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

Mamiya M645

Mamiya · Mamiya 645 mount · 6×4.5cm on 120 film (56×41.5mm), fixed back with interchangeable 120 and 220 inserts; no mid-roll change · 1975

single source, unconfirmed

Also known as: Mamiya M645 · Mamiya 645 · Mamiya M645 1000S · Mamiya 645 1000S · M645 1000S · M645 1000 S · Mamiya M645J · Mamiya M645 J · マミヤ M645 · マミヤ M645 1000S · マミヤ 645 · 6x4.5 · 6×4.5

Variants & identification

Variant Mount Years Serial ranges Production
M645 Mamiya 645 1975–1987 — —
M645 1000S Mamiya 645 1976–1990 — —
M645 J Mamiya 645 1979–1982 — —
  1. Family weight is the 1000S outfit with Waist-Level Finder S and 80mm f/2.8 (1405g) from the manual; no manual figure for a bare body was found.
  2. The M645 J's export-only status is camera-wiki's statement alone; the self-timer variant on the 1000S is marked self_timer: false at family level because two of the three bodies lack it.
  3. Camera-wiki's 99.3 × 84 × 109mm for the M645 is presumably body only; the 1000S manual measures with finder and lens.
How to tell them apart (expand)
  • Boxy body with a folding crank on the right, two shutter buttons (front and top) on the M645 and 1000S, one on the J
  • Fixed back that swings open; the whole insert lifts out, no dark slide
  • Battery chamber in the base for one 6V cell; green battery-check LED
  • Nameplate: M645, M645 1000S or M645 J

M645:

  • Nameplate reads M645 with no 1000S; shutter speed dial tops out at 1/500 (camera-wiki)
  • Mirror lock-up lever and a second shutter release on the front, no self-timer and no depth-of-field preview lever (camera-wiki; English Wikipedia)

M645 1000S:

  • 1000S on the nameplate; dial marked to 1/1000
  • Self-timer (5–10s) and a spring-loaded depth-of-field preview lever on the body (1000S manual)
  • Mirror lock-up lever, multiple-exposure lever, two release buttons and a lock ring for both (1000S manual)

M645 J:

  • J on the nameplate; 1/500 top speed
  • No mirror lock-up knob and no second (front) shutter button (English Wikipedia; camera-wiki)

Serial-range notes

Two-letter gold sticker
Mamiya's date code on bodies and lenses of this era is a small gold sticker with two letters, year then month, A–J for 1971–80 and A–T for 1981–2000 (Mamiya Repair).

Specifications

Format
6×4.5cm on 120 film (56×41.5mm), fixed back with interchangeable 120 and 220 inserts; no mid-roll change · 15 on 120; 30 on 220 exposures
Finder
interchangeable: Waist-Level Finder S (folds to an eye-level sports finder), Prism Finder, PD Prism Finder (silicon-cell TTL, 7 LEDs, runs on the body cell), CdS Prism Finder (needle, own SR44), AE Prism Finder · 0.74× magnification
Shutter
moving-coil electronic cloth focal-plane shutter, vertical travel, in the body · 8s–1/500 and B (M645, M645 J); 8s–1/1000 and B (1000S), full stops · flash sync X 1/60, FP contact · no self-timer
Film advance
single-revolution interchangeable crank on the body; the insert cannot be changed mid-roll
Back
fixed, hinged; interchangeable pre-loadable 120 and 220 inserts, counter switches automatically with the insert
Meter
none in body; PD, CdS and AE prism finders meter through the lens
Motor drive
Not compatible — Manual crank only; a power winder grip arrived with the 645 Super
Weight
1405 g
Dimensions
99.3 × 100 × 154 with Waist-Level Finder S and 80mm f/2.8 (1000S manual); weight_g is that outfit; English Wikipedia's bare-body figures are 920g (M645), 965g (1000S), 910g (J) mm
Country
Japan
Accessories
120 and 220 roll-film inserts · Waist-Level Finder S; Prism Finder; PD Prism Finder (S); CdS Prism Finder; AE Prism Finder · Interchangeable focusing screens; sports-finder masks for 110, 150 and 210mm · Hand grips; auto extension rings with meter coupling

0.74× through the Prism Finder with the standard lens, 1.3× through the waist-level magnifier (1000S manual); 94% coverage; interchangeable screen with split-image spot and microprism collar; a hot shoe sits on the prism, not the body

Where sources disagree

Last
  • 1990 — English Wikipedia
  • 1987 — Tim Dobbs (Emulsive), who gives 1975–1987, the M645's dates

Better supported: 1990

What reviewers say

History

The M645 was Mamiya’s answer to a question the RB67 had left open: what a medium-format SLR looks like when it is meant to be held rather than stood on a tripod. Announced in June 1975, it was the first single-lens reflex built for 6×4.5, a frame the Japanese product list gives as 56×41.5mm, fifteen on 120 or thirty on 220. The shutter is in the body, an electronically timed cloth focal-plane shutter of Mamiya’s moving-coil design, 8s to 1/500 in full stops, on one 6V cell; the Japanese list notes that with the cell flat the shutter simply stays open. Flash syncs at 1/60. The film goes in a pre-loadable insert that drops into a fixed back, so there is no dark slide and no changing film mid-roll, which every reviewer counts as the one thing the later 645 Super fixed.

The 1000S of November 1976 is the M645 with a 1/1000 top speed, a 5 to 10 second self-timer and a spring-loaded depth-of-field preview lever, keeping the mirror lock-up, the multiple-exposure lever and the two shutter releases. Its manual gives 1405g with the Waist-Level Finder S and 80mm f/2.8, 1570g with the f/1.9, and 99.3 × 100 × 154mm; English Wikipedia’s bare-body weights are 920g for the M645, 965g for the 1000S. The M645 J of 1979 went the other way: a 1/500 body with the mirror lock-up and the front release removed, sold for export only according to camera-wiki, and gone by 1982. All three take the same 645 bayonet lenses, the same inserts and the same finders, and the lenses and inserts carry over to the 645 Super, though the finders do not.

The finders are the system. The Waist-Level Finder S opens with one touch and folds into an eye-level sports finder with masks for the 110, 150 and 210mm lenses; the plain Prism Finder gives 0.74× with the standard lens and carries the hot shoe; the PD Prism Finder meters through the lens with a silicon cell and seven LEDs, taking its power from the body; the CdS Prism Finder has a needle and its own SR44; the AE prism adds aperture priority. Mike Eckman’s 1,720g for a body with 80mm and PD prism is what a metered outfit weighs, and Wyatt Ryan’s “at least two and a half pounds” is the same camera.

Telling them apart is the nameplate and the dial: 1000S and a 1/1000 mark, J and a single shutter button, plain M645 with two buttons and 1/500. Date codes are the two-letter gold sticker, year then month.

Buying advice from the reviews is consistent. Mike Eckman says to confirm an insert is included and the electronics fire at every speed, since the shutter does nothing without power. Tim Dobbs warns about mirror slap below 1/60 hand-held and the 1/60 sync for fill flash; the mirror lock-up on the M645 and 1000S is the answer on a tripod. Check the battery-check LED, the crank’s single-revolution wind and the light seals on the hinged back, and expect a loud mirror. At the prices these sell for, the 1000S with an 80mm f/2.8 and a waist-level finder is the usual first medium-format camera; Dobbs paid £249 for exactly that in 2012.

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.

Photographs

Mamiya M645
Mamiya M645 1000S without lens — Gürkan Sengün, via Wikimedia Commons (CC BY-SA 3.0)
Mamiya M645
Mamiya M645 with 80mm lens and waist-level finder open — FlanellKamerasFilm, via Wikimedia Commons (CC0 1.0)
Mamiya M645
Mamiya M645 with the 70mm leaf-shutter lens — E Magnuson, via Wikimedia Commons (CC BY 2.0)

Live listings

Asking price, USD: a median of $350 across 75 fixed-price listings on 2026-09-19 (middle half $120–$500). First day tracked.

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

Show 154 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 645 Super / Pro / Pro TL · Mamiya C220 · Mamiya C330 · Mamiya RB67 · Mamiya RZ67

Lenses for this body: Mamiya-Sekor C 110mm f/2.8 (645) · Mamiya-Sekor C 150mm f/3.5 (645) · Mamiya-Sekor C 45mm f/2.8 (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 (7)

Every page here is assembled from public sources, and the gaps are real ones. If you own this camera, 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.