Mamiya M645

Medium format MF film SLR camera


Production details
System: Mamiya M645 (1975)
Imaging plane
Maximum format:Medium format 6x4.5
Mount and Flange focal distance:Mamiya M645 [63mm]
Imaging plane:56 × 41.5mm film
Model:Electronically controlled
Speeds:8 - 1/500 + B
Exposure metering:None
Exposure modes:Manual
Physical characteristics

Manufacturer description

The Mamiya M645 is a 6 x 4.5cm large-negative SLR that is both extremely versatile and compact.

1. Large-Negative Quality

The 6 x 4.5cm format offers approximately 3 times more area than the 35mm format. Moreover, unlike the 6x6cm square negative, there is little waste of the negative area. For beautiful color enlargements everytime, the 6x4.5cm format is the ideal format.

2. Compact Design

Despite the large-negative it produces, the Mamiya M645 is designed to handle as easily as a 35mm SLR. Its compact size and light weight are perfectly suited for the action photographer. It fits so well into one's hands that it becomes an extension of his reflexes.

3. Mamiya's Moving Coil Electronic Shutter

Mamiya has developed a revolutionary Moving Coil Electronically Controlled Shutter for the Mamiya M645. Electrical consumption of this new shutter is approximately 1/10 that of previous electronic shutters. Furthermore, consumption remains constant regardless of the shutter speed being used. In addition to accuracy, long battery life is assured by this new shutter.

4. Large, Bright Viewfinder

It becomes easy to catch the peak of action when looking through the large, bright viewfinder. Because of the Mamiya M645's automatic diaphragm and quick-return mirror, the viewfinder never grows dim. It is always bright, ready for the next photograph.

5. Interchangeable Finders

Lightweight, dual-function Waist-Level Finder S

A compact and lightweight finder which opens and closes with a single touch, the Waist-Level Finder S is ideal for copying, close-ups, low and high angle pictures, and working in dim light. Additionally, it is instantly convertible to an eye-level sports finder which accurately shows the fields for the 80, 110, 150, and 210 mm lenses, allowing one to easily follow the quickest action.

Prism Finder

The Prism Finder is well-suited for action photography. Whether the vertical or horizontal format is utilized, focusing and following action is as easy as on a 35mm SLR.

AE (Automatic Exposure) Prism Finder

The AE Prism Finder combines an electronic shutter control mechanism and a TTL-type CdS exposure meter to provide aperture-priority, fully automatic exposure.

PD Prism Finder

The PD Prism Finder employs silicon cells for full-aperture, center-weighted readings. It is your assurance that every negative will be properly exposed.

CdS Prism Finder with built-in meter

Accurate through-the-lens exposure measurement is possible with the CdS Prism Finder which couples to the aperture of the lens and indicates the proper shutter speed to set on the camera.

6. Flatness of the Film Plane

Developed through Mamiya's long experience as a manufacturer of 120/220 roll-film cameras, the Roll-Film Inserts for the Mamiya M645 keep the film perfectly flat for edge-to-edge sharpness. Inserts are available for 120 or 220 roll-film.

7. Multi-Coated Lenses

Mamiya-Sekor lenses have achieved world-renown as professional lenses of exceptional contrast, high resolution, clear definition, and excellent color balance. All the lenses for the Mamiya M645, from wide-angle to telephoto, have been multi-coated to maintain their high standard of performance even under adverse lighting.

8. Unlimited Scope

A full range of accessories are available for the Mamiya M645 to assist the photographer in capturing virtually any type of image. Accessories include hand grips, interchangeable focusing screens, and auto extension rings complete with meter coupling.

Multiple-Exposure Provision

Merely lowering the multiple-exposure lever allows the photographer to take as many multiple-exposures as he wishes. During multiple-exposures, the exposure counter does not move.

Mirror Lock-Up

The Mamiya M645 is designed to have minimal mirror shock; nevertheless, when it is necessary to completely eliminate vibrations, all you have to do is lock the mirror in the up position. To do so, simply lower the mirror lock-up lever. Mirror lock-up provision makes close-up and telephoto photography possible even at slow shutter speeds.

Two Shutter Release Buttons

The Mamiya M645 is equipped with two ideally located shutter release buttons, so that regardless of how you hold the camera, there is always a release button at your finger tips.


CAMERA TYPE: 6 x 4.5cm electronic focal-plane shutter SLR.

FILM TYPE: 120 roll-film for 15 exposures. 220 roll-film for 30 exposures.

ROLL FILM INSERT: Interchangeable, two types available for 120 and 220 size roll films. Actual negative size 56 x 41.5mm.

LENS MOUNT: Mamiya M645 bayonet mount.

SHUTTER: B, 8-1/500 sec. Moving Coil Electronic Focal-Plane Shutter, FP and X (1/60 sec.) synchronization, Shutter release lock provision.

BATTERY TYPE: One 6V silver-oxide battery 4SR44 or 6V alkaline battery 4LR44.

FOCUSING METHOD: Each Mamiya-Sekor lens is equipped with its own helicoid focusing mount.

FOCUSING SCREEN: Microprism center spot (standard focusing screen), surrounding area is matte, with Fresnel lens, focusing screen interchangeable, 94% of the picture area visible.

MIRROR: Instant return, with mirror lock-up provision.

FILM TRANSPORT: Film transport by a single turn of the crank-equipped film advance knob. Provision to prevent double exposure.

EXPOSURE COUNTER: Progressive type, automatic reset, automatic changeover with insertion of 120/220 roll-film inserts.

BATTERY CHECK: Depressing B.C button illuminates green L.E.D. if battery condition is satisfactory.

MULTIPLE-EXPOSURE: Lowering multiple-exposure lever makes multiple-exposures possible; exposure counter does not move during multiple-exposures.


Prism Finder: The image in the Prism Finder is right-side up, laterally correct, and moves in the correct direction; magnification of 0.74x with the standard lens at infinity; built-on hot-shoe; comes with eyecup.

AE Prism Finder: Aperture-priority, automatic exposure prism finder with built-in electronic shutter control mechanism and CdS exposure meter. Through-the-lens, center-weighted, full-aperture metering with shutter speed in the viewfinder. Meter coupling range is EV2.85 - EV17 (f/1.9, 1/2 sec. - f/16, 1/500 sec.) with f/1.9 lens and ASA 100 film. With the f/2.8 lens, the meter coupling range is EV4 - EV18 (f/2.8, 1/2 sec. - f/22, 1/500 sec.) using ASA 100 film. Camera battery serves as power source. Other features same as for Prism Finder.

PD Prism Finder S: Prism Finder with built-in silicon cell, through-the-lens, full-aperture, center-weighted metering; 7 LEDs visible in the viewfinder for correct or compensated exposure; with 100 ASA and f/1.9 lens, meter coupling range of EV -1.15 - +18 (f/1.9, 8 sec. - f/22, 1/500 sec.); with f/2.8 lens, EV 0 - 18 (f/2.8, 8 sec. - f/22, 1/500 sec.); camera body battery serves as power source; other features same as Prism Finder.

CdS Prism Finder: Prism Finder with CdS through-the-lens full-aperture, center-weighted metering; zero method with indicator needle; couples to aperture and shutter speed manually set; power source, one 1.5V silver oxide battery SR44 or alkaline battery LR44; with 100 ASA and f/1.9 lens, meter coupling range of EV 2.85 - 17 (f/1.9, 1/2 sec. - f/16, 1/500 sec.); with f/2.8 lens, EV 4 - 18 (f/2.8, 1/2 sec. - f/22, 1/500 sec.), other features same as Prism Finder.

Waist-Level Finder S: Opens and closes with a single touch; magnification of 1.3X (w/standard lens at infinity); diopter correction lenses interchangeable with standard magnifier; built-in sports finder shows field for standard lens and accepts a mask for 110, 150, and 210mm lenses, all fields showing approximately 80% of the picture-taking area.

From the editor

The weight and dimensions are indicated for the camera body with the Mamiya-Sekor C 80mm F/1.9 lens mounted.

Notify of

Copy this code

and paste it here *

Inline Feedbacks
View all comments

Copyright © 2012-2023 Evgenii Artemov. All rights reserved. Translation and/or reproduction of website materials in any form, including the Internet, is prohibited without the express written permission of the website owner.

35mm full frame

43.27 24 36
  • Dimensions: 36 × 24mm
  • Aspect ratio: 3:2
  • Diagonal: 43.27mm
  • Area: 864mm2

Unable to follow the link

You are already on the page dedicated to this lens.

Cannot perform comparison

Cannot compare the lens to itself.

Image stabilizer

A technology used for reducing or even eliminating the effects of camera shake. Gyro sensors inside the lens detect camera shake and pass the data to a microcomputer. Then an image stabilization group of elements controlled by the microcomputer moves inside the lens and compensates camera shake in order to keep the image static on the imaging sensor or film.

The technology allows to increase the shutter speed by several stops and shoot handheld in such lighting conditions and at such focal lengths where without image stabilizer you have to use tripod, decrease the shutter speed and/or increase the ISO setting which can lead to blurry and noisy images.

Original name

Lens name as indicated on the lens barrel (usually on the front ring). With lenses from film era, may vary slightly from batch to batch.


Format refers to the shape and size of film or image sensor.

35mm is the common name of the 36x24mm film format or image sensor format. It has an aspect ratio of 3:2, and a diagonal measurement of approximately 43mm. The name originates with the total width of the 135 film which was the primary medium of the format prior to the invention of the full frame digital SLR. Historically the 35mm format was sometimes called small format to distinguish it from the medium and large formats.

APS-C is an image sensor format approximately equivalent in size to the film negatives of 25.1x16.7mm with an aspect ratio of 3:2.

Medium format is a film format or image sensor format larger than 36x24mm (35mm) but smaller than 4x5in (large format).

Angle of view

Angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

As the focal length changes, the angle of view also changes. The shorter the focal length (eg 18mm), the wider the angle of view. Conversely, the longer the focal length (eg 55mm), the smaller the angle of view.

A camera's angle of view depends not only on the lens, but also on the sensor. Imaging sensors are sometimes smaller than 35mm film frame, and this causes the lens to have a narrower angle of view than with 35mm film, by a certain factor for each sensor (called the crop factor).

This website does not use the angles of view provided by lens manufacturers, but calculates them automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),


CF – crop-factor of a sensor,
FL – focal length of a lens.


A lens mount is an interface — mechanical and often also electrical — between a camera body and a lens.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock type. Modern camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body, unlike screw-threaded mounts.

Lens mounts of competing manufacturers (Canon, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance can also be different.

The flange focal distance (FFD) is the distance from the mechanical rear end surface of the lens mount to the focal plane.

Lens construction

Lens construction – a specific arrangement of elements and groups that make up the optical design, including type and size of elements, type of used materials etc.

Element - an individual piece of glass which makes up one component of a photographic lens. Photographic lenses are nearly always built up of multiple such elements.

Group – a cemented together pieces of glass which form a single unit or an individual piece of glass. The advantage is that there is no glass-air surfaces between cemented together pieces of glass, which reduces reflections.

Focal length

The focal length is the factor that determines the size of the image reproduced on the focal plane, picture angle which covers the area of the subject to be photographed, depth of field, etc.


The largest opening or stop at which a lens can be used is referred to as the speed of the lens. The larger the maximum aperture is, the faster the lens is considered to be. Lenses that offer a large maximum aperture are commonly referred to as fast lenses, and lenses with smaller maximum aperture are regarded as slow.

In low-light situations, having a wider maximum aperture means that you can shoot at a faster shutter speed or work at a lower ISO, or both.

Closest focusing distance

The minimum distance from the focal plane (film or sensor) to the subject where the lens is still able to focus.

Closest working distance

The distance from the front edge of the lens to the subject at the maximum magnification.

Magnification ratio

Determines how large the subject will appear in the final image. For example, a magnification ratio of 1:1 means that the image of the subject formed on the film or sensor will be the same size as the subject in real life. For this reason, a 1:1 ratio is often called "life-size".

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Electronic manual focus override is performed in the following way: half-press the shutter button, wait until the camera has finished the autofocusing and then focus manually without releasing the shutter button using the focusing ring.

Manual diaphragm

The diaphragm must be stopped down manually by rotating the detent aperture ring.

Preset diaphragm

The lens has two rings, one is for pre-setting, while the other is for normal diaphragm adjustment. The first ring must be set at the desired aperture, the second ring then should be fully opened for focusing, and turned back for stop down to the pre-set value.

Semi-automatic diaphragm

The lens features spring mechanism in the diaphragm, triggered by the shutter release, which stops down the diaphragm to the pre-set value. The spring needs to be reset manually after each exposure to re-open diaphragm to its maximum value.

Automatic diaphragm

The camera automatically closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Fixed diaphragm

The aperture setting is fixed at F/ on this lens, and cannot be adjusted.

Number of blades

As a general rule, the more blades that are used to create the aperture opening in the lens, the rounder the out-of-focus highlights will be.

Some lenses are designed with curved diaphragm blades, so the roundness of the aperture comes not from the number of blades, but from their shape. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.

At maximum aperture, the opening will be circular regardless of the number of blades.


Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

Maximum diameter x Length

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

For lenses with collapsible design, the length is indicated for the working (retracted) state.

Weather sealing

A rubber material which is inserted in between each externally exposed part (manual focus and zoom rings, buttons, switch panels etc.) to ensure it is properly sealed against dust and moisture.

Lenses that accept front mounted filters typically do not have gaskets behind the filter mount. It is recommended to use a filter for complete weather resistance when desired.

Fluorine coating

Helps keep lenses clean by reducing the possibility of dust and dirt adhering to the lens and by facilitating cleaning should the need arise. Applied to the outer surface of the front and/or rear lens elements over multi-coatings.


Lens filters are accessories that can protect lenses from dirt and damage, enhance colors, minimize glare and reflections, and add creative effects to images.

Lens hood

A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the sun, bright studio lights, or a bright white background.

The geometry of the lens hood can vary from a plain cylindrical or conical section to a more complex shape, sometimes called a petal, tulip, or flower hood. This allows the lens hood to block stray light with the higher portions of the lens hood, while allowing more light into the corners of the image through the lowered portions of the hood.

Lens hoods are more prominent in long focus lenses because they have a smaller viewing angle than that of wide-angle lenses. For wide angle lenses, the length of the hood cannot be as long as those for telephoto lenses, as a longer hood would enter the wider field of view of the lens.

Lens hoods are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.


Teleconverters increase the effective focal length of lenses. They also usually maintain the closest focusing distance of lenses, thus increasing the magnification significantly. A lens combined with a teleconverter is normally smaller, lighter and cheaper than a "direct" telephoto lens of the same focal length and speed.

Teleconverters are a convenient way of enhancing telephoto capability, but it comes at a cost − reduced maximum aperture. Also, since teleconverters magnify every detail in the image, they logically also magnify residual aberrations of the lens.

Lens caps

Scratched lens surfaces can spoil the definition and contrast of even the finest lenses. Lens covers are the best and most inexpensive protection available against dust, moisture and abrasion. Safeguard lens elements - both front and rear - whenever the lens is not in use.