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

Mamiya-Sekor C 45mm f/2.8 (645)

Mamiya · Mamiya 645 · 1975

single source, unconfirmed

Also known as: Mamiya-Sekor C 45mm f/2.8 · Mamiya Sekor C 45mm f2.8 · Mamiya-Sekor C 45mm f/2.8 N · Mamiya-Sekor C 45mm f/2.8 S · Mamiya 645 45mm f/2.8 · Mamiya 645 45mm f2.8 N · Mamiya M645 45mm 2.8 · Sekor C 1:2.8 f=45mm · マミヤ セコールC 45mm F2.8 · マミヤ645 45mm F2.8 · セコールC 45mm F2.8 N

Variants & identification

Variant Mount Years Serial ranges Production
Mamiya-Sekor C 45mm f/2.8 (1975 original, 77 mm filter) Mamiya 645 1975 — —
Mamiya-Sekor C 45mm f/2.8 S (67 mm filter, 0.45 m) Mamiya 645 — — —
Mamiya-Sekor C 45mm f/2.8 N Mamiya 645 1985 — —
  1. Element counts, closest focus, filter size, dimensions and weight for the C lens are from Mamiya's C-era lens brochure (cameramanuals.org); for the N lens from Mamiya's N-era 645 Interchangeable Lenses instruction sheet (Butkus library).
  2. The S lens's figures (0.45 m, 67 mm, 475 g) come from Mamiya's 1981 brochure for the filter size, Japanese Wikipedia for the closest focus and filter, and Philip Hens's 2011 system list for the weight; no Mamiya document consulted gives the S lens's weight or dimensions, so those rest on one source.
  3. Aperture blade count (6) comes only from the Wikipedia lens table; no Mamiya document consulted gives it.
  4. Variant start years are the body generations: C with the M645 (1975), N with the 645 Super (December 1985). The S lens is in the 1981 brochure and no source dates it; the end of C and S production is likewise undocumented.
How to tell them apart (expand)
  • Three versions of one nine-element formula, told apart by the front: 77 mm filter and 0.5 m closest focus on the original C; 67 mm and 0.45 m on the S and the N
  • S or N after the aperture on the name ring; the original has neither. Early S lenses carry a gold S sticker rather than an engraving (Wikipedia)
  • Square slip-on hood on every version, fitted with its sides parallel to the camera body (Mamiya-Sekor C instruction sheet)
  • The front element protrudes and flares in direct light; a hood is recommended (Kikie Wilkins, Emulsive)

Mamiya-Sekor C 45mm f/2.8 (1975 original, 77 mm filter):

  • 77 mm filter thread and a square slip-on hood; the only version of the lens with the 77 mm front (Mamiya's C brochure; Japanese Wikipedia)
  • Mamiya's C-era brochure: 9 elements in 7 groups, 76° angle of view, f/22 minimum, 0.5 m closest focus, 78 mm long, 80 mm diameter, 540 g; the heaviest of the three versions
  • Name ring reads Sekor C with nothing after the aperture and no S sticker or engraving; metal aperture ring

Mamiya-Sekor C 45mm f/2.8 S (67 mm filter, 0.45 m):

  • S after the aperture: a gold S sticker on early examples, engraved on later ones (Wikipedia)
  • 67 mm filter thread in place of 77 mm, closest focus 0.45 m in place of 0.5 m, 475 g in place of 540 g; still 9 elements in 7 groups (1981 brochure; Japanese Wikipedia; Hens)

Mamiya-Sekor C 45mm f/2.8 N:

  • N after the aperture on the name ring; plastic aperture ring (Wikipedia)
  • Mamiya's N-era instruction sheet: 9 elements in 7 groups, 76°, f/22, 45 cm, 0.15× magnification, 67 mm filter, slip-on hood, 70.5 mm long, 75 mm diameter, 475 g

Specifications

Formula
Retrofocus wide-angle with a floating element group, 9 elements in 7 groups (Mamiya-Sekor C instruction sheet; C brochure)
Construction
9 elements / 7 groups
Aperture range
f/2.8–f/22
Diaphragm blades
6
Min. focus
0.5 m
Dimensions
80 × 78 mm
Weight
540 g
Filter
77 mm
Years manufactured
1975
Country
Japan
Coating
Multicoated: the C in Sekor C is Mamiya's multicoating mark; the N lenses carry revised coatings (Wikipedia)

What reviewers say

Optical Ratings

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

Flare & ghosting
hood needed

History

The 45mm f/2.8 was the wide-angle of the Mamiya 645 system at launch, the 28 mm equivalent in Modern Photography’s September 1975 list of seven lenses and the widest of them; the 35mm f/3.5 and the 24mm fisheye came later. It is a nine-element, seven-group retrofocus design with a 76° angle of view, and Mamiya’s Sekor C instruction sheet singles it out, with the 35mm, for a floating system in which some of the elements move as the lens is focused, so that resolution holds to the edges at the closest distances. The original lens is a big one for the format: 77 mm filter thread, 78 mm long, 80 mm across and 540 g, with a square slip-on hood that fits with its sides parallel to the camera body.

The lens went through three barrels on the same glass. The original Sekor C focuses to 0.5 m and takes 77 mm filters. The S version, listed in Mamiya’s 1981 US brochure and marked with a gold S sticker on early examples and an engraving later, brought the closest focus to 0.45 m, the filter thread down to 67 mm and the weight to 475 g; Wikipedia counts the 45 and the 55 as the only two lenses in the line to receive an S version, and no source consulted says when it appeared. The N of 1985, launched with the 645 Super, keeps the S lens’s figures exactly in Mamiya’s N-era instruction sheet (9/7, 45 cm, 67 mm, 70.5 by 75 mm, 475 g) and adds the revised coatings and plastic aperture ring of the N series. Sellers who quote a 45 cm closest focus or a 67 mm filter are therefore describing an S or an N, never the original.

Reviewers treat it as the lens that makes the system: Tim Dobbs on Emulsive calls it probably his best addition, for the field of view and the 45 cm closest focus; Aivaras on 35mmc chose the N over the older lens because samples and reviews say it is sharper with more contrast, and found it feels wider than 28 mm suggests; Kikie Wilkins finds it sharp but notes that the protruding front element flares when a strong light hits it and recommends the hood. No bench test of the manual-focus 45 was found; Popular Photography’s 2002 figures sometimes quoted for it belong to the autofocus 45mm f/2.8 D, a different lens.

When buying, the front tells the version, and a lens without its square hood is a lens that will flare. Check that the A/M lever moves the diaphragm, that the meter coupler on the aperture ring is intact, and that the focusing ring turns smoothly through its whole range, since the floating group moves with it. The 645 AF 45mm f/2.8 D shares the focal length and mount name but is an autofocus lens for the 645AF bodies and is not covered here.

What remains open: the year of the S barrel, the end of C and S production, any list price in yen or dollars, the S lens’s dimensions from a Mamiya document, 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 taken with the Mamiya-Sekor C 45mm f/2.8 (645)
Mamiya-Sekor C 45mm f/2.8 (Gürkan Sengün) — Gürkan Sengün, via Wikimedia Commons (CC BY-SA 3.0)
Sample photo taken with the Mamiya-Sekor C 45mm f/2.8 (645)
Zigzag fence, Ox Hill Battlefield Park: 645 Super, Mamiya-Sekor 45mm f/2.8, Pro 400H (Tom Mills) — Tom Mills, via Wikimedia Commons (CC BY-SA 2.0)
Sample photo taken with the Mamiya-Sekor C 45mm f/2.8 (645)
Open field: 645 Pro, Mamiya-Sekor 45mm f/2.8, Velvia 100 (Tom Mills) — Tom Mills, via Wikimedia Commons (CC BY-SA 2.0)

Sample photo wanted — shot with a Mamiya-Sekor C 45mm f/2.8 (645)? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $350 across 43 fixed-price listings on 2026-09-19 (middle half $310–$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 78 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 2026-09-19. Links go to the shop or marketplace that carries the item.

Related: Mamiya-Sekor C 110mm f/2.8 (645) · Mamiya-Sekor C 150mm f/3.5 (645) · Mamiya-Sekor C 55mm f/2.8 (645) · Mamiya-Sekor C 80mm f/1.9 (645) · Mamiya-Sekor C 80mm f/2.8 (645)

Sources (14)

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.