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

Mamiya-Sekor 90mm f/3.8 (RB67)

Mamiya · Mamiya RB67 · 1970

single source, unconfirmed

Also known as: Mamiya RB67 90mm f/3.8 · Mamiya RB67 90mm f3.8 · Mamiya-Sekor 90mm f/3.8 · Mamiya-Sekor C 90mm f/3.8 · Mamiya Sekor C 90mm f3.8 RB67 · Sekor C 90/3.8 · マミヤ RB67 90mm · セコールC 90mm F3.8

Variants & identification

Variant Mount Years Serial ranges Production
Mamiya-Sekor 90mm f/3.8 (1970, single-coated) · Seiko #1, T and 1s–1/400, M-X sync Mamiya RB67 1970–1974 — —
Mamiya-Sekor C 90mm f/3.8 (1974, multicoated, 7/5 recomputation) · 7 elements in 5 groups (Interchangeable Lenses for Mamiya RB67 booklet; Pro-S manual) · Seiko #1, T and 1s–1/400, M-X sync Mamiya RB67 1974–1990 — —
  1. Element and group counts, picture angles, minimum apertures, hoods and weights are from Mamiya's own lens booklets and the RB67 Professional and Pro-S manuals as hosted by butkus.org. Closest-focus figures (from the front rim) are from Japanese Wikipedia, which cites Mamiya catalogue R790503.
  2. The RB67 Pro-SD's 90 is the Mamiya K/L 90mm f/3.5 L of 1990: 8 elements in 7 groups with ultra-low-dispersion glass and a floating element, closest focus 448 mm, 960 g (Mamiya Pro SD lens page; Japanese Wikipedia; camera-wiki). It is a different maximum aperture and so, by the site's one-aperture rule, a different family; it is not on this page.
  3. The Sekor NB (new barrel) 65, 90 and 127 are listed only by Japanese Wikipedia, which says the barrel was redesigned and gives no date. Carried as a single-source claim.
  4. Generation start years are those of the bodies the lenses launched with (Professional 1970, Pro-S 1974). No source gives a month for the 90's own changeover, and no discontinuation dates are published.
How to tell them apart (expand)
  • Two name rings for the f/3.8: Mamiya-Sekor (1970, single-coated, chrome ring early) and Mamiya-Sekor C (1974, multicoated). A ring reading K/L 90mm f/3.5 L is the Pro-SD lens and a different family
  • Weight sorts the two: 705 g for the Sekor, 805 g for the Sekor C; both take 77 mm filters and the screw-in hood shared with the 127, 180 and 250, folded back halfway for the 90
  • On the Pro-SD's 61 mm mount both versions want the 7 mm adapter ring Mamiya recommends for light sealing; on the Pro and Pro-S they mount directly
  • Every version carries a Seiko #1 leaf shutter cocked by the body's lever, with cocking pins on the barrel that must be turned fully to the red mark before mounting

Mamiya-Sekor 90mm f/3.8 (1970, single-coated):

  • Engraved Mamiya-Sekor 1:3.8 f=90mm with no C after the name; chrome front ring on the early barrels
  • Single anti-reflection coating (camera-wiki); the Lenses for Mamiya RB booklet gives 7 elements in 6 groups, picture angle 51°50', minimum aperture 32, screw-in 77 mm hood, 24 7/8 oz (705 g)
  • A second barrel design, the Sekor NB (new barrel), was sold for the 65, 90 and 127 before the C series; Japanese Wikipedia lists it, and no other source consulted describes it³

Mamiya-Sekor C 90mm f/3.8 (1974, multicoated, 7/5 recomputation):

  • C engraved after Sekor on the name ring; black barrel
  • Interchangeable Lenses for Mamiya RB67 booklet: 7 elements in 5 groups, picture angle 52°, minimum aperture 32, screw-in 77 mm hood, 28.3 oz (805 g); the Pro-S manual repeats 7 in 5 and 28-6/16 oz (805 g)
  • Japanese Wikipedia: closest focus 0.2 m from the front rim

Specifications

Formula
7 elements in 6 groups (Sekor); 7 elements in 5 groups (Sekor C)
Construction
7 elements / 6 groups
Aperture range
f/3.8–f/32
Shutter
Seiko #1 leaf shutter in the lens on both versions: T and 1s–1/400, cocked by the body's lever, M-X flash sync at every speed. No B setting; long exposures use T, closed by turning the speed ring toward 1 second
Weight
705 g
Filter
77 mm
Years manufactured
1970
Country
Japan
Coating
Single-coated on the Mamiya-Sekor; multicoated on the Sekor C of 1974

What reviewers say

Optical formula — 7 elements in 6 groups (Sekor); 7 elements in 5 groups (Sekor C)

History

The 90mm f/3.8 is the wide-normal of the Mamiya RB67, the lens Wikipedia has on the camera when it quotes the RB67’s size: 104 × 139 × 226 mm and about 2.69 kg with the 90 mounted. The 1970 RB67 Professional’s manual names it a standard lens with the 127mm f/3.8, and Mamiya’s 1970 Lenses for Mamiya RB booklet gives the first version as 7 elements in 6 groups, a picture angle of 51°50’, minimum aperture f/32, a screw-in 77 mm hood shared with the 127, 180 and 250, and 705 g. Japanese Wikipedia, citing Mamiya’s catalogue, puts closest focus at 0.198 m from the front rim, which the body’s 46 mm bellows makes possible without any tube. The Seiko #1 shutter offers T and 1 to 1/400 second with M-X sync at every speed, and is cocked by the lever on the body.

The C version of 1974 is the one place in the RB67’s short-lens line where the multicoating came with a change in the glass. Mamiya’s Interchangeable Lenses for Mamiya RB67 booklet lists the 90mm f/3.8C as 7 elements in 5 groups against the 1970 booklet’s 7 in 6, and both booklets print a cross-section on their second page for anyone who wants to compare the drawings. The weight rose from 705 g to 805 g and the picture angle is printed as a round 52°; the Pro-S manual repeats both figures. Closest focus stays at 0.2 m. The Sekor NB barrel that Japanese Wikipedia places between the two for the 65, 90 and 127 is recorded nowhere else consulted, so it appears here as an alias and a single-source note rather than a variant.

The name ring does the sorting. No C after Sekor, and a chrome front ring on the early barrels, is the 1970 lens; C after Sekor is 1974 or later. If the ring is worn, weight settles it: 705 g against 805 g. A ring reading K/L 90mm f/3.5 L is the Pro-SD’s 90 of 1990, an 8-element lens with ultra-low-dispersion glass and a floating element that Mamiya’s own page describes as focusing to 448 mm at 960 g; it is a different maximum aperture and so a different page, though it fits the same bodies once its 7 mm rear ring is removed. Going the other way, either f/3.8 lens on a Pro-SD wants the 7 mm ring Mamiya recommends for light sealing on the wider 61 mm mount.

The reviewers this catalogue indexes have shot the 90 more than they have judged it. Pablo Cruz Villalba on Emulsive ran a Sekor C 90 with a scratched front element next to the 50 and came away preferring the 50 for how close it focuses, with no complaint about the 90’s images. Martti Korhonen’s Emulsive Finnish-sauna portfolio and Robin Kuusela’s Commons frames are made with it and say nothing about it, which is its own kind of verdict for a standard lens. Japan Camera Hunter’s system piece records the running argument over whether the C lenses trail the K/L and finds nothing wrong with his own C glass. Rob Davie’s Emulsive review of the Pro-S names his standard lens as the 90mm f/3.5, the K/L, and so belongs to that page. Nobody found here has compared the 6-group and 5-group lenses on film.

Buying is about the shutter first. 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 dot, and both Mamiya booklets say a lens left unused for a long time should be stored with the shutter released. Check the early single-coated lens for separation in its cemented groups, run the aperture through to f/32, and confirm the M-X lever moves and the hood folds back halfway for the 90 as the booklet describes. No launch price in yen or dollars for either version was found, no serial-number table exists, and the Sekor NB barrel’s date is unknown.

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 90mm f/3.8 (RB67)
The schooner Equator in its shed, Everett, Washington — RB67 Pro S, Sekor 90mm f/3.8, Ektar 100, 1/2 s at f/27 (Jmk7) — Jmk7, via Wikimedia Commons (CC BY-SA 4.0)
Sample photo taken with the Mamiya-Sekor 90mm f/3.8 (RB67)
Call of Cthulhu — RB67, Sekor 90mm, T-Max 100 in ID-11 (Robin Kuusela) — Robin Kuusela from Handen, Sverige, via Wikimedia Commons (Public domain)
Sample photo taken with the Mamiya-Sekor 90mm f/3.8 (RB67)
RB67 with the standard 90mm f/3.8 Sekor, studio shot (FlanellKamerasFilm) — FlanellKamerasFilm, via Wikimedia Commons (CC0)

Sample photo wanted — shot with a Mamiya-Sekor 90mm f/3.8 (RB67)? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $200 across 40 fixed-price listings on 2026-09-19 (middle half $180–$240). First day tracked.

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

Show 85 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 127mm f/3.8 (RB67) · Mamiya-Sekor 180mm f/4.5 (RB67) · Mamiya-Sekor 250mm f/4.5 (RB67) · Mamiya-Sekor 50mm f/4.5 (RB67) · Mamiya-Sekor 65mm f/4.5 (RB67)

Sources (8)

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.