Glass Bodies a variant-level encyclopedia of vintage lenses and cameras by iwillpat

Mamiya-Sekor Shift C 50mm f/4 (645)

Mamiya · Mamiya 645 · 1985

single source, unconfirmed

Also known as: Mamiya-Sekor Shift C 50mm f/4 · Mamiya Sekor C 50mm f4 Shift · Mamiya 645 50mm f/4 Shift · Mamiya 645 50mm f4 C Shift · Mamiya M645 50mm shift · Sekor Shift C 1:4 f=50mm · マミヤ セコール シフトC 50mm F4 · マミヤ645 50mm シフト

Variants & identification

Variant Mount Years Serial ranges Production
Mamiya-Sekor Shift C 50mm f/4 Mamiya 645 — — —
  1. Element counts, angle of view, aperture range, shift amounts, image circle, closest focus, filter size and dimensions are from Mamiya's Shift C 50mm f/4 instruction manual (scan hosted by IanB Foto) and Mamiya's N-era 645 Interchangeable Lenses instruction sheet (Butkus library).
  2. Weight: the lens's own manual says 705 g; the N-era sheet, Hens and the Wikipedia table say 735 g. The maker's two figures differ and the page shows the sheet's 735 g; Kamerastore's 711 g is a shop's scale.
  3. The family year (1985) is the earliest documented appearance, Mamiya's second-generation 645 Interchangeable Lenses sheet and the lens's own 'M645 Super / M645' manual; it is absent from the 1981 US brochure and present in a later undated M645 manual, so it arrived in the early 1980s. No source gives the year.
  4. Aperture blade count (6) comes only from the Wikipedia lens table; no Mamiya document consulted gives it.
How to tell them apart (expand)
  • The only shift lens of the 645 system: 16 mm of shift with the lens rotated to vertical, 13 mm horizontal, 11 to 12 mm at the diagonal click-stops, over a 97 mm image circle (Mamiya's manual)
  • Manual diaphragm: the lens is focused at f/4 and stopped down by hand, and a metering prism needs the exposure meter connecting ring turned to the stopped-down index (Mamiya's manual)
  • 77 mm filter thread, no hood offered; Mamiya suggests the RB67 sun shield (Mamiya's manual)

Mamiya-Sekor Shift C 50mm f/4:

  • Shift C on the name ring, a shift control knob on the side of the barrel, a shift scale with colour-coded maximum-shift numerals and a shift limit window; the lens rotates 360° with click-stops every 30° (Mamiya's Shift C 50mm f/4 manual)
  • Manual diaphragm with an exposure meter connecting ring and a stopped-down metering index instead of the automatic diaphragm and A/M lever of the other 645 lenses (Mamiya's manual)
  • Mamiya's N-era sheet: 10 elements in 8 groups, 70°, f/32, manual diaphragm, 45 cm, 0.18×, 77 mm filter, no hood, 105.5 mm long, 80 mm diameter, 735 g; the lens's own manual says 705 g

Specifications

Formula
Retrofocus wide-angle with a 97 mm image circle in a shifting, rotating mount, 10 elements in 8 groups (Mamiya's Shift C 50mm f/4 instruction manual; N-era 645 Interchangeable Lenses sheet)
Construction
10 elements / 8 groups
Aperture range
f/4–f/32
Diaphragm blades
6
Min. focus
0.45 m
Dimensions
80 × 105.5 mm
Weight
735 g
Filter
77 mm
Years manufactured
1985
Country
Japan
Coating
Multicoated: the C in Sekor C is Mamiya's multicoating mark (Mamiya's brochures)

What reviewers say

Optical Ratings

Aggregated from the reviews above — follow the links for the full picture.

Vignetting
shift-dependent
Optical formula — Retrofocus wide-angle with a 97 mm image circle in a shifting, rotating mount, 10 elements in 8 groups (Mamiya's Shift C 50mm f/4 instruction manual; N-era 645 Interchangeable Lenses sheet)

History

The Shift C 50mm f/4 is the only perspective-control lens of the Mamiya 645 system, a 31 mm equivalent with a 70° angle of view and an image circle of 97 mm, far more than the 71 mm the 6 by 4.5 frame needs, so that the whole lens can be moved parallel to the film plane. A knob on the side of the barrel shifts it; the lens also rotates through 360° with click-stops every 30°, and the maximum shift changes with the direction: 16 mm with the lens turned to shift vertically, 13 mm horizontally and 11 to 12 mm at the diagonal stops, each indicated by a colour-coded numeral in a shift limit window. It is a ten-element, eight-group design that focuses to 0.45 m, takes 77 mm filters and has no hood; Mamiya’s manual suggests the RB67 sun shield if one is wanted. At 105.5 mm long, 80 mm across and 705 g by its own manual (735 g on Mamiya’s later sheet), it is one of the heaviest 645 lenses.

It is also the one 645 lens without an automatic diaphragm. Focusing is done at f/4 and the aperture ring is then set by hand; a metering prism needs the exposure meter connecting ring turned to the stopped-down index, and Mamiya’s manual recommends f/16 to f/32 when shifted, because light falls off toward the shifted edge, and suggests bracketing by half and full stops until the photographer knows the lens. The manual also describes the two standard tricks of a shift lens: keeping the film plane vertical and shifting up to hold a building’s sides parallel, and shifting sideways to photograph a mirror or window without the camera in it, plus a stitched panorama from two frames shifted 13 mm each way.

There is one version. Mamiya’s second-generation instruction sheet lists it as Shift C 50mm f/4 without an N suffix, and the lens’s own manual is headed M645 Super / M645. It is absent from the 1981 US brochure and present in a later M645 manual, so it arrived in the early 1980s; no source consulted gives the year, and the family year here is the earliest documented appearance. Reviewers today use it mostly on digital backs. Sandeep Murali, on a Leaf Credo 40, finds the unshifted frame sharp edge to edge and stitches a shifted pair into roughly a 24 mm view, but wants more contrast than the 35mm gives; Petri Damstén, on a GFX, finds the corners notably soft at f/4 and worse shifted, and near the native lenses at the f/16 and f/22 it was designed for. Both praise the all-metal build.

When buying, run the shift knob to both limits and back with the lens rotated to several stops, and check that the shift limit window changes colour with the rotation; check that the aperture ring stops down by hand and that the exposure meter connecting ring turns to its click-stop. Mamiya warns against a tripod head whose top extends more than 5 cm in front of the tripod screw, because the shifted barrel can strike it. The RB67 and RZ67 75mm f/3.5 shift lenses are different lenses and are not covered here.

What remains open: the launch year, the end of production, any list price, which of Mamiya’s two weights (705 or 735 g) is right, and the blade count, which only the Wikipedia table gives.

Expand Collapse

This history is AI-written, from the sources listed at the foot of the page. Where the record is silent it says so rather than filling the gap — but no human wrote these sentences.

Example photos

Sample photo wanted — shot with a Mamiya-Sekor Shift C 50mm f/4 (645)? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $360 across 10 fixed-price listings on 2026-09-21 (middle half $350–$380). First day tracked.

Asking prices from the listings scanned, not sales; junk-flagged rows and auction lots excluded; other currencies are not converted.

Show 10 more listings

Buying from Yahoo! Auctions outside Japan. It is a domestic marketplace: sellers ship within Japan, and most will not register an overseas buyer. A proxy service bids on your behalf, receives the item and forwards it, for a fee and a wait. Buyee, Jauce and ZenMarket each accept a Yahoo auction number directly. Listed alphabetically for information — none is recommended over another, and none of these is an affiliate link.

Listings updated 2026-09-21. Links go to the shop or marketplace that carries the item.

Related: Mamiya-Sekor Fisheye ULD C 24mm f/4 (645) · Mamiya-Sekor C 35mm f/3.5 (645) · Mamiya-Sekor C 70mm f/2.8 Leaf Shutter (645) · Mamiya Macro A 120mm f/4 M (645)

Sources (13)

Every page here is assembled from public sources, and the gaps are real ones. If you own this lens, know a serial number I'm missing, or can see where I have it wrong, tell me — corrections, serials and sample photos are all worth having.