Shutter speed
In photography, shutter speed or exposure time is the length of time when the film or digital sensor inside the camera is exposed to light when a camera's shutter is open when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. 1⁄500 of a second will let half as much light in as 1⁄250. The camera's shutter speed, the lens's aperture, the Film Speed, the scene's luminance together determine the amount of light that reaches the film or sensor. Exposure value is a quantity that accounts for the f-number. Once the sensitivity to light of the recording surface is set in numbers expressed in "ISOs", the light emitted by the scene photographed can be controlled through aperture and shutter-speed to match the film or sensor sensitivity to light; this will achieve a good exposure. Too much light let into the camera results in an overly pale image while too little light will result in an overly dark image. Multiple combinations of shutter speed and f-number can give the same exposure value.
According to exposure value formula, doubling the exposure time doubles the amount of light. Reducing the aperture size at multiples of one over the square root of two lets half as much light into the camera at a predefined scale of f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, so on. For example, f/8 lets 4 times more light into the camera. A shutter speed of 1⁄50 s with an f/4 aperture gives the same exposure value as a 1⁄100 s shutter speed with an f/2.8 aperture, the same exposure value as a 1⁄200 s shutter speed with an f/2 aperture, or 1⁄25 s at f/5.6. In addition to its effect on exposure, the shutter speed changes the way movement appears in photographs. Short shutter speeds can be used to freeze fast-moving subjects, for example at sporting events. Long shutter speeds are used to intentionally blur a moving subject for effect. Short exposure times are sometimes called "fast", long exposure times "slow". Adjustments to the aperture need to be compensated by changes of the shutter speed to keep the same exposure.
In early days of photography, available shutter speeds were not standardized, though a typical sequence might have been 1⁄10 s, 1⁄25 s, 1⁄50 s, 1⁄100 s, 1⁄200 s and 1⁄500 s. Soon this problem resulted in a solution consisting in the adoption of a standardized way of choosing aperture so that each major step doubled or halved the amount of light entering the camera, a standardized 2:1 scale was adopted for shutter speed so that opening one aperture stop and reducing the amount of time of the shutter speed by one step resulted in the identical exposure; the agreed standards for shutter speeds are: With this scale, each increment doubles the amount of light or halves it. Camera shutters include one or two other settings for making long exposures: B keeps the shutter open as long as the shutter release is held. T keeps the shutter open; the ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of the slowest possible shutter speed for a handheld camera.
The rough guide used by most 35 mm photographers is that the slowest shutter speed that can be used without much blur due to camera shake is the shutter speed numerically closest to the lens focal length. For example, for handheld use of a 35 mm camera with a 50 mm normal lens, the closest shutter speed is 1⁄60 s, while for a 200 mm lens it is recommended not to choose shutter speeds below 1⁄200 of a second; this rule can be augmented with knowledge of the intended application for the photograph, an image intended for significant enlargement and closeup viewing would require faster shutter speeds to avoid obvious blur. Through practice and special techniques such as bracing the camera, arms, or body to minimize camera movement, using a monopod or a tripod, slower shutter speeds can be used without blur. If a shutter speed is too slow for hand holding, a camera support a tripod, must be used. Image stabilization on digital cameras or lenses can permit the use of shutter speeds 3–4 stops slower.
Shutter priority refers to a shooting mode used in cameras. It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture; this is sometimes referred to as Shutter Speed Priority Auto Exposure, or TV mode, S mode on Nikons and most other brands. Shutter speed is one of several methods used to control the amount of light recorded by the camera's digital sensor or film, it is used to manipulate the visual effects of the final image. Slower shutter speeds are selected to suggest the movement of an object in a still photograph. Excessively fast shutter speeds can cause a moving subject to appear unnaturally frozen. For instance, a running person may be caught with both feet in the air with all indication of movement lost in the frozen moment; when a slower shutter speed is selected, a longer time passes from the moment the shutter opens till the moment it closes. More time is available for movement in the subject to be recorded by the camera as a blur.
A slower shutter speed will allow the photographer to introd
Metering mode
In photography, the metering mode refers to the way in which a camera determines exposure. Cameras allow the user to select between spot, center-weighted average, or multi-zone metering modes; the different metering modes allow the user to select the most appropriate one for use in a variety of lighting conditions. In complex light situations professional photographers tend to switch to manual mode, rather than depending on a setting determined by the camera. With spot metering, the camera will measure only a small area of the scene. By default this is the centre of the scene; the user can recompose by moving the camera after metering. Certain models support a mode which allows averaging of multiple spot meter readings, some support metering of highlight and shadow areas. Spot metering is not influenced by other areas in the frame, it is used to shoot high contrast scenes. For example, in a backlit situation a rising sun may be behind a person whose face will be much darker than the bright halo around the body and hairline.
Spot metering allows the camera to measure the light reflected from the person's face and expose properly for that, instead of adjusting exposure for the much brighter light around the hairline. With the face properly exposed, the area around the back and hairline will become over-exposed. In many cases spot metering will over or underexpose a portion of the scene, so that the point of interest will be exposed. Another example of the use of spot metering is photographing the moon. Other metering methods will increase overall exposure in an attempt to lighten the dark sky area, resulting in overexposure of the moon. Spot metering gives correct exposure of the moon and underexposes the rest of the scene, dark so the low exposure is not noticeable. Spot metering may be used for theatre photography, where brightly lit actors appear in a darkened auditorium. Spot metering is a method upon. In this system, the meter concentrates on the central 60–80% of the scene; the balance is "feathered" out towards the edges.
This mode of exposure is less influenced by peripheral areas of the scene and is therefore well suited for photographs with subjects or objects of interest in the central part of the image. Some cameras allow the user to adjust the weight/balance of the central portion to the peripheral one. If the camera allows a user to move the focus point off the image center, metering will occur around the new focus location. Although promoted as a feature, center-weighted metering was a consequence of the meter reading from the focusing screen of SLR cameras. Light scatter from the focusing screen and proximity of the meter cell caused less sensitivity at the edges. In this metering mode, the camera uses light information from the entire scene and creates an average for the final exposure setting, giving no weighting to any particular portion of the metered area. In some situations, such as a snowy landscape, this mode will result in underexposure by 2 f-stops or more, because the metering system attempts to darken an excessively bright scene.
This mode meters a larger area than spot metering, is used when bright or dark areas on the edges of the frame would otherwise unduly influence the metering. As in spot metering, some cameras can use variable points for readings or use a fixed point in the centre of the viewfinder; this mode is called matrix, honeycomb, segment metering, or esp metering on some cameras. This metering mode was first introduced by the Nikon FA and was termed Automatic Multi-Pattern metering. On a number of cameras this is standard setting; the camera measures the light intensity in several points in the scene and combines the results to find the setting for the best exposure. The method of calculatation can be different from camera to camera; the actual number of zones used varies from several to over a thousand. The design concept behind multi-zone is to reduce the need to use exposure compensation. Many manufacturers keep their exact calculation methods confidential as proprietary information. A number of factors are taken into consideration, including: autofocus point, distance to subject, areas in or out of focus, colours/hues of the scene, backlighting.
Multi-zone tends to bias its exposure towards the autofocus point, thus ensuring that the point of interest has been exposed for properly. A database of thousands of exposures may be pre-stored in the camera, the processor can use that information to determine what is being photographed; some cameras allow the option of locking exposure. In other cameras the AF point is not used for exposure calculation, in such cases it is common for metering to default to a central point in the viewfinder, using a pattern based on that area. There is considerable variation among different manufacturers how multi-zone metering is implemented–even in the model range of the same brand–and how much priority is given to the AF point itself; some "Scene" modes, such as sunset and night exposures often affect the calculations of this metering pattern. Clipping is reduced by using a high resolution metering sensor and analyzing each area for washed-out highlights or underexposed shadows. Although there are some similarities with multi-zone, matrix, or evaluative metering, this mode uses a high-resolution sensor for detailed detection and gives more weight to reduce clipping.
Feathering Vignetting Understanding Metering and Metering Modes Metering Modes and How Your Camera Meter Works Highlight-Weighted Metering: Technical Details and Use Nikon
Through-the-lens metering
In photography, through-the-lens metering refers to a feature of cameras whereby the intensity of light reflected from the scene is measured through the lens. In some cameras various TTL metering modes can be selected; this information can be used to set the optimal film or image sensor exposure, it can be used to control the amount of light emitted by a flash unit connected to the camera. Through-the-lens metering is most associated with single-lens reflex cameras. In most film and digital SLRs, the light sensor for exposure metering are incorporated into the pentaprism or pentamirror, the mechanism by which a SLR allows the viewfinder to see directly through the lens; as the mirror is flipped up, no light can reach there during exposure, the necessary amount of exposure needs to be determined before the actual exposure. These light sensors could traditionally be used for ambient light TTL metering only. In newer SLRs as well as in all DSLRs, they can be utilized for preflash TTL metering, where the metering is carried out before the mirror flips up using a small preflash of known intensity and the necessary amount of flash light is extrapolated from the reflected flash light measured by the metering cells in the roof of the camera and is applied during the exposure without any possible real-time feedback.
There were a few sophisticated film SLRs including the Olympus OM-2, the Pentax LX, the Nikon F3, the Minolta 9000, where metering cells located at the bottom of the mirror box were used for ambient light metering, depending on model either instead or in addition to metering cells in the roof of the camera. Depending on model, the light was reflected down there either by a secondary mirror behind the half-transparent main mirror, a special reflective coating of the first shutter curtain, the surface of the film itself, or combinations thereof. One of the advantages of this approach is that the measuring result requires no adjustments when changing focusing screens or viewfinders; some of the cameras using this configuration are immune against measurement errors caused by light reaching the metering cells at larger angles, for example with shift/tilt lenses. Metering cells located at the bottom of the mirror box using light reflected off the film are used in all film SLRs supporting the classical form of real-time TTL flash metering.
Some early Pentax DSLRs could use this same configuration for TTL flash metering as well, but since the reflectance properties of image sensors differ from those of film, this method proved to be unreliable in practice. Therefore, digital SLR cameras don't support any real-time TTL flash metering and must use preflash metering instead; the ambient and flash light metering is carried out by a metering module located in the roof of the camera. Digital SLRs supporting live view or video will use the read out of the image sensor itself for exposure metering in these modes; this applies to Sony's SLT digital cameras, which use the image sensor for exposure metering all the time. Up to the time of this writing, no digital SLR or SLT camera on the market supported any form of real-time TTL flash metering using the image sensor. However, it can be expected that such methods will be introduced as image sensor technology progresses, given the advantages of metering with real-time feedback and without preflash.
TTL metering systems have been incorporated into other types of cameras as well. Most digital "point-and-shoot cameras" use TTL metering, performed by the imaging sensor itself. In many advanced modern cameras multiple'segments' are used to acquire the amount of light in different places of the picture. Depending on the mode the photographer has selected, this information is used to set the exposure. With a simple spot meter, a single spot on the picture is selected; the camera sets the exposure. On some modern SLR systems the spot metering area or zone can be coupled to the actual focusing area selected offering more flexibility and less need to use exposure lock systems. With multiple segment metering, the values of the different segments are combined and weighted to set the correct exposure. Implementations of these metering modes vary between cameras and manufacturers, making it difficult to predict how a scene will be exposed when switching cameras. In the 1970s Olympus marketed the OM-2 camera.
In OTF metering used by Olympus, metering was performed in one of two ways — or a combination of both — depending upon the shutter speed in use. In the OM-2's Auto Dynamic Metering system the first shutter curtain had the lens-facing side coated with a computer generated pattern of white blocks to emulate an average scene; as the mirror flipped-up the metering cell in the base of the mirror box measured the light reflected from the subject bouncing off this pattern of blocks. The timing of the release of the second curtain was adjusted in real time during the actual exposure; as the shutter speed increased, the actual light reflecting off the film surface was measured and the timing of the second curtain's release adjusted accordingly. This gave cameras equipped with this system the ability to adjust to changes in lighting during the actual exposure, useful for specialist applications such as photomicrography and astronomical photography. Leica used a variation of this system, as did Pentax with their Integrated Direct Metering in the LX camera.
A variation of this "OTF" system was used on early
Pentax K1000
The Pentax K1000 is an interchangeable lens, 35 mm film, single-lens reflex camera, manufactured by Asahi Optical Co. Ltd. from 1976 to 1997 in Japan. The K1000's extraordinary longevity makes it a significant camera; the K1000's inexpensive simplicity was a great virtue and earned it an unrivaled popularity as a basic but sturdy workhorse. The Pentax K1000 sold over three million units; the K1000, introduced in 1976, is the simplest member of Asahi Optical's Pentax K-series 35mm SLRs. The other members are the Pentax K2, KM, KX, introduced in 1975, the K2 DMD of 1976. All have the same basic body design, but with differing feature levels and controls; the K1000 was the KM with the self-timer, depth of field pre-view and some other features removed to save cost. It uses a horizontal travel, rubberized silk cloth focal plane shutter with a speed range of 1/1000 second to 1 second, along with Bulb and a flash X-sync of 1/60 second, it is 91.4 millimetres tall, 143 mm wide, 48 mm deep, weighs 620 grams.
The body was finished in black leather with chrome trim only, although early production Pentax K1000 SE bodies had brown leather with chrome trim. The introductory US list price for the K1000 body with SMC Pentax 55 mm f/2 lens was $299.50. In 1983, a K1000 with SMC Pentax-M 50 mm f/2 lens listed for $220; the body remained there until discontinued. Note that SLRs sold for 30 to 40 percent below list price; the K1000 is an almost-all metal, mechanically controlled, manual-focus SLR with manual-exposure control. It is operable without batteries. Batteries are only required for the light metering information in the viewfinder; this consists of a centre-the-needle exposure control system using a galvanometer needle pointer moving between vertically arranged +/– over/underexposure markers to indicate the readings of the built-in full-scene averaging, cadmium sulfide battery light meter versus the actual camera settings. The meter does not have an on/off switch and the lens cap must be attached to the lens to prevent draining the K1000's battery when it is not in use.
The K1000 comes with its own black camera strap out of the box. Conventional for the time, there is a film advance lever on the right and a rewind crank on the left on the top plate. There is a basic hot shoe for an electronic flash unit, a PC flash lead socket, of X type synchronisation. There are no flash dedication features; the viewfinder has a focusing screen with a microprism spot focusing aid. The Pentax K1000 SE substitutes a split image rangefinder plus microprism collar focusing screen; the K1000 SE is otherwise identical to the regular K1000, except that the SE's from the first two years of production in late 1977 to 1978 used a Black Diamond patterned leatherette for 2500 units and a brown leather instead of black after that on the early SE models. The K1000 has a Pentax K bayonet mount, it was sold with the budget SMC Pentax 50 mm f/2 lens, it accepts any other manual focus lens with the K mount. This includes SMC Pentax-M and SMC Pentax-A types. In addition all lenses with the Pentax K-AF and K-AF2 autofocus lens mounts work in manual focus mode.
The exceptions are Pentax's newest SMC-Pentax FA J and SMC-Pentax DA types which lack an aperture control ring, K mount lenses designed for APS-C cameras. There are adaptors to allow older screw mount lenses to be used on K mount cameras. In all, there are vast numbers of Pentax and third party lenses that can be used with the K1000 and other K mount camera bodies; as a budget camera, the K1000 has fewer features than other mid-1970s SLRs. In particular it lacks a self timer; the sparse information in the viewfinder can make taking photos a little ponderous, as the camera might need to be removed from the eye to check settings, on top of which the meter is slow to respond by 1976 standards. The K1000 is a manual camera, requiring more expertise in use than some of its contemporaries; the K1000 gained popularity because of its low cost, for the reputation it won for ruggedness and reliability. Its spartan lack of certain features are regarded by some as a good feature in itself. In addition, for many years it was the camera recommended or mandated to students starting art or photography courses, because its manual controls forced users to learn about exposure - after better manual cameras came along.
Today, good used versions fetch higher prices than its more costly and better featured K Series siblings because those others, made in far fewer numbers, are overlooked or have been forgotten. In 1975, Asahi Optical replaced its Spotmatic series of 35mm SLR cameras with three cameras of the K-series, the Pentax K2, KM and KX, they continued the successful Spotmatics' general style and handling but with the use of a new bayonet mount, the K Mount, in place of the previous M42 screw mount. The KM in particular was otherwise identical to the old Spotmatic F model apart from some top plate styling; the top of the range K2 had an aperture priority auto and manual modes, while the KX and KM were metered manual only, but the K2 and KX were more technically advanced than the KM. A range of SMC Pentax K mount le
A Hard Day's Night (film)
A Hard Day's Night is a 1964 British musical comedy film directed by Richard Lester and starring the Beatles—John Lennon, Paul McCartney, George Harrison, Ringo Starr—during the height of Beatlemania. It was written by Alun Owen and released by United Artists; the film portrays 36 hours in the lives of the group. The film was a critical success. Forty years after its release, Time magazine rated it as one of the all-time great 100 films. In 1997, British critic Leslie Halliwell described it as a "comic fantasia with music; the film is credited as being one of the most influential of all musical films, inspiring numerous spy films, the Monkees' television show and pop music videos. In 1999, the British Film Institute ranked it the 88th greatest British film of the 20th century. Bound for a London show from Liverpool, the Beatles escape a horde of fans. Once they are aboard the train and trying to relax, various interruptions test their patience: after a dalliance with a female passenger, Paul's grandfather is confined to the guard's van and the four lads join him there to keep him company.
John Lennon, Paul McCartney, George Harrison and Ringo Starr play a card game, entertaining some schoolgirls before arriving at their desired destination. Upon arrival in London, the Beatles are driven to a hotel, they are tasked to answer numerous letters and fan mail in their hotel room but instead they sneak out to party. After being caught by their manager Norm, they return to find out that Paul's grandfather John went to the casino. After causing minor trouble at the casino, the group is taken to the theatre where their performance is to be televised. After rehearsals, the boys leave through a fire escape and dance around a field but are forced to leave by the owner of the property. On their way back to the theatre, they are separated when a woman named Millie recognises John as someone famous but cannot recall who he is. George is mistaken for an actor auditioning for a television show featuring a trend setter hostess; the boys all return to rehearse another song and after goofing around backstage, they play another song to impress the makeup artists.
While waiting to perform, Ringo is forced to look after Paul's grandfather and decides to spend some time alone reading a book. Paul's grandfather, a "villain, a real mixer", convinces him to go outside to experience life rather than reading books. Ringo goes off by himself, he tries to have a quiet drink in a pub, takes pictures, walks alongside a canal, rides a bicycle along a railway station platform. While the rest of the band frantically and unsuccessfully attempts to find Ringo, he is arrested for acting in a suspicious manner. Paul's grandfather joins him shortly after attempting to sell photographs wherein he forged the boys' signatures. Paul's grandfather makes a run for it and tells the rest of the band where Ringo is; the boys all go to the station to rescue Ringo but end up running away from the police back to the theatre and the concert goes ahead as planned. After the concert, the band is taken away from the hordes of fans via helicopter; the screenplay was written by Alun Owen, chosen because the Beatles were familiar with his play No Trams to Lime Street, he had shown an aptitude for Liverpudlian dialogue.
McCartney commented, "Alun hung around with us and was careful to try and put words in our mouths that he might've heard us speak, so I thought he did a good script." Owen spent several days with the group, who told him their lives were like "a train and a room and a car and a room and a room and a room". Owen wrote the script from the viewpoint that the Beatles had become prisoners of their own fame, their schedule of performances and studio work having become punishing; the script comments cheekily on the Beatles' fame. For instance, at one point a fan, played by Anna Quayle recognises John Lennon, though she does not mention Lennon's name, saying only "you are...". He demurs, saying his face is not quite right for "him", initiating a surreal dialogue ending with the fan agreeing that Lennon doesn't "look like him at all", Lennon saying to himself that "she looks more like him than I do". Other dialogue is derived from actual interviews with the Beatles; when Ringo is asked if he's a mod or a rocker, he replies: "Uh, no, I'm a mocker", a line derived from a joke he made on the TV show Ready Steady Go!.
The frequent reference to McCartney's grandfather as a "clean old man" sets up a contrast with the stock description of Brambell's character, Albert Steptoe in Steptoe and Son, as a "dirty old man". Audiences responded to the Beatles' brash social impudence. Director Richard Lester said, "The general aim of the film was to present what was becoming a social phenomenon in this country. Anarchy is too strong a word, but the quality of confidence that the boys exuded! Confidence that they could dress as they liked, speak as they liked, talk to the Queen as they liked, talk to the people on the train who'fought the war for them' as they liked.... Still based on privilege—privilege by schooling, privilege by birth, privilege by accent, privilege by speech; the Beatles were the first people to attack this
Pentax K-mount
The Pentax K-mount, sometimes referred to as the "PK-mount", is a bayonet lens mount standard for mounting interchangeable photographic lenses to 35 mm single-lens reflex cameras. It was created by Pentax in 1975, has since been used by all Pentax 35 mm and digital SLRs and the MILC Pentax K-01. A number of other manufacturers have produced many K-mount lenses and K-mount cameras; the Pentax K-mount has undergone a number of evolutions over the years as new functionality has been added. In general, the term K-mount may refer to all its variations. Designed by Zeiss for an alliance with Pentax, it was intended to be a common lens mount for a proposed series of cameras and lenses. However, the plan failed to work out and the two firms parted company amicably, but Pentax retained the lens mount and at least one Zeiss lens design for its own use; the original K-mount is a simple bayonet connection with three tabs. It was introduced with the K series of cameras; the lens is locked into the camera with an approx.
70° clockwise turn. The only linkage with the camera involves the aperture. A slot between two of the bayonet tabs on the lens allows the stop-down coupler from the camera to sense the aperture setting on the lens and adjust the light meter display accordingly. Opposite this is the diaphragm release from the lens which extends into the camera body and holds open the spring-loaded diaphragm of the lens; when setting up a shot this keeps the diaphragm open. When the shutter is released, so is this lever, it allows the diaphragm to close to the desired setting while the film is being exposed, opens it again after the shutter closes. Both of these linkages are arranged so that they are aligned and spring-loaded by the act of inserting the lens and turning it until it locks. Bodies equipped with the original K-mount include the K series, the M series except the ME F, the LX. Lenses that support it include those labelled'SMC Pentax','SMC Pentax-M' and'SMC Pentax-A'; these K-mount bodies cannot use lenses that lack an aperture ring, such as FAJ or DA.
K-mount lenses can be used on all Pentax bodies, but are restricted to stopped down mode when used with "crippled" KAF-mount bodies. The KF-mount was Pentax's first attempt at an autofocus system; this autofocus system used sensors in a motor in the lens. The two were connected via five new electrical contacts on the bayonet mount itself. One permitted the lens to turn on the camera's metering and focus sensors, two focused the lens and two appear to have been unused and may have been reserved for future functionality; the KF-mount was a failure. Only one camera and one lens used this mount, the Pentax ME F and SMC Pentax-AF 35-70/2.8. The lens was somewhat large and cumbersome since it had to enclose both the focusing motor and batteries to power it. KF and the ME-F are similar in many ways to the system used by Canon in the ill-fated Canon T80, introduced several years later; the ME F can use all Pentax K-mount lenses. The 35–70 mm lens can be used on all other Pentax K-mount bodies in manual focus mode, but it must be used stopped down on "crippled" KAF bodies.
The KA-mount is derived from the original K-mount. It allows the lens's aperture to be set by the body, thus permits shutter priority and program auto exposure modes, it was introduced in 1983, is supported by A-series and P-series bodies. It is backward-compatible with the original K-mount; the aperture on the lens is set from the body by the same stop-down lever found on the original K-mount, but on KA-lenses this lever is proportional to the area of the aperture opening, rather than the diameter as on previous lenses. This allows the body to set a specific aperture, since the relationship to F stops is linear; the lenses add an ` A' setting on the aperture dial. Other, numeric settings are used for manual aperture modes -- full manual mode. Six electrical contacts are added to the bayonet ring. One is recessed and allows the lens to indicate whether the aperture ring is set at'A' or not. If it is, a pin on the lens extends and makes contact, while if the lens is at any other setting the pin is retracted and does not make contact.
The other five contacts are used to encode the lens's aperture range. Each contact on the lens is either conducting or non-conducting, providing a binary 1 or 0, respectively. Two contacts encode the lens's minimum aperture—f/16, f/22, f/32 or f/45; the other three contacts encode the lens's maximum aperture. The KAF-mount was Pentax's much improved attempt at adding auto-focus to lenses, it adds a small drive shaft to the KA-mount. This makes the lenses less bulky than the earlier KF-mount, which had both a motor and batteries inside the lens, it adds a seventh electrical contact, this one carrying digital information from the lens to the camera. It carries the following information: focal length, distance to the subject, exact absolute f-stop value, lens size; this information is used to make better exposure decisions, along with the multi-segmented metering, introduced in cameras using the KAF-mount. The MZ-30/ZX-30, MZ-50/ZX-50, MZ-60/ZX-60, the *ist series and the K100D/K110D lack the mechanical stop-down coupler/indicator.
In these cameras – in aperture priority mode – the aperture is set by
Media related to Pentax Spotmatic at Wikimedia Commons