weakness is flare and that same wide-open softness when you do not want it. Point it at a bright source with no hood and contrast collapses; the multicoating is good for its era but this is an old optical formula and it shows. Field curvature also means the corners and the center do not always agree on the plane of focus until you stop down. If you need clinical sharpness at maximum aperture, this is the wrong tool. The earlier f/1.4 Zuiko is actually crisper wide open and runs roughly a quarter to a third of the price.

Today this sits in the collectible-fast-fifty bracket, well below the Canon FD 50mm f/1.2 L or the Leica options but above ordinary nifty-fifties. People cross-shop it against the Nikkor 50mm f/1.2 AI-S and the Canon FD f/1.2, and the Olympus usually wins on size and price while giving up a little build heft. The reason to own one is the glow, and the formula that produces it is genuinely hard to fake with a corrected modern design.

One metering note. When you work it wide open in dim rooms, meter for the shadows you care about and let the highlights bloom; the lens is already lifting them for you. In Zone Light Meter, place your skin tone on the zone you want and read in the actual low light you are shooting. The f/1.2 setting buys you about a stop and a half over an f/2 fifty, a bit over a stop versus the common f/1.8, and that gathered light is exactly where this lens earns its keep.