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

Mamiya-Sekor 127mm f/3.8 (RB67)

Mamiya · Mamiya RB67 · 1970

single source, unconfirmed

Also known as: Mamiya RB67 127mm f/3.8 · Mamiya RB67 127mm f3.8 · Mamiya-Sekor 127mm f/3.8 · Mamiya-Sekor C 127mm f/3.8 · Mamiya Sekor C 127mm f3.8 RB67 · Sekor C 127/3.8 · KL 127mm f/3.5 L · Mamiya K/L 127mm f/3.5 · Mamiya RB67 127mm f/3.5 KL · マミヤ RB67 127mm · セコールC 127mm F3.8 · マミヤ KL 127mm F3.5 L

Variants & identification

Variant Mount Years Serial ranges Production
Mamiya-Sekor 127mm f/3.8 (1970, single-coated) · Seiko #1, T and 1s–1/400, M-X sync Mamiya RB67 1970–1974 — —
Mamiya-Sekor C 127mm f/3.8 (1974, multicoated) · Seiko #1, T and 1s–1/400, M-X sync Mamiya RB67 1974–1990 — —
Mamiya K/L 127mm f/3.5 L (1990, Pro-SD generation) · 6 elements in 4 groups (Mamiya Pro SD lens page; Japanese Wikipedia; camera-wiki) · Seiko #1, T and 1s–1/400, X sync at all speeds Mamiya RB67 1990 — —
  1. Element and group counts, picture angles, minimum apertures, hoods and weights for the Sekor and Sekor C are from Mamiya's own lens booklets and the RB67 Professional and Pro-S manuals as hosted by butkus.org; the K/L figures are from Mamiya's legacy Pro SD lens page. Closest-focus figures (from the front rim) are from Japanese Wikipedia, which cites Mamiya catalogue R790503 and the Pro-SD catalogue.
  2. The site's rule is one focal length and one maximum aperture per family. This page bends it: the K/L 127mm f/3.5 replaced the f/3.8 as the RB67's standard 127 in 1990, Mamiya, sellers and every reference treat the three as one lens line, and a separate page for an f/3.5 would split what buyers search for as 'RB67 127mm'.
  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, Pro-SD September 1990). No source gives a month for the 127's own changeover, and no discontinuation dates are published.
How to tell them apart (expand)
  • Three name rings: Mamiya-Sekor (1970, single-coated, chrome ring early), Mamiya-Sekor C (1974, multicoated) and Mamiya K/L (1990, no Sekor name, f/3.5)
  • The f-number on the ring sorts the K/L from the rest: 3.5 is K/L, 3.8 is Sekor or Sekor C
  • A K/L lens has a removable 7 mm ring at the rear for the older 54 mm mount; Sekor and Sekor C lenses need an adapter ring to sit properly on the Pro-SD's 61 mm mount (Japanese Wikipedia recommends the 7 mm ring 'for better light sealing')
  • Weight sorts the two f/3.8 lenses: 655 g for the Sekor, 750 g for the Sekor C; both take 77 mm filters and a screw-in hood
  • Every version carries a Seiko #1 leaf shutter cocked by the body's lever, with cocking pins on the lens barrel that must be turned fully to the red mark before mounting

Mamiya-Sekor 127mm f/3.8 (1970, single-coated):

  • Engraved Mamiya-Sekor 1:3.8 f=127mm 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 5 elements in 3 groups, picture angle 38°16', minimum aperture 32, screw-in 77 mm hood, 23 1/8 oz (655 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 127mm f/3.8 (1974, multicoated):

  • C engraved after Sekor on the name ring; black barrel with the shutter-speed ring, aperture ring, M-X lever and shutter cocking pins of the whole line
  • Interchangeable Lenses for Mamiya RB67 booklet: 5 elements in 3 groups, picture angle 38°, minimum aperture 32, screw-in 77 mm hood, 26.4 oz (750 g); the Pro-S manual gives the same figures
  • Japanese Wikipedia: closest focus 0.433 m from the front rim; a gold-finished 127mm f/3.8 GL was sold only with the 300-unit RB67 Professional GL of October 1981

Mamiya K/L 127mm f/3.5 L (1990, Pro-SD generation):

  • K/L on the name ring and L after the aperture; no Sekor name (Japanese Wikipedia: the Sekor name was dropped with the KL/L series)
  • Maximum aperture f/3.5 rather than f/3.8, and 6 elements in 4 groups rather than 5 in 3
  • Supplied with a 7 mm mount ring for the 54 mm mount of the Pro and Pro-S; removed, the lens sits directly on the Pro-SD's 61 mm mount (camera-wiki; Japanese Wikipedia; Pro-SD lens instructions)
  • Mamiya's Pro SD lens page: angle of view 39°, minimum aperture 32, closest focus 2 ft 1.2 in / 639 mm, magnification 0.36x, 77 mm filter, screw-in hood, 2.9 × 3.8 in / 74 × 97.2 mm, 1 lb 12 oz / 780 g

Specifications

Formula
5 elements in 3 groups (Sekor, Sekor C); 6 elements in 4 groups (K/L f/3.5)
Construction
5 elements / 3 groups
Aperture range
f/3.8–f/32
Shutter
Seiko #1 leaf shutter in the lens on every version: T and 1s–1/400, cocked by the body's lever, flash sync at every speed (M-X on Sekor and Sekor C, X on K/L). No B setting; long exposures use T, closed by turning the speed ring or, on the K/L, by a cable release in the bulb socket
Min. focus
0.639 m
Weight
655 g
Filter
77 mm
Years manufactured
1970
Country
Japan
Coating
Single-coated on the Mamiya-Sekor; multicoated from the Sekor C of 1974; K/L lenses multicoated

What reviewers say

Optical formula — 5 elements in 3 groups (Sekor, Sekor C); 6 elements in 4 groups (K/L f/3.5)

History

The 127mm f/3.8 is the Mamiya RB67’s long-normal lens, the one the 1970 RB67 Professional’s manual lists as a standard lens beside the 90mm f/3.8, and the lens Mamiya chose for both of its gold-finished commemorative bodies. On the 56 × 68 mm frame it covers 38 degrees, which Mamiya’s own Pro SD page translates as 62 mm on 35 mm film. The 1970 Lenses for Mamiya RB booklet gives the first version as 5 elements in 3 groups, a picture angle of 38°16’, a minimum aperture of f/32, a screw-in 77 mm hood shared with the 90, 180 and 250, and 655 g, the lightest lens in the seven-lens launch line. Like every RB67 lens it carries a Seiko #1 leaf shutter with T and 1 to 1/400 second, cocked by the lever on the body and released from the body or from a cable socket on the lens, with flash sync at every speed.

Three generations wear the name. The single-coated Mamiya-Sekor of 1970 (camera-wiki) was joined by a redesigned Sekor NB barrel for the 65, 90 and 127, which only Japanese Wikipedia records and which is carried here as a single-source claim. The multicoated Mamiya-Sekor C came with the Pro-S in 1974: the same 5-in-3 formula in a barrel that grew to 750 g, and the closest focus from the front rim moved from 0.434 m to 0.433 m, which is to say it did not move. In September 1990 the Pro-SD arrived with a mount widened from 54 to 61 mm and a new lens line that dropped the Sekor name: the Mamiya K/L 127mm f/3.5 L, a fresh 6-element, 4-group computation a third of a stop faster, focusing to 639 mm at 0.36x, 74 mm long and 780 g. K means it fits the Pro and Pro-S once its 7 mm rear ring is removed; L means it fits the Pro-SD as delivered. The site normally keeps one maximum aperture per family, and the table note explains why the f/3.5 sits here rather than on a page of its own.

Telling them apart takes a glance at the name ring. No C and a chrome front ring is the 1970 lens; C after Sekor is 1974 or later; K/L with 3.5 as the aperture is the Pro-SD lens. Weight settles the two f/3.8 versions when the ring is worn, 655 against 750 g. Filters are 77 mm on all three. The Pro-S manual adds one practical note that applies to the C and the K/L alike: extension tube No. 2 on the 127 reaches life size, because the body’s own bellows already give 46 mm of extension.

Reviewers on the sites this catalogue indexes have used the lens far more than they have judged it. Pablo Garcia shot a whole 35mmc portfolio in California fire country on the 127 and, pressed in the comments, said only that the lenses are of stunning image quality; Alex Furman on Emulsive, shooting a scuffed Sekor C 127 at EI 800 on Instax Square, calls its out-of-focus rendering very pleasing while conceding the lens is not famous for it; Japan Camera Hunter’s Bellamy Hunt, writing about the system rather than this focal length, reports the running argument over whether the C lenses trail the K/L and says he has found no shortcoming in his own C glass. Scott McClarin’s Emulsive review of the Pro-S mentions the 127 only as part of his kit, with a general warning that older lenses show more chromatic aberration. Nobody found here has put a Sekor and a K/L 127 side by side on film.

What to check when buying is the shutter before the glass. The Seiko #1 is cocked by the body, and a lens that has sat for years will often fire slow at 1 second or stick at T; the cocking pins on the barrel must be turned all the way to the red dot before mounting, and both Mamiya’s booklets say a lens left unused for a long time should be stored with the shutter released. Check the early single-coated Sekor for separation in its cemented groups, and every version for a smooth, unhesitating aperture at f/32. A K/L 127 sold without its 7 mm ring will not seat on a Pro or Pro-S; a Sekor or Sekor C on a Pro-SD wants the adapter ring Mamiya recommends for light sealing. No launch price in yen or dollars for any 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 127mm f/3.8 (RB67)
Walkway at Izmailovo Island, Moscow, on T-Max 400 — Mamiya RB67 with the 127mm f/3.5 (Def2010) — Def2010, via Wikimedia Commons (CC0)

Sample photo wanted — shot with a Mamiya-Sekor 127mm f/3.8 (RB67)? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $160 across 35 fixed-price listings on 2026-09-19 (middle half $130–$190). First day tracked.

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

Show 92 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 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) · Mamiya-Sekor 90mm f/3.8 (RB67)

Sources (9)

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.