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

Mamiya-Sekor 180mm f/4.5 (RB67)

Mamiya · Mamiya RB67 · 1970

single source, unconfirmed

Also known as: Mamiya 180mm f/4.5 RB67 · Mamiya RB67 180mm f4.5 · Mamiya-Sekor 180mm f/4.5 · Mamiya-Sekor C 180mm f/4.5 · Mamiya Sekor C 180mm f4.5 · Mamiya K/L 180mm f/4.5 L · KL 180mm f/4.5 L · Mamiya 180 4.5 RB · セコール 180mm F4.5 · セコールC 180mm F4.5 · マミヤ RB67 180mm · マミヤ KL 180mm F4.5

Variants & identification

Variant Mount Years Serial ranges Production
Mamiya-Sekor 180mm f/4.5 (1970 original, single-coated) · Seiko #1 mechanical leaf shutter, 1s–1/400 and T Mamiya RB67 1970–1974 — —
Mamiya-Sekor C 180mm f/4.5 (1974, multicoated) · Seiko #1 mechanical leaf shutter, 1s–1/400 and T Mamiya RB67 1974–1990 — —
Mamiya K/L 180mm f/4.5 L (1990, Pro-SD generation) · 4 elements in 3 groups, Tessar type · Seiko #1 mechanical leaf shutter, 1s–1/400, T and B Mamiya RB67 1990 — —
  1. Sekor C figures (5 elements in 3 groups, 28°, f/45, 77 mm, 875 g) are from the RB67 Pro-S instruction book at butkus.org; the original and K/L element counts are from camera-wiki and Japanese Wikipedia, which agree with each other, and closest-focus distances are from Japanese Wikipedia only.
  2. The 1970 start year follows camera-wiki's list of original lenses. The RB67 Professional instruction book at butkus.org prints specification blocks only for the 65, 90, 127 and 250, so the 180's actual first year is unconfirmed.
  3. Generation years are the body years (Pro-S 1974, Pro-SD September 1990); no Mamiya document consulted gives a changeover date for the 180 itself, and old stock overlapped.
How to tell them apart (expand)
  • The name ring sorts the three: MAMIYA-SEKOR with a chrome front ring is the 1970 lens, SEKOR C the 1974 multicoated lens, and K/L (or KL … L-A) with no Sekor name the 1990 lens
  • A K/L lens has a removable 7 mm adapter ring at the rear; the two Sekor versions need a separate mounting ring to sit correctly on a Pro-SD or an RZ67
  • Only the K/L has four elements; a Sekor or Sekor C has five, so a service sheet or a count of reflections separates a re-ringed lens
  • Every version takes 77 mm screw-in filters and focuses on the body's bellows, so there is no focusing ring on the lens

Mamiya-Sekor 180mm f/4.5 (1970 original, single-coated):

  • Engraved MAMIYA-SEKOR 1:4.5 f=180mm with no C after the name; chrome front ring (the original RB67 lenses have a single anti-reflective coating, camera-wiki)
  • 5 elements in 3 groups, 77 mm screw-in filter (camera-wiki; Japanese Wikipedia: 3群5枚, φ77mmねじ込み)
  • Needs the lens mount adapter ring on a Pro-SD body, whose throat is 7 mm larger (Pro-SD manual)

Mamiya-Sekor C 180mm f/4.5 (1974, multicoated):

  • C after Sekor on the name ring; black barrel; multicoated (camera-wiki: 'The C lenses were released with the RB67 Pro-S in 1974. These lenses are multi-coated.')
  • Pro-S instruction book: 5 elements in 3 groups, picture angle 28°, minimum aperture f/45, 77 mm filter, screw-in hood, 875 g
  • Closest focus 0.847 m measured from the front rim, on the body's own bellows (Japanese Wikipedia)
  • Two-letter date-code sticker on the rear of the lens: year letter then month letter (Mamiya Repair)

Mamiya K/L 180mm f/4.5 L (1990, Pro-SD generation):

  • K/L on the barrel and no Sekor name (Japanese Wikipedia: セコール銘が廃止された, the Sekor name was dropped); Japanese sources and some barrels read KL 180mm F4.5 L-A
  • 4 elements in 3 groups (camera-wiki; Japanese Wikipedia: 3群4枚), where both Sekor versions have five in three
  • Ships with a 7 mm lens mount adapter ring for the Pro and Pro-S; the ring comes off for a Pro-SD (Pro-SD manual; Japanese Wikipedia)
  • Closest focus 1.099 m (Japanese Wikipedia product list); minimum aperture f/45 (camera-wiki)

Serial-range notes

two-letter sticker on the rear of the lens
Mamiya dated RB and RZ lenses with a two-letter code stuck to the back of the lens: the first letter is the year, the second the month, A = January. Year letters run A–J for 1971–1980, A–T for 1981–2000 and A–N for 2001–2014, so the decade has to be read from the generation (Mamiya Repair). No serial-to-year table for the 180 has been published.

Specifications

Formula
5 elements in 3 groups (Mamiya-Sekor and Sekor C); 4 elements in 3 groups, Tessar type, on the K/L
Construction
5 elements / 3 groups
Aperture range
f/4.5–f/45
Shutter
Seiko #1 mechanical leaf shutter in every version, 1s–1/400 and T, flash sync at all speeds; the K/L adds a B setting (Pro-SD manual). Focusing is by the body's bellows, so the lens has no helicoid.
Weight
875 g
Filter
77 mm
Years manufactured
1970
Country
Japan
Coating
Single coating on the 1970 Mamiya-Sekor; multicoated from the Sekor C of 1974; improved coatings again on the K/L of 1990 (camera-wiki)

What reviewers say

Optical formula — 5 elements in 3 groups (Mamiya-Sekor and Sekor C); 4 elements in 3 groups, Tessar type, on the K/L

No cross-section found: the RB67 Professional, Pro-S and Pro-SD instruction books and the APO lens booklet at butkus.org print specification blocks and depth-of-field tables without optical diagrams, and no Mamiya data sheet for the 180 is online.

History

The 180mm f/4.5 is the RB67’s short telephoto, the portrait length of a 6×7 system whose normal lens is the 90 or the 127. Like every RB lens it carries its own Seiko #1 leaf shutter, 1 second to 1/400 with flash sync throughout, and no focusing helicoid: the body’s bellows do the focusing, which is why the closest distances quoted for it are given from the front rim and vary with the body. Three generations wore the name. The original Mamiya-Sekor of the RB67 Professional era is single-coated with a chrome front ring; the Sekor C of 1974, sold with the Pro-S, is multicoated and black; and the K/L of 1990, the Pro-SD’s lens, drops the Sekor name altogether and reads K/L, with Japanese sources and some barrels adding L-A.

The Sekor C is the one with a full maker specification. The Pro-S instruction book gives 5 elements in 3 groups, a picture angle of 28°, a minimum aperture of f/45, a 77 mm filter thread, a screw-in hood and 875 g. camera-wiki and Japanese Wikipedia give the same five-in-three count for the original lens, and Japanese Wikipedia puts the C’s closest focus at 0.847 m from the front rim. The K/L is a different lens: four elements in three groups, the same count as the RZ67’s Z 180mm f/4.5 W-N, which Mamiya’s Pro IID brochure calls “a Tessar type”, and Japanese Wikipedia’s 1.099 m closest focus for the K/L is the figure Mamiya prints for the RZ M 180mm L SB with its spacer. That the two share glass is an inference from those numbers; no Mamiya document consulted says so, and no weight for either the original or the K/L has been found.

Compatibility is the practical difference between generations. The Pro-SD of September 1990 enlarged the lens throat from 54 to 61 mm, so a K/L lens comes with a 7 mm adapter ring at the rear that stays on for a Pro or Pro-S and comes off for a Pro-SD. The two Sekor versions go the other way: Reznitsky’s chart and the RZ67 Pro IID manual recommend a separate lens mounting ring when a C lens is used on a Pro-SD or an RZ67, and the pre-1978 lenses are listed as not usable on an RZ at all. On an RZ body any RB lens works with the bellows extended a further 7 mm and the speeds set on the lens ring, at the RBL position on a Pro II.

Reviewers do not argue about the optics. Mark Foster at Japan Camera Hunter trusts “all RB lenses are grotesquely sharp” and describes the C-versus-K/L question as a division among photographers rather than something he has seen in his own C lens; Rob Davie at Emulsive names the 180 C or K/L as the first lens to add to a 90mm outfit; Lucas Pollet shot his 5 Frames on a Pro SD with the C and remarks only that it is on the slower end. On the RB67 Flickr group the 180 is called “so sharp” and “very three-dimensional”, lighter and easier to hand-hold than the 250, and the natural portrait length. The one caution in the reviews is Scott McClarin’s, that older RB lenses show more chromatic aberration than the C lenses.

What to check is the shutter. These are fifty-year-old Seiko mechanisms: fire every speed, listen for the slow speeds hanging, and confirm the cocking lever on the body returns and that the lens’s own cocking works on and off the camera. Mike on the rec.photo medium-format group notes that until the shutter is serviced “there is really no way to tell the condition of the shutter” from photographs, and that the latest C lenses have matte-black blades. A two-letter date-code sticker on the back of the lens gives year and month once the decade is known from the generation. Still open: the first year of the 180 itself, which is missing from the 1970 instruction book; the weight of the original and K/L versions; whether the K/L’s L-A suffix denotes a floating group as it does on the RZ lenses; and any list price in yen or dollars, none having been found.

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 180mm f/4.5 (RB67)
Mamiya RB67 Pro S with the Sekor 180mm f/4.5 (Benjamin Balázs) — Benjamin Balázs, via Wikimedia Commons (CC0)
Sample photo taken with the Mamiya-Sekor 180mm f/4.5 (RB67)
Autumn flowers on expired Fuji Superia 100, RB67 Pro S with the Sekor C 180mm f/4.5 (Benjamin Balázs) — Benjamin Balázs, via Wikimedia Commons (CC0)
Sample photo taken with the Mamiya-Sekor 180mm f/4.5 (RB67)
Ilford Delta 400, RB67 Pro SD with the 180mm lens (Hansaem Lee) — Hansaem Lee, via Wikimedia Commons (CC BY 3.0)

Sample photo wanted — shot with a Mamiya-Sekor 180mm f/4.5 (RB67)? We'd love to feature it (with credit).

Live listings

Asking price, USD: a median of $130 across 13 fixed-price listings on 2026-09-19 (middle half $90–$150). First day tracked.

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

Show 20 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 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 (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.