MAMIYA M645
The Mamiya M645 is the original model in Mamiya's line of 6×4.5cm medium format single-lens reflex (SLR) cameras. It came out in 1975. It was the first system camera to offer interchangeable film backs, lenses, and viewfinders in a fairly compact 645 body. Professionals and advanced amateurs who wanted portability without giving up image quality had a new option.
Overview
The M645 was the first commercially successful 6×4.5cm SLR system camera. Before it, most medium format cameras were either large, heavy press cameras or bulkier roll film SLRs like the Bronica SQ or Hasselblad 500 series. The M645 was smaller and lighter and still had professional-grade modularity. Portrait, wedding, and commercial photographers used it in the studio and in the field. They needed high resolution but wanted to move around more than 6×6 or 6×7 systems allowed.
The M645 has a durable metal chassis and a mechanical focal-plane shutter. The design is modular: interchangeable film inserts (including 120 and 220 rollfilm), removable viewfinders, and a wide array of C-series lenses. The 6×4.5cm negative gives 15 exposures per 120 roll, a practical balance between film economy and image detail. The base camera has no built-in light meter. You use an external meter or an optional metered prism, which fits the era, since many professionals used handheld meters then.
The M645 established Mamiya's reputation in the professional medium format market. Later models followed: the M645 1000s, the M645J, and eventually the electronic M645 Super and Pro models. By modern standards it is mechanically simple. It is still valued for its sturdy construction, optical quality, and system flexibility.
Specifications
| Specification | Value |
| Type | Single-Lens Reflex (SLR) |
| Film Format | 6×4.5 cm on 120/220 rollfilm |
| Years Produced | 1975–1987 |
| Lens Mount | M645 screw-mount (C-mount, 65mm flange focal distance) |
| Shutter | Vertical-travel focal-plane shutter, speeds 1 – 1/500 sec, B, X-sync at 1/60 sec |
| Metering | None (body-only); optional with metered pentaprism finders |
| Exposure Modes | Manual only |
| Viewfinder | Interchangeable (waist-level, pentaprism, metered prism options) |
| Dimensions | 138 × 95 × 105 mm (W×H×D), approx. 950 g (body only) |
Key Features
- First 6×4.5cm SLR system camera with fully interchangeable components, including film backs, viewfinders, and lenses.
- Compact and lightweight design for a medium format SLR, making it highly portable compared to 6×6 and 6×7 systems.
- Mechanical reliability with no battery dependency for shutter operation (except metered prisms).
- Interchangeable film inserts allow quick switching between 120 and 220 film without reloading.
- Extensive lens ecosystem with Mamiya C-series lenses (55mm to 500mm), many featuring leaf shutters for flash sync at all speeds.
Historical Context
Mamiya launched the M645 in 1975. Medium format then was dominated by square-format systems like the Hasselblad 500C/M and Bronica SQ-A. Those cameras gave excellent image quality but were large, heavy, and expensive. Mamiya saw room for a more affordable, portable medium format SLR with professional capabilities. The 6×4.5cm format was already popular in twin-lens reflex (TLR) and rangefinder cameras. It suited the job because it gave more frames and used less film.
By introducing a modular 645 SLR, Mamiya opened up medium format to working professionals and serious enthusiasts. Competitors such as Bronica answered with their own 645 models (e.g., the Bronica SQA in 1980), but Mamiya kept an early lead in system integration and lens variety. Wedding and portrait photographers liked the M645 in particular. They needed reliable performance, shallow depth-of-field control, and high-resolution negatives - all in a package that could be hand-held for extended periods.
Collectibility & Value
The Mamiya M645 is moderately collectible today. It is valued more for its historical significance and utility than as a rare collector's item. Units in good working condition typically sell for $200 - $400 on the used market, depending on included accessories such as film backs, viewfinders, and lenses. Fully functional sets with metered prisms and a standard 80mm f/2.8 lens command higher prices. The camera is mechanically simple and sturdy, so many examples still work decades after production ended.
When buying an M645, check the shutter at all speeds. Check for mirror slap noise or binding, and make sure the film advance lever works smoothly. Replace the light seals if they have deteriorated. They commonly degrade and cause light leaks. The interchangeable film backs are generally reliable, but check for proper dark slide insertion and pressure plate alignment. The camera needs no batteries for basic operation. Metered prisms (such as the AE Prism Finder) use mercury PX625 batteries, now obsolete, so you need modern equivalents or adapters. The M645 is durable and repairable, and it is a practical entry point into medium format film photography.
Similar Cameras
- Bronica SQA – A competing 6×4.5cm SLR introduced in 1980 with built-in metering and similar modularity.
- Pentax 6×45 – A lightweight, fixed-back 645 SLR known for its portability and affordability.
- Hasselblad 2000FC – A later-generation 6×4.5cm Hasselblad, more compact than 500-series but less common.
- Konica Autoreflex T3-based 645 prototypes – Experimental models, not mass-produced.
- Fuji GX680 – Larger format, but shares modular philosophy; not directly comparable in size.
Repair & Maintenance
The Mamiya M645 needs no batteries for shutter or film advance operation, so it is highly reliable in the field. Optional metered viewfinders (e.g., the AE Prism Finder) take a 1.35V mercury PX625 battery, which is no longer manufactured. Modern 1.5V substitutes may affect meter accuracy unless compensated with resistors or step-down adapters. The focal-plane shutter is durable but can develop timing inaccuracies over decades of use, particularly at higher speeds (1/250-1/500 sec). Common issues include worn foam light seals, stiff film advance levers, and mirror damping fluid degradation, which can cause slow mirror return or noise.
Repair of the M645 is generally straightforward for experienced technicians, thanks to its mechanical simplicity and widespread parts availability. The lens mount and film back connections are sturdy, but check alignment if the camera has been dropped or heavily used. Regular cleaning, lubrication, and adjustment (CLA) every 5-10 years is recommended for consistent performance. Because of the system's age, original spare parts may require donor bodies or specialized suppliers. The M645's longevity and popularity ensure continued support within the film photography community.
Market Value
┌──────────────────────────────────────────────────────────────────────────┐ │ MAMIYA M645 Aug 2026 │ ├──────────────────────────────────────────────────────────────────────────┤ │ High $13,596 Latest $450 │ │ Median $4,889 Trend ▼ Down │ │ Low $230 Volume ~19/mo │ ├──────────────────────────────────────────────────────────────────────────┤ │$20,000 ┤ │ │ │ │ │ │ │ │$11,514 ┤ . . ... │ │ │ .. ..... .... .. ... │ │ │ . . ... ............ .. . │ │ │. . .................... │ │ $200 ┤ . . . ... .. . . . ..........│ │ ├─────────────────────────────────────────────────────────────────│ │ vol │▁ ▂ ▁ ▁ ▁ ▅▂▄▂▅▅▅█▁▇▄▇█▃▂█▅▆▅▅▁▂▁▁▇▄▃▆▄▅▁│ │ └─────────────────────────────────────────────────────────────────│ │ 2025-11 2026-03 2026-08│ └──────────────────────────────────────────────────────────────────────────┘
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