Mamiya-Sekor Fisheye C 37mm f/4.5 (RB67)

The 37mm f/4.5 is the Mamiya RB67’s fisheye, a diagonal design that puts 180 degrees across the corners of the 6 × 7 frame, which Mamiya’s c. 1994 brochure calls the equivalent of 18 mm on 35 mm film. It belongs to the Sekor C generation and is the first lens on the cover of Mamiya’s Interchangeable Lenses for Mamiya RB67 booklet, which gives 9 elements in 6 groups, a picture angle of 180 degrees, minimum aperture f/32, no hood, and 1,370 g, and prints its cross-section on the second page. The booklet says the specific instructions for the fisheye travel with the lens, as they do for the 140 macro, the 150 soft focus and the 500. Japanese Wikipedia, citing Mamiya’s catalogue, puts closest focus at 0.257 m, which is 0.0064 m from the front rim, near enough that the rim itself can touch the subject. Its filters go at the back: 40.5 mm screw-in, four of them supplied according to Japanese Wikipedia, since a fixed petal hood and a bulbous front element leave no thread at the front.

There is only the one version, so telling versions apart is not a problem the buyer has. No 1970 single-coated fisheye is recorded, camera-wiki’s lens table and Japanese Wikipedia’s K/L list both have no 37, and Mamiya’s c. 1994 brochure still lists the Fish-Eye C 37mm f/4.5 in the RB67 Pro SD system alongside the K/L lenses, so the C lens was sold unchanged into the 1990s and served all three bodies. On the Pro-SD’s wider 61 mm mount it takes the same 7 mm lens mount adapter ring Mamiya recommends for every Sekor C; on the Pro and Pro-S it mounts directly. Its introduction year is nowhere stated in the sources consulted, so the 1974 in the table is the start of the C generation and no more than a floor. The weight is the one figure the sources fight over: Mamiya’s booklet says 1,370 g, while Kamerastore, The Fish List and the RB67 Camera Guide all say 1,240 g, and only the maker’s figure is carried here.

The reviewers this catalogue indexes have used it more as a tool than as a subject. Jeremy Mudd on Emulsive runs it on a Pro SD with 35mm film loaded in a 220 back, which yields a 24 × 72 mm strip, and then corrects the fisheye curvature in post; he notes quite a bit of distortion at the edges, especially when the lens cannot be held perfectly level, and comes back to the setup for the 1:3 aspect ratio rather than for the fisheye look. Nothing on 35mmc, Kosmo Foto, analog.cafe, Shoot It With Film, Japan Camera Hunter or the KEH blog was found that names the lens and says anything about it. The Photrio thread that calls it a fun lens, and the lens-db entry, could not be read from here. Casual Photophile, Ken Rockwell and Lomography are not consulted by this catalogue.

Buying is about the shutter and the glass, in that order. The Seiko #1 lives in the lens, is cocked by the body, and after years in a bag will often hang at T or drag at the slow speeds; before mounting, the cocking pins on the barrel must be turned all the way to the red marks, and the booklet says a lens left unused for a long time should be stored with the shutter released. The front element has no filter to protect it and cannot be capped by anything but its own deep cap, so look for cleaning marks and chips on the dome. Check that the rear filters are present, because the lens is designed to have one in the light path, and that the mount adapter ring is there if the lens is going on a Pro-SD. The Pro-S manual and Mamiya’s own accessory page exclude the 37 from the Bellows Lens Hood G-3. No launch price in yen or dollars was found, no serial-number table exists, and no dimensions come from Mamiya’s own documents.