Mamiya Mamiya-Sekor Z 110mm f/2.8 W

Shoot a head-and-shoulders portrait on this lens wide open and the plane of focus sits razor thin across the eyes while everything behind it melts into a smooth, undistracting wash. That is the RZ67 110mm signature. It is the standard lens for the system, roughly a 55mm equivalent once you account for the 6x7 frame, so it sees about the way your eye does, but the out-of-focus rendering is pure medium format. Big negative, gentle falloff, no nervous edges in the blur.

Wide open at f/2.8 it is sharp where you put the focus and forgiving everywhere else, which is exactly what you want for skin. Stop down to f/5.6 or f/8 and it snaps to clinical resolution corner to corner, the aperture range most studio shooters live in. Contrast is moderate rather than punchy, the kind of tonal curve that holds a wedding dress and a dark tux in the same frame without blowing either out. Color is neutral and honest. It does not editorialize the way some German glass does.

This is the lens that built a thousand commercial portrait sessions. The RZ67 owned the studio in the 1990s for catalog, fashion, and beauty work, and the 110mm was the body cap that came on the camera and never came off. The leaf shutter is a big part of why. It is built into the lens, an electronic Seiko unit, and it syncs with strobe at every speed up to 1/400. No focal-plane sync ceiling, so you can drag the shutter or kill ambient with flash at any setting. Portrait and product shooters cross-shop it against the Hasselblad 80mm Planar, and plenty chose the Mamiya for the bigger frame and the cheaper entry into the system.

The honest weakness is the whole package, not the optic. The RZ67 body is a brick, the lens is heavy 77mm-threaded glass, and the shutter is electronically timed. Run the battery flat and you drop to the single mechanical emergency speed of 1/400 second, enough for a flash frame or bright daylight, but you lose every other speed until you swap the cell. Nobody hauls this up a mountain. It is a tripod-and-studio tool, and handheld below 1/125 you will feel every gram.

For metering, lean on that leaf shutter. Because it syncs flash across the full speed range down to slow settings, you have real control over the ambient-to-flash ratio, and Zone Light Meter handles both halves: meter the strobe with the app's incident or spot reading, then set your slow shutter speed to place the background exactly where you want it on the zone scale.

Used prices stay reasonable because the system is heavy and the digital crowd moved on, which makes this one of the cheapest ways into genuinely beautiful medium-format portraiture. The glass was never the problem with the RZ67. It was always the back-ache. If you can live with the weight, the 110mm f/2.8 W still out-renders most of what people pay triple for.