Asahi Pentax K2

35mm MF film SLR camera

Specification

Production details
Announced:June 1975
System: Pentax K (1975)
Imaging plane
Maximum format:35mm full frame
Mount and Flange focal distance:Pentax K [45.5mm]
Imaging plane:36 × 24mm film
Shutter
Type:Focal-plane
Model:Electronically controlled
Speeds:8 - 1/1000 + B
Exposure
Exposure metering:Through-the-lens (TTL)
Exposure modes:Aperture-priority Auto
Manual
Physical characteristics
Weight:680g
Dimensions:144x92x57mm

Manufacturer description #1

TYPE: 35mm SLR with through-the-lens light meter and vertical electronic focal-plane shutter. Exposure control fully automatic or manual

FILM AND PICTURE SIZE: 35mm film. 24mm x 36mm

SHUTTER: Vertical run, metal focal-plane shutter. Shutter button lock provided. Automatic electronic shutter: stepless between 8 and 1/1000 sec. Manual electronic shutter: 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000 sec. Manual mechanical shutter: B, 1/125 sec. (when battery is dead)

FLASH SYNCHRONIZATION: X contact hot shoe for cordless flash connection. FP + X contacts for conventional flash cord connection. X synchronization at 1/125 sec.

SELF-TIMER: Built-in self-timer with interrupt function. 5-9 sec. delay after tripping shutter release

VIEWFINDER: Pentaprism finder with cross-microprism or split-image focusing screen. 0.88x magnification with 50mm lenses (life-size with 55mm lens). 95% field of view. Dioptry -0.8. "Incorrect exposure range" indicator

FOCUSING: Turn focusing ring until viewfinder image comes into focus

REFLEX MIRROR: Swing-up-and-back, instant-return type, with mirror lock-up lever, and special shock absorbers for minimum vibration

FILM ADVANCE: Single-stroke wind lever. 25° pre-advance and 130° advance angles

EXPOSURE COUNTER: Automatic re-set

FILM REWIND: Rapid-rewind crank lifts clear of body

LENS MOUNT: Pentax bayonet mount. Rotation: 65°

EXPOSURE METER: Silicon Photo Diode-activated, aperture-preferred, through-the-lens meter measures central portion of ground glass at full lens aperture. Match needles for correct exposure on manual. Couples directly to shutter, aperture and film speed settings. Shutter speed and auto/manual setting visible in viewfinder for exposure doublecheck

EXPOSURE CONTROL: Exposure factor control dial: 4x, 2x, 1x, 1/2x, 1/4x for specific exposure control

POWER SOURCE: Two 1.5V silver oxide batteries (Eveready S76E or Mallory MS76H)

METER SWITCH: Meter is ON when shutter button is depressed halfway. Also, when film wind lever is at its pre-advance angle and shutter button is depressed halfway, meter stays ON. Battery check button and lamp provided

Manufacturer description #2

The K2 is the finest, fully-automatic electronic exposure SLR camera in the world. The Seiko MF shutter (a compact, metal focal-plane shutter consisting of 5 fan-like leaves) has been created especially for the K2. The K2 offers 2 exposure determination systems: fully-automatic or match-needle operation. Either system can be used at speeds from 1/1000 sec. to 8 sec. From its new shutter to its new exterior finish, the K2 makes the most of its extremely advanced design in every situation, under practically any conditions.

  • Automatic stepless shutter speeds from 8 seconds to 1/ 1000 second.
  • A full range of manual electronic shutter speeds from 1/1000 to 8 second, plus B.
  • New ten bladed vertical running metal shutter.
  • Electronic flash sync at 1/125 second.
  • Fast response silicon photo diode adjusts quickly to abrupt light changes.
  • Mirror lock-up switch to minimize vibrations.
  • 4x to 1/4x exposure factor dial to compensate for difficult lighting situations.
  • Human engineflred for surer, easier and faster handling.
  • Over 30 matching Pentax bayonet lenses with sure grip focusing ring and improved Super-MuIti-Coating.
  • Silver coated pentaprism and a larger mirror mean a brighter viewfinder with no mirror cut-off when using telephoto lenses.
  • A complete system of accessories for every photographic situation.
  • 5.7" wide, 3.6" high and 3.7" deep with the 50mm SMC Pentax f/1.4 lens.
  • The body only is a light 24.2 ozs., with the 50mm f/1.4 lens 33.7 ozs.
  • Center weighted metering.
  • 8-6400 ASA range to handle today's films.
  • Automatic metering for fast action, plus match needle for manual metering.
  • Depth-of-field preview.

Manufacturer description #3

The new Asahi Pentax K Series - the first Pentax system based on the long-awaited K bayonet mount. Foolproof, handy, sure, the K bayonet mount is a "first" that was well worth waiting for. And the new mount is not all that's new about the Pentax K Series. By achieving the highest standards of electronic, optical and mechanical engineering, the new 35mm SLR K Series offers far greater possibilities for all levels of photographic skills.

From now on, there will be three Pentax series available simultaneously: the S Series based on the conventional screw mount, the 6x7 ideal-format system, and the new K Series.

The new Pentax K Series consists of three 35mm SLR models: the K2, the KX and the KM.

The K2 is the cream of the K Series. It is the newest fully-automatic exposure SLR camera and incorporates the unique, vertical-drop Seiko MF (Metal Focal-plane) shutter. A wide range of shutter speeds - 1/1000 to 8 sec. - is available, on either automatic or manual setting.

The new Pentax KX is a through-the-lens metering SLR with a brighter viewfinder to give you complete information. A convenient system of matching needles is located on the right hand side of the viewfinder, and the selected speed and aperture are always visible within the viewfinder.

The Pentax KM is essentially the Spotmatic F camera (the world's most popular fine camera), updated and improved with the new K bayonet mount.

A second part of the new K Series is the brand new line of interchangeable lenses - SMC Pentax lenses. In addition to being equipped with the new K bayonet mount, these new lenses have Super-Multi-Coating on many more glass surfaces, including some which are not exposed to the air. This makes for truer color reproduction and virtually eliminates ghost and flare. Standard focal length SMC Pentax lenses are: the 50mm f/1.4, the 55mm f/1.8 and the new 50mm f/1.2 - the first lens of this type the world has ever seen.

New K Series lenses are uniquely easy to mount. Less than a quarter of a turn does it all - even couples the automatic diaphragm elements and the open-aperture metering elements. And thanks to a raised bump on the lens, SMC Pentax lenses can be mounted with ease, even in the dark.

Four years ago, Asahi Pentax pioneered the application of Super-Multi-Coating to photographic lenses. Since then, the benefits have become universally recognized: up to 99.8% of all available light is directed to the film plane; color reproduction is truer; clarity and brightness are hightened; ghost and flare are virtually eliminated, etc. It's no wonder Super-Multi-Coated lenses are highly valued by photographers around the world!

Even since we started it, we have been making Super-Multi-Coated lenses under the name SMC Takumar. Now that these lenses have been upgraded - with multi-coatings applied to many glass surfaces which previously were only single-coated, we have also given them a new name: SMC Pentax lenses. SMC Pentax interchangeable lenses - even better light transmission, along with the new K bayonet mount.

Because the Pentax K bayonet mount is such an important feature of the new K Series, it deserves a bit more attention.

  1. Less than a quarter turn locks it on. No other mount offers such ease of interchangeability. With a twist of only 65°, the lens is securely mounted, with both the automatic diaphragm elements and the open-aperture metering elements firmly coupled simultaneously.
  2. Imaginatively designed mounting indicators. Simply by matching up the red dots - one each on the lens and the body - mounting can be done easily. Even in the dark, just by matching up the raised bump on the lens barrel with the lens release lever, lenses can be mounted by touch alone.
  3. Exact placement of lever makes for safe, accurate interchanging of lenses. Lenses can be changed safely and easily by holding the camera upright, unlocking the lens by pushing the lever with the thumb, and then turning the lens barrel. Human engineering was the guideline for the positioning of all K Series handling parts.
  4. Inner mount diameter is a wide 45mm. To accomodate faster lenses, the inner diameter of the K mount is a full 45mm. For added brightness also, a 50mm f/1.2 lens is being offered for the first time as a standard focal length lens.
  5. Using conventional screw-mount lenses. Use of the Mount Adaptor K is an inexpensive way of adapting SMC Takumar screw-mount lenses to the new K bayonet mount. This adaptor plays the role of "liason bridge". Because the distance from the K mount to the film plane is 45.5mm, the same as for the S Series, the adaptor has been designed so that coupling takes place in the inside part of the bayonet mount. When using this adaptor, all focusing, up to infinity, is possible. However, apertures must be set manually, and open-aperture metering lenses require stop-down metering.
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35mm full frame

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

Travellers' choice

Note

Among autofocus lenses designed for 35mm full-frame mirrorless cameras only. Speed of standard and telephoto lenses is taken into account.

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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

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),

where:

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

Mount

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.

Speed

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.

Electromagnetic diaphragm control system

Provides highly accurate diaphragm control and stable auto exposure performance during continuous shooting.

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.

Weight

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.

Filters

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

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.