Pentax 645N

Medium format AF film SLR camera

Production details

Production details
Announced:December 1997
Production type:Mass production
System: Pentax 645 (1984)


Imaging plane
Maximum format:Medium format 6x4.5
Mount and Flange focal distance:Pentax 645 [70.87mm]
Imaging plane:56 × 41.5mm film
Model:Electronically controlled
Speeds:4 - 1/1000 + B
Exposure metering:Through-the-lens (TTL)
Exposure modes:Programmed Auto
Aperture-priority Auto
Shutter-priority Auto
Physical characteristics

Manufacturer description #1

The world’s first autofocus medium-format SLR camera.

6cm 4.5cm medium-format image quality: Because of its large image size (2.7 times larger than the 35mm format), the 645N’s 6cm x 4.5cm format is far superior in image quality to 35mm, producing true-to-life pictures with finer details, higher resolution and better color fidelity.

Compact, lightweight body with extra-rugged design and low-noise operation: The 645N’s body is made of rigid aluminum diecast and protected with a glass-fiber reinforced polycarbonate coating approximately 1.7 times thicker than a normal coating. As a result, the 645N is extremely durable and resistant to shock and wear. In addition, special mechanisms are incorporated in the 645N to ensure low-noise, low-shock operation – a particularly important feature in wildlife photography.

Effortless eye-level shooting: The 645N has perfected the renowned optical system – originally developed for and made famous by the Pentax 645 – by adding a high-performance viewfinder lupe. As a result, the camera assures comfortable, fatigue-free eye-level shooting over long periods in the field.

High-precision autofocus system with SAFOX IV: The 645N incorporates the Pentax developed SAFOX IV phase-matching autofocus system to ensure accurate focusing not only on subjects with vertical orientation but also on those with horizontal orientation – even under such poor lighting conditions as EV-1.

Selectable focus frame: The choice of the wider “3-Point AF” frame and the pinpoint “Spot AF” frame allows the photographer to use the most suitable focus frame for each subject and in every situation.

Three focus modes: The 645N offers three focus modes to choose from: “AF Single” activates the shutter only when the subject comes into focus; “AF Servo” lets the user release the shutter at any time; and “Manual Focus” lets the user adjust the focus manually using the focus ring of the lens. In the manual-focus mode, the focus indicator in the viewfinder provides the focus status.

Predictive AF: In the AF Servo mode, the 645N’s AF system detects the subject’s movement (toward or away from the camera) and “predicts” the optimum focusing point at shutter release for pinpoint focus on the subject on the move.

Multi-mode exposure system: The 645N’s four distinctive exposure modes allow the user to react effortlessly and efficiently to every situation and create the desired visual effect with ease. “Programmed AE” for adjustment-free shooting; “Aperture-Priority AE” to emphasize the depth of field; “Shutter-Priority AE” for sports and action photography; and “Metered Manual” for maximum control over exposure settings.

Sophisticated metering system: The 645N incorporates a newly developed “Dual Six-Segment” multi-pattern metering system. Two sensors positioned at both sides of the viewfinder measure the subject’s lighting condition of two different areas: the wide sensor covers the entire image field, while the narrow sensor monitors the light reaching the central area of the image field. As a result, the 645N can measure the subject’s lighting condition with exceptional accuracy and efficiency. In addition to the Dual Six-segment metering, the 645N also offers the pinpoint “Spot Metering” and conventional “Center-Weighted Metering” modes.

Auto bracketing: With a single shutter release, this function automatically takes three pictures of the same subject in the order of normal, under- and overexposure. The desired exposure level can be easily selected using the auto bracketing lever.

Exposure compensation: The function allows the photographer to make minute exposure adjustment with ease in 1/3 steps within a range of ±3EV.

Memory lock: This function memorizes the subject’s lighting condition for 10 seconds with a single push on the button, allowing the photographer to re-compose the image freely without changing the exposure level on the most important element of the picture.

Interchangeable focusing screens: The 645N incorporates an acclaimed Natural-Bright-Matte focusing screen to provide a sharp, bright viewfinder image. In addition to the standard Center Spot Matte screen, the photographer can also select the AF Split-Image, AF Microprism or Cross-Lined Matte screen, depending on the purpose or application.

On-the-film data recording: To keep accurate track of photographic data, the 645N lets the user imprint valuable data (exposure frame number, exposure mode, shutter speed, aperture, exposure compensation value, metering mode, and lens focal length) at the bottom of the film just outside the image area.

High-speed motor drive: The 645N’s built-in motor drive advances the film at the speed of 2.0 frames per second. Thanks to the high-precision pulse-count film transport mechanism, the spacing between frames is identical and the number of frames which can be taken from one roll of film has been increased from the 645 (16 frames from the 120 film and 33 frames from the 220 film). This motordrive also offers two film advance modes: “Single Advance” to advance one frame for each release of the shutter button and “Consecutive Advance” to successively advance the film as long as the shutter release button is depressed. In addition, the motor drive automatically loads the film and advances it to the first frame, and winds the film into the film holder to avoid accidental exposure during film changes.

Interchangeable film holders: The 645N uses exclusive film holders compatible with those of the 645. So, by carrying several film holders loaded with film, the photographer can save a considerable amount of time for film changes.

Simple-to-operate dial control system: Two large dials located on both sides of the prism housing facilitate swift, mistake-free operation, while other levers and switches are ergonomically positioned for maximum ease of operation.

Large LCD data panel: Located at the camera’s right shoulder, the LCD data panel provides the photographer with useful operational data at a glance in easy-to understand letters, digits and symbols.

Full information viewfinder display: An LCD data panel located at the bottom of the viewfinder indicates a full range of photographic data. Its bar-graph indicator is especially useful for checking exposure status in the Metered Manual mode. The brightness of the indication is automatically adjusted according to the subject’s illumination level.

Depth-of-field preview: This function allows the photographer to check the depth of field before taking a picture, thus making it possible to create the desired visual effect without failure.

Multi-exposure: This function enables the photographer to produce a unique, eye-catching image by making the desired number of exposures on a single frame.

Built-in diopter adjuster: The 645N’s viewfinder eyepiece comes equipped with a built-in diopter adjuster to adjust the viewfinder image for near - and far-sightedness within a range between -3.5 and +1 diopters.

Lithium battery compatibility: The 645N’s battery holder takes six AA-size batteries. In addition to alkaline batteries, lithium batteries, which offer a longer battery life and a stable power supply at low temperatures, can also be used. The Battery Pack 645 is available as an optional accessory to keep batteries warm at freezing temperatures.

Self-timer: The built-in self-timer delays shutter release by 12 seconds, allowing the photographer to become part of memorable pictures. This is also useful for avoiding camera shake in slow-shutter and bulb applications.

New 645 autofocus lenses: For the 645N, Pentax developed five SMC-Pentax FA autofocus lenses to assure fast, stable autofocus operation. These lenses are all treated with Pentax’s original Super-Multi-Coating and incorporate a host of advanced mechanisms to offer outstanding optical performance and assure superb handling in the field. They also feature new autofocus/manual-focus switching mechanisms to improve manual-focus accuracy and efficiency.

Compatibility with conventional 645 lenses and accessories: All existing SMC Pentax-A 645 lenses can be used with the new 645N without any modifications (except for autofocus operation). A wide variety of optional accessories are also available to satisfy the photographer’s need for special applications.

Manufacturer description #2

The Pentax 645N, our latest development in the area of the medium format SLR, promises a superior 6 x 4.5cm result with 120, 220, or 70mm film.

Made possible through our vast experience and technology accumulated over the years, the new autofocus multi-mode 645N assures pin-sharp focus accuracy with AF Spot and AF Wide selection, and the 6-segment multi-pattern metering allows precise exposure control under widely varying conditions. Unsurpassed versatility is assured through the utilizing of a full range of exposure modes (Programmed AE, Aperture-Priority AE and Shutter-Priority AE, Metered Manual and TTL auto flash control), as well as an exposure compensation control and Auto-Bracketing Mode.

With a 645 A- or FA lens attached, the 645N imprints relevant information (frame number, shutter speed, aperture setting, exposure control and auto-bracketing mode).

The Pentax 645N is a professional camera possessing a number of highly sophisticated features: built-in automated film wind, an external LCD information panel and clearly visible LCD information in the viewfinder.


TYPE: TTL autofocus, auto-exposure 6 x 4.5 format SLR camera

FORMAT: 56 x 41.5 mm.

USABLE FILM: 120 roll film (16 exposures) with 120 film holder, 220 roll film (33 exposures) with 220 film holder and 70mm roll film (about 95 exposures) with 70mm film holder.


EXPOSURE MODES: Programmed AE, Aperture-priority AE, Shutter-priority AE, Metered manual, Bulb, TTL flash.

SHUTTER: Electronically-controlled vertical-run cloth focal-plane shutter, Speed range: Auto 1/1000-30 sec. (stepless), Manual 1/1000-4 sec., Bulb.

LENS MOUNT: Pentax 645 AF mount (645 A-mount with AF coupler, lens information contacts).

COMPATIBLE LENS: Pentax 645 AF mount, Pentax 645 A-mount.

AUTOFOCUS SYSTEM: TTL phase-matching multi-(3 points) autofocus system switchable to Spot focusing, AF operational brightness range: EV -1 to 18 (at ISO 100), Focus lock available using shutter release button, Focus Mode: SERVO (predictive AF provided), SINGLE, Manual [MF].

VIEWFINDER: Keplerian telescopic viewfinder with Natural-Bright-Matte focusing screen (Interchangeable focusing screens available), Field of view: 92% vertical and 93% horizontal, 0.76x magnification with 75mm lens at infinity. Diopter: -3.5 to +1.5 diopters, 3-point AF frame, Spot AF frame, Spot AF range.

VIEWFINDER INDICATION: Focus Information: In-focus (Green lamp is lit), front or back focus signals and unable-to-focus indicator (Green lamp blinks), Shutter speed indication, Aperture indication, Flash ready indication is lit, Bar graph (exposure compensation), Auto bracketing indicator, Over or Under exposure indication in Manual Exposure Mode, exposure compensation indication, memory lock indicator.

EXTERNAL LCD PANEL INDICATION: [D] = possible to imprint exposure data; Battery exhaustion warning, Film speed, ISO indication, Film counter.

SELF-TIMER: Electronically-controlled type with delay time of 12 sec. Start by depressing of shutter release button, Operation confirmation: By PCV beep tone. Cancelable after operation.

MIRROR: Instant-return mirror with AF secondary mirror.

FILM LOADING: 120 and 220 films semi-automatically loaded with a start mark, 70mm film automatically loaded.

FILM WINDING: Auto film winding by built-in motor with single/consecutive mode, Approx. 2.0 frames/sec. (consecutive mode).

EXPOSURE METERING: TTL dual six-segment metering, Metering range from EV2 to EV21 at ISO100 with 75mm f2.8 lens, Center-weighted and Spot metering mode can be set.

EXPOSURE COMPENSATION: +/-3EV in 0.3EV step increment.

MULTIPLE EXPOSURE: Via Multi-exposure switch.

AUTO BRACKETING: 1/3EV step increments, 2/3EV step increments, 1EV step increments, Possible to use with exposure compensation.

FLASH SYNC: Via Hot shoe with X-sync. contact with couples with Pentax dedicated auto flashes, X-sync speed at 1/60 sec., Slow shutter speed synchronization possible in Metered Manual Mode, X-sync. socket is provided, ISO range=25-800.

EXPOSURE DATA IMPRINTING: Possible to imprint the exposure data on the outside of the picture frame. Frame number, exposure mode, shutter speed, aperture value, exposure compensation, metering mode and focal length.

POWER SOURCE: Six AA-size 1.5V batteries (Alkaline or Lithium battery), an optional Remote battery pack 645 is attachable with connecting the power cord.

BATTERY EXHAUSTION WARNING: Battery exhaustion symbol is lit (blinking when the shutter is locked; no indication in the viewfinder).

SUPPLIED ACCESSORIES: Body mount cap 645, Rear body cap 645, Release socket cap F, Strap D, Large eye cap 645, and Hot shoe cover Fc.

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Table of contents
Instruction manual
Pentax 645 system cameras

Copyright © 2012-2022 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

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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.