Olympus Zuiko Auto-W 24mm f/2.8

Wide open at f/2.8 this lens vignettes hard and goes soft at the edges, then snaps into a different lens entirely by f/5.6. Center sharpness is already there at f/2.8, but the corners stay mushy until you stop down to f/8, where the frame finally pulls tight from edge to edge. Olympus built eight elements in seven groups into a retrofocus wide that is barely bigger than a 50mm pancake, and that compactness is the first thing anyone notices when they pick one up.

The distortion is the honest catch. It is not simple barrel that you can dial out with a slider. There is a moustache wave to it, the kind that bows out near the center of a horizon line and curls back at the corners, and on architecture or a hard sea horizon you will see it. For environmental portraits, street, and reportage, where nothing in the frame is a dead-straight reference line, it disappears completely.

Color is the Zuiko signature people talk about: saturated without going garish, with the slightly cool, snappy contrast that runs through the whole OM lens line. Flare resistance is one of those traits that varies from sample to sample and coating to coating, so shooting into a low sun will throw some veiling haze and a little chromatic fringing at the aperture extremes, both of which clean up by f/8. The out-of-focus rendering is not swirly, but it is not especially creamy either. Backgrounds can pick up some structure, and the highlights take on cat-eye shapes toward the corners wide open. Either way, a 24mm at f/2.8 is about depth, not subject isolation, so it rarely matters for the work this lens does.

Who reaches for it: documentary and travel shooters who want one small fast wide that lives on an OM-1 or OM-2 body without unbalancing it, plus a large adapted following on mirrorless full frame, where the 49mm filter thread and pocketable barrel make it an easy carry. People cross-shop it against the Nikkor 24mm f/2.8 AI-S and the contemporary Canon FD 24mm. All three are compact primes in the same affordable-classic price bracket, so the size edge that really matters is against the bigger, faster wides. Cross-shoppers argue endlessly about which one holds the corners better, with results that depend on the sample and how far you stop down. Fans tend to prefer the Zuiko rendering, and the small barrel and 49mm thread make it the easy carry of the three.

The practical note for shooting it: at f/2.8 the corner falloff is real, so when you meter a backlit or evenly bright scene and want those edges to hold detail, bias your exposure for the corners rather than the bright center, or just stop down a stop. Zone Light Meter will place your shadows where you want them, but the lens decides how much light actually reaches the film edge, and at maximum aperture that is noticeably less than at the middle. That 49mm thread also takes cheap, common filters, which makes it a friendly mount for a graduated ND when you are working bright skies and want to tame that vignette-prone top corner on purpose.