Mamiya Mamiya-Sekor C 150mm f/3.8 N/L

Flash sync at every shutter speed up to 1/500 is what you are buying here, full stop. Mamiya built the 645 system in the mid-1970s as a cheaper, lighter route into medium format than a Hasselblad, and the lens lineup grew up around studio and wedding shooters who needed reach for heads-and-shoulders work. The 150mm was that reach. On the 6x4.5 frame it sits roughly where a 90mm to 100mm lands on 35mm, the classic portrait distance: close enough to flatter a face without the photographer crowding the subject. The N/L tag marks the leaf-shutter generation, and the "L" tells you the shutter itself lives in the lens barrel rather than the body. The aperture was always in the lens; only the shutter moved.

That leaf shutter is the reason a studio portraitist pays for this version instead of the standard 150. You can shoot near wide open in bright daylight with fill flash and never hit the sync ceiling that a focal-plane body slams you into at 1/60 or 1/125. If you meter that kind of work in Zone Light Meter, the leaf shutter is why your flash key reading stays honest all the way up the speed scale instead of stalling out partway.

Optically it does what a well-corrected short tele of its era does. Wide open at f/3.8 it has a softer, gentler character with mild falloff, the sort of rendering people reading skin tones tend to like, and it tightens up noticeably stopped down a stop or two. Most users describe the out-of-focus rendering as calm and free of obvious busyness, and the color as easy to grade on negative film. Take those as the usual impressions rather than lab-measured verdicts; this lens was never benchmarked to death the way modern glass is, and copy variation is real on bodies this old.

The honest weakness is speed and bulk against what you get back. At f/3.8 it is not a low-light lens, and the leaf-shutter barrel is a chunky thing to hang off the front of an already heavy body. Focusing wide open in dim church light works, but the finder dims and the thin depth of field at portrait distance is unforgiving of a missed eye. Treat it as daylight and flash glass, not an available-darkness lens.

Today it lives at the bargain end of medium-format portrait glass. People cross-shop it against the standard focal-plane 150mm f/3.5, which is lighter and cheaper, and the call comes down to one question: do you need the leaf shutter's flash sync? If yes, this is the obvious answer, and it stays cheap because the 645 system never carried Hasselblad's collector premium. The lens takes a 67mm front thread, so check the other glass in your bag before assuming one filter set covers everything; sizes vary across the LS line. For film shooters lighting portraits in the 2020s, the price-to-result math here is hard to argue with.