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86-536: As with other Pentax DSLRs, the *ist DS uses the Pentax KAF bayonet mount and can use older lenses using the KA-mount without limitations. Original K mount lenses and, with adapter also M42 screw-mount lenses, can be used in manual mode by selecting a menu option. Centre-weighted metering, aperture priority and focus indication are maintained, even with adapter mounted lenses. When using non-auto aperture lenses,

172-402: A binary 1 or 0, respectively. Two contacts encode the lens's minimum aperture— f /16 , f /22 , f /32 or f /45 ; although no Pentax K-mount lens has ever had an f /16 minimum aperture, OEM lenses often have. The other three contacts encode the lens's maximum aperture; their meaning is dependent on the minimum aperture indicated by the lens. (There are at least 2 newer lenses that have

258-489: A camera based on their previous development at photokina , named Correfot, and in 1978 they displayed an SLR camera with fully operational autofocus. The first mass-produced autofocus camera was the Konica C35 AF , a simple point and shoot model released in 1977. The Polaroid SX-70 Sonar OneStep was the first autofocus single-lens reflex camera , released in 1978. The Pentax ME-F , which used focus sensors in

344-455: A certain degree of illumination to the subject (whether natural or otherwise), while active systems may focus correctly even in total darkness when necessary. Some cameras and external flash units have a special low-level illumination mode (usually orange/red light) which can be activated during auto-focus operation to allow the camera to focus. A method variously referred to as trap focus , focus trap , or catch-in-focus uses autofocus to take

430-415: A display instead of the motor; the adjustment of the optical system has to be done manually until indication. Autofocus methods are distinguished as active , passive or hybrid types. Autofocus systems rely on one or more sensors to determine correct focus. Some AF systems rely on a single sensor, while others use an array of sensors. Most modern SLR cameras use through-the-lens optical sensors, with

516-551: A few "high-precision" focus points with an additional set of prisms and sensors; they are only active with " fast lenses " with certain geometrical apertures (typically f-number 2.8 and faster). Extended precision comes from the wider effective measurement base of the "range finder" Some modern sensors (for example one in Librem 5 ) include about 2% phase detection pixels on the chip. With suitable software support, that enables phase detection auto focus. Contrast-detection autofocus

602-515: A few dozen wide), some modern cameras ( Canon EOS-1V , Canon EOS-1D , Nikon D2X ) feature TTL area SIR sensors that are rectangular in shape and provide two-dimensional intensity patterns for a finer-grain analysis. Cross-type focus points have a pair of sensors oriented at 90° to one another, although one sensor typically requires a larger aperture to operate than the other. Some cameras ( Minolta 7 , Canon EOS-1V , 1D , 30D / 40D , Pentax K-1 , Sony DSLR-A700 , DSLR-A850 , DSLR-A900 ) also have

688-412: A hybrid system is the combination of passive phase-detection auto-focus and passive contrast auto-focus, sometimes assisted by active methods, as both methods need some visible contrast to work with. Under their operational conditions, phase-detection auto-focusing is very fast, since the measurement method provides both information, the amount of offset and the direction, so that the focusing motor can move

774-423: A laser or LED light to the subject and calculating the distance based on the time it takes for the light to travel to the subject and back. This technique is sometimes called laser autofocus , and is present in many mobile phone models from several vendors. It is also present in industrial and medical devices. An exception to the two-step approach is the mechanical autofocus provided in some enlargers, which adjust

860-523: A lens originally intended for Leica Rangefinder cameras is used, focusing is limited to about 10 cm. However, some SLR lenses were made in LTM 39 mount, mostly by KMZ for use in the early Zenit SLRs which had LT 39 mounts. These "Zenit" TM 39 lenses will focus properly. Or these lenses can be used in conjunction with the M42 to LTM 39 adapter. Adaptors can be found to allow use of a non-Leica 39 mm mount into

946-535: A loss of contrast gives no indication of the direction of motion towards or away from the camera. Contrast-detect autofocus is a common method in digital cameras that lack shutters and reflex mirrors. Most DSLRs use this method (or a hybrid of both contrast and phase-detection autofocus) when focusing in their live-view modes. A notable exception is Canon digital cameras with Dual Pixel CMOS AF. Mirrorless interchangeable-lens cameras typically used contrast-measurement autofocus, although phase detection has become

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1032-401: A mechanical stop-down coupler/indicator and thus can only use stop-down metering on pre-A lenses. The K A2 is identical to K AF , but lacks the autofocus drive shaft. Another way of looking at it is that it adds the seventh contact for digital information to the K A -mount. The K AF3 -mount is used on Pentax lenses that solely rely on SDM or DC autofocus motors. It is identical to

1118-412: A minimum aperture of only f/16: HD D FA 85mm F1.4 and HD D FA* 50mm F1.4. https://www.pentaxforums.com/lensreviews/hd-pentax-d-fa-85mm-f14-sdm-aw.html and https://www.pentaxforums.com/lensreviews/hd-pentax-d-fa-50mm-f14-sdm-aw.html ) The K AF -mount was Pentax's second and much improved attempt at adding auto-focus to lenses. It adds a small drive shaft to the K A -mount, allowing the body to adjust

1204-959: A modern-day cult reputation, including the (Pentax) Asahi Takumar range. Some manufacturers, including Carl Zeiss AG , still make lenses in the M42-mount. K-mount cameras have a suitable flange focal distance (45.46 mm) to adapt old M42 lenses without any optical correction or loss of infinity focus/changed close focus distance. Other SLRs with a short flange-focal distance can accept M42 lenses as well: Canon EF-mount (44.00 mm), Sony and (Konica) Minolta A-mount (44.50 mm), Sigma (44 mm), Olympus 4/3rd (38.67 mm), and many more, but notably not Nikon F-mount (46.5 mm). Optically corrected adapter to use Nikon AIS AI lenses on K-mount. Adapter for Voigtländer Bessamatic and Voigtländer Ultramatic lenses, Kodak Retina Reflex , or Kodak Retina IIIs lenses. There are some Petri adapters to K-mount but they do not allow to infinity focus due to

1290-730: A number of lenses for the K-mount through its sales network. These lenses were in fact made by Sigma in Japan. The "real" 35 mm East German made Carl Zeiss Jena Lenses were available at the same time but only in Praktica B-mount. Carl Zeiss is one of the most prestigious names on the photographic world; it re-launched its line of lenses for the K-mount in 2008, mainly due to the growing popularity of both Pentax and Samsung digital SLRs . Carl Zeiss announced in September 2010 that

1376-529: A press of the AE-L button with the camera in manual mode will meter the scene and set the shutter speed. Some non-Pentax K-mount lenses have been reported not to mount on the camera, because a plate protecting the aperture stop-down lever is slightly deeper. Along with the other D-series Pentax DSLRs, the Pentax *ist DS, Pentax *ist DS2, and Pentax *ist D have TTL-mode (not only P-TTL) for external flash. This allows

1462-436: A problem, unless the window is stained. Accuracy of active autofocus systems is often considerably less than that of passive systems. Active systems may also fail to focus a subject that is very close to the camera (e.g., macro photography ). Passive systems may not find focus when the contrast is low, notably on large single-colored surfaces (walls, blue sky, etc.) or in low-light conditions. Passive systems are dependent on

1548-487: A recent firmware update the original K3 can use the new mount. All digital K-mount Pentax SLR bodies as well as some lower-end film cameras lack the ability to read the position of the aperture simulator. This means that lenses that lack the lens information contacts introduced with the K A -mount (Pentax K- and M-series lenses as well as some third-party products) do not support open-aperture metering on these bodies. Instead, stop-down metering must be carried out by pushing

1634-480: A separate sensor array providing light metering , although the latter can be programmed to prioritize its metering to the same area as one or more of the AF sensors. Through-the-lens optical autofocusing is usually speedier and more precise than manual focus with an ordinary viewfinder, although more precise manual focus can be achieved with special accessories such as focusing magnifiers. Autofocus accuracy within 1/3 of

1720-510: A shot when a subject moves into the focal plane (at the relevant focal point); this can be used to get a focused shot of a rapidly moving object, particularly in sports or wildlife photography , or alternatively to set a "trap" so that a shot can automatically be taken without a person present. This is done by using AF to detect but not set focus – using manual focus to set focus (or switching to manual after focus has been set) but then using focus priority to detect focus and only release

1806-528: Is a trade mark of Ukrainian lens manufacturer Arsenal, Kiev. Beroflex seems to have been a German commercial firm of photographic lenses;information is scarce yet but it appears that it designed lenses made overseas by Japanese companies like Soligor . Carl Braun Camera-Werk of Nuremberg, Germany, or Braun, as it was more commonly called, was founded as an optical production house. It is best known for its 35mm film cameras named Paxette, and for slide projectors named Paximat. Carl Zeiss of East Germany marketed

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1892-409: Is achieved by dividing the incoming light into pairs of images and comparing them. Through-the-lens secondary image registration (TTL SIR) passive phase detection is often used in film and digital SLR cameras . The system uses a beam splitter (implemented as a small semi-transparent area of the main reflex mirror, coupled with a small secondary mirror) to direct light to an AF sensor at the bottom of

1978-425: Is achieved by measuring contrast (vision) within a sensor field through the lens . The intensity difference between adjacent pixels of the sensor naturally increases with correct image focus. The optical system can thereby be adjusted until the maximal contrast is detected. In this method, AF does not involve actual distance measurement at all. This creates significant challenges when tracking moving subjects , since

2064-445: Is compatible with all other K-mount cameras and lenses when in manual or aperture-priority exposure modes, however the extra pin needs to be removed for safe use on autofocus Pentax cameras, as it can otherwise become locked within the autofocus shaft. Lenses locked to the camera body this way are difficult to remove and may require complete dismantling. Adaptors can be found to allow use of lenses with Leica M39 thread (screw) mount. If

2150-416: Is confirmed only when the AF sensor sees an in-focus subject. The only apparent differences between the two modes are that a focus-locking mode halts on focus confirmation, and a continuously focusing mode has predictive elements to work with moving targets, which suggests they are the same closed-loop process. Although AF sensors are typically one-dimensional photosensitive strips (only a few pixels high and

2236-400: Is derived from the original K-mount. It allows the lens's aperture to be set by the body, and thus permits shutter priority and program auto exposure modes. It was introduced in 1983, and is supported by A-series and P-series bodies; Pentax lenses that support it are marked 'SMC Pentax-A'. It is completely backward-compatible with the original K-mount. The aperture on the lens is set from

2322-449: Is great debate in the Pentax community over the applicability and safety of adapters other than those supplied by Pentax. Many users of third-party infinity-focus adapters, such as Bowers, report difficulty in removing the adapters from camera bodies. Such adapters may require modification before they may be safely used. Official Pentax adapters, and flanged non-infinity-focus adapters, do not provoke such problems. Many old M42 lenses have

2408-428: Is the phase-detection auto-focus system used in single-lens reflex cameras since the 1985s. The passive phase-detection auto-focus needs some contrast to work with, making it difficult to use in low-light scenarios or on even surfaces. An AF illuminator will illuminate the scene and project contrast patterns onto even surfaces, so that phase-detection auto-focus can work under these conditions as well. A newer form of

2494-505: Is the same as the K AF -mount except that it adds two extra power contacts to the inside of the mounting ring and transmits modulation transfer function (MTF) data through the digital seventh contact. The power contacts were originally used for power zooming. Since the introduction of the K10D digital SLR model, they are mainly used for powering Silent Drive Motor and DC motor lenses. The K10D / K100D Super and later cameras do not have

2580-464: Is transmitted digitally through the data pin and the aperture is stopped down through a motor built into the lens. It also introduced a new type of autofocus motor, designated PLM or Pulse Motor . At the time of its introduction, the following Pentax DSLR bodies were compatible with the new mount: K-70 , K-50 , K-S2 , K-S1 , K-1 , K-3 II , with all but the K-70 requiring a firmware update. Also after

2666-402: Is typically used to mutually compensate for the intrinsical weaknesses of the various methods in order to increase the overall reliability and accuracy or to speed up AF function. A rare example of an early hybrid system is the combination of an active IR or ultrasonic auto-focus system with a passive phase-detection system. An IR or ultrasonic system based on reflection will work regardless of

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2752-657: Is used to control an electromechanical system that adjusts the focus of the optical system. A variation of autofocus is an electronic rangefinder , in which focus data are provided to the operator, but adjustment of the optical system is still performed manually. The speed of the AF system is highly dependent on the widest aperture offered by the lens at the current focal length. F-stops of around f / 2 to f / 2.8 are generally considered best for focusing speed and accuracy. Faster lenses than this (e.g.: f / 1.4 or f / 1.8) typically have very low depth of field, meaning that it takes longer to achieve correct focus, despite

2838-540: The Pentax *ist DS2 is a minor upgrade to the original model that increased the size of the rear LCD from 2.0" to 2.5". VIDEO: 720p / 1080p / 4K This camera-related article is a stub . You can help Misplaced Pages by expanding it . 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 (SLR) cameras . It

2924-557: The Yashica 230 AF . Trap focus is also possible on some Pentax (e.g. K-x and K-5 ), Nikon , and Canon EOS cameras. The EOS 1D can do it using software on an attached computer, whereas cameras like the EOS 40D and 7D have a custom function (III-1 and III-4 respectively) which can stop the camera trying to focus after it fails. On EOS cameras without genuine trap focus, a hack called "almost trap focus" can be used, which achieves some of

3010-630: The depth of field (DOF) at the widest aperture of the lens is common in professional AF SLR cameras. Most multi-sensor AF cameras allow manual selection of the active sensor, and many offer automatic selection of the sensor using algorithms which attempt to discern the location of the subject. Some AF cameras are able to detect whether the subject is moving towards or away from the camera, including speed and acceleration, and keep focus — a function used mainly in sports and other action photography. Canon cameras call this AI servo ; Nikon cameras call it "continuous focus". The data collected from AF sensors

3096-644: The Adaptall-2 web site. Manual focus Auto focus A lot of Sears cameras were made by Ricoh or Chinon and use the Pentax K-mount. Some are simply rebadged models, while others are quite different. Angenieux a lens manufacturer in France , mainly known for its movie equipment than for photographic lenses, but it has built optics for Leica , Nikon , Canon and a few K-mount lenses. The Agfa K mount cameras were rebadged Chinons. Arsat

3182-463: The Cimko brand. (Some of the lenses below may not have ever been sold under the Cimko brand.) Cosmicar is a division of Pentax, it commercialized video lenses, but some were released for the K-mount. Autofocus An autofocus ( AF ) optical system uses a sensor , a control system and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has

3268-473: The FA and FA* series lenses from 1991. Their first K AF -mount Pentax lenses with AF had been introduced in 1989. In 1992, Nikon changed back to lens integrated motors with their AF-I and AF-S range of lenses; today their entry-level DSLRs do not have a focus motor in the body due to the availability of motors in all new developed AF-Lenses . Active AF systems measure distance to the subject independently of

3354-515: The K AF2 , but lacks the screw-drive autofocus drive shaft. Another way of looking at it is that it adds the power zoom/in-lens autofocus motor contacts to the K A2 mount. The K AF4 -mount was introduced in June 2016 with the HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE lens. It is identical with K AF3 , apart from the missing aperture control lever. Instead, aperture control information

3440-426: The K-mount, typically as a M39-M42 adapter ring that is mounted in a M42-PK adapter; they may focus to infinity. Pentax supplies adapters to fit M42 screw-mount lenses, as do several third-party manufacturers. The M42 screw-mount system was used by Pentax prior to the introduction of the K-mount. Pentax designed the K-mount wide enough to allow an adapter to fit between the M42 thread and the K bayonet. They also kept

3526-616: The ZK lenses would be discontinued that year. [1] Cima Kogaku had a patented system that allowed them to build common lens bodies, and add the appropriate lens mount at the factory. The Pentax version was only K-mount, not KA-mount. They mostly sold their lenses on an OEM basis, with them sold under a variety of different brands. In the UK, they were sold by Photax as Super-Paragon PMC lenses. Tokyo Kogaku sold them as AM Topcor lenses for their Topcon RM300 camera. Cima Kogaku also sold them directly under

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3612-421: The bayonet ring. One is slightly 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 slightly 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

3698-541: The body by the same stop-down lever found on the original K-mount, but on K A -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 easily set a specific aperture, since the relationship to F stops is linear. The lenses add an 'A' setting on the aperture dial, which gives the body control of the aperture. Other, numeric settings are used for manual aperture modes— aperture priority and full manual mode. Six electrical contacts are added to

3784-451: The bottom which tells the body when the aperture ring has been set to the "P" setting (similar to the "A" setting on Pentax K A lenses). The 'P' setting is not compatible with the 'A' setting as the 'P' pin is in a different location than the 'A' contact on Pentax 'A' lenses and the flange on Pentax bodies. The R-K-mount is used on Rikenon P lenses, Ricoh bodies that include the letter 'P' in their model number, and some non-Ricoh lenses. It

3870-404: The camera body and gears in the lens ("screw drive") or through electronic transmission of the drive instruction through contacts in the mount plate to a motor in the lens. Lens-based motors can be of a number of different types, but are often ultrasonic motors or stepper motors . Magnets are often used in electromagnetic motors, such as Voice coil motors (VCMs) and Stepper motor , which move

3956-556: The camera body coupled with a motorized lens , became the first autofocus 35 mm SLR in 1981. In 1983 Nikon released the F3AF , their first autofocus camera, which was based on a similar concept to the ME-F. The Minolta 7000 , released in 1985, was the first SLR with an integrated autofocus system, meaning both the AF sensors and the drive motor were housed in the camera body, as well as an integrated film advance winder — which

4042-428: The camera uses flash focus assist and is set to an operation mode that overrides the flash, it may also disable the focus assist. Thus, autofocus may fail to acquire the subject. Similar stroboscopic flashing is sometimes used to reduce the red-eye effect , but this is only intended to constrict the subject's eye pupils before the shot. Some external flash guns have integrated autofocus assist lamps that replace

4128-399: The camera's autofocus system uses to achieve focus. Many cameras and nearly all camera phones lack a dedicated autofocus assist lamp. Instead, they use their built-in flash, illuminating the subject with bursts of light. This aids the autofocus system in the same fashion as a dedicated assist light, but has the disadvantage of startling or annoying people. Another disadvantage is that if

4214-399: The camera. When in use, the lens will constantly maintain its focus on the subject, hence it is commonly used for sports and action photography . AI refers to artificial intelligence : algorithms that constantly predict where a subject is about to be based on its speed and acceleration data from the autofocus sensor. Modern autofocus is done through one of two mechanisms; either a motor in

4300-416: The camera. Two micro-lenses capture the light rays coming from the opposite sides of the lens and divert it to the AF sensor, creating a simple rangefinder with a base within the lens's diameter. The two images are then analysed for similar light intensity patterns (peaks and valleys) and the separation error is calculated in order to find whether the object is in front focus or back focus position. This gives

4386-488: The different flange distance. Pentax made adapters for its medium-format lenses to use on the K-mount, both the 645 and 6×7, and for the Hasselblad Bayonet type. Also there is a Pentacon-Six (Kiev88 CM) adapter still in production and a shift adapter to use Pentacon lenses as shift lens. Mounts used for Telescopes, microscopes and generic optics. The T-mount was initially developed by Tamron (1957) to allow

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4472-413: The direction and an estimate of the required amount of focus-ring movement. PD AF in a continuously focusing mode (e.g. "AI Servo" for Canon , "AF-C" for Nikon , Pentax and Sony ) is a closed-loop control process. PD AF in a focus-locking mode (e.g. "One-Shot" for Canon , "AF-S" for Nikon and Sony ) is widely believed to be a "one measurement, one movement" open-loop control process, but focus

4558-643: The easy adaption of generic 35 mm SLR optics into multiple mounts. The T-mount is a 42 mm diameter 0.75 mm pitch screw mount with a 55 mm flange focal distance . Later versions (T2, T4, TX) were more advanced and complex. Several other manufacturers besides Tamron have used these mounts. Because the T-mount is still used for many telescopes and microscopes, they are still available new. Note that while both T-mount and M42-mount are 42mm screw mount systems, and will mount if they are forced, they are not compatible. The difference in pitch can cause damage to

4644-498: The effective measurement basis is typically set to between 1:5.6 and 1:6.7, so that AF continues to work with slow lenses (at least for as long as they are not stopped down). This, however, reduces the intrinsical accuracy of the autofocus system, even if fast lenses are used. Since the effective measurement basis is an optical property of the actual implementation, it cannot be changed easily. Very few cameras provide multi-PD-AF systems with several switchable measurement bases depending on

4730-401: The effects of trap focus. By using the custom firmware Magic Lantern , some Canon DSLRs can perform trap focus. AI Servo is an autofocus mode found on Canon SLR cameras, and in other brands such as Nikon , Sony , and Pentax , under the name "continuous focus" (AF-C). Also referred to as focus tracking , it is used to track a subject as it moves around the frame, or toward and away from

4816-415: The focal range, stopping precisely at the point where maximal contrast is detected. This means that lenses designed for phase detection often perform poorly on camera bodies that use contrast detection. The assist light (also known as AF illuminator) "activates" passive autofocus systems in low-light and low- contrast situations in some cameras. The lamp projects visible or IR light onto the subject, which

4902-444: The focus of the lens. This makes the lenses less bulky than the earlier K F -mount, which had both a motor and batteries inside the lens. It also 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, and lens size. This information is used to make better exposure decisions, along with

4988-427: The front of the camera). The only linkage with the camera is mechanical and 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

5074-456: The increased amount of light. Most consumer camera systems will only autofocus reliably with lenses that have a widest aperture of at least f / 5.6, whilst professional models can often cope with a widest aperture of f / 8, which is particularly useful for lenses used in conjunction with teleconverters . Between 1960 and 1973, Leitz (Leica) patented an array of autofocus and corresponding sensor technologies. In 1976, Leica had presented

5160-565: The latter case, infrared light is usually used to triangulate the distance to the subject. Compact cameras including the Nikon 35TiQD and 28TiQD , the Canon AF35M , and the Contax T2 and T3 , as well as early video cameras, used this system. A newer approach included in some consumer electronic devices, like mobile phones, is based on the time-of-flight principle, which involves shining

5246-494: The lens directly. Passive AF systems determine correct focus by performing passive analysis of the image that is entering the optical system. They generally do not direct any energy, such as ultrasonic sound or infrared light waves, toward the subject. (However, an autofocus assist beam of usually infrared light is required when there is not enough light to take passive measurements.) Passive autofocusing can be achieved by phase detection or contrast measurement. Phase detection (PD)

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5332-407: The lens elements to achieve precise focusing. The magnetic field interacts with coils to produce motion for adjusting the lens position quickly and accurately based on focus requirements. Magnets are ideal for this purpose because they enable smooth and rapid adjustments without direct physical contact, enhancing durability and response time. Some camera bodies, including all Canon EOS bodies and

5418-593: The lens right into (or close to) focus without additional measurements. Additional measurements on the fly, however, can improve accuracy or help keep track of moving objects. However, the accuracy of phase-detection auto-focus depends on its effective measurement basis. If the measurement basis is large, measurements are very accurate, but can only work with lenses with a large geometrical aperture (e.g. 1:2.8 or larger). Even with high contrasty objects, phase-detection AF cannot work at all with lenses slower than its effective measurement basis. In order to work with most lenses,

5504-451: The lens stopped down. Also, since contrast AF continues to work in stopped-down mode rather than only in open-aperture mode, it is immune to aperture-based focus shift errors phase-detection AF systems suffer since they cannot work in stopped-down mode. Thereby, contrast AF makes arbitrary fine-focus adjustments by the user unnecessary. Also, contrast AF is immune to focusing errors due to surfaces with repeating patterns and they can work over

5590-401: The lens used in order to allow normal auto-focusing with most lenses, and more accurate focusing with fast lenses. Contrast AF does not have this inherent design limitation on accuracy as it only needs a minimal object contrast to work with. Once this is available, it can work with high accuracy regardless of the speed of a lens; in fact, for as long as this condition is met, it can even work with

5676-522: The lens, adapter or camera mount if they are confused. These are adaptors designed by Tamron to allow the transfer of aperture setting from lens to camera or vice verse, including the Adapt-A-matic (1969), Adaptall (1973) and Adaptall-2 (1979). When Pentax introduced the KA-mount in 1983 Tamron upgraded their Adaptall-2 K-mount into an Adaptall-2 KA-mount. For more details see the Tamron article or

5762-419: The lens. When setting up a shot this keeps the diaphragm fully 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, and 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

5848-406: The light conditions, but can be easily fooled by obstacles like window glasses, and the accuracy is typically restricted to a rather limited number of steps. Phase-detection autofocus "sees" through window glasses without problems and is much more accurate, but it does not work in low-light conditions or on surfaces without contrasts or with repeating patterns. A very common example of combined usage

5934-516: The more sophisticated stand-alone sensors, but since the fine focusing is now carried out through contrast focusing, the phase-detection AF sensors are only need to provide coarse directional information in order to speed up the contrast auto-focusing process. In July, 2010, Fujifilm announced a compact camera, the F300EXR, which included a hybrid autofocus system consisting of both phase-detection and contrast-based elements. The sensors implementing

6020-508: The multi-segmented metering that was introduced in cameras using the K AF -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 a dial on the camera body, and no longer on the lens. Pre-A lenses can only be used in manual stop down metering mode and manual flash mode. The K AF2 -mount

6106-412: The norm on most mirrorless cameras giving them significantly better AF tracking performance compared to contrast detection. Contrast detection places different constraints on lens design when compared with phase detection. While phase detection requires the lens to move its focus point quickly and directly to a new position, contrast-detection autofocus instead employs lenses that can quickly sweep through

6192-492: The optical system, and subsequently adjust the optical system for correct focus. There are various ways to measure distance, including ultrasonic sound waves and infrared light. In the first case, sound waves are emitted from the camera, and by measuring the delay in their reflection, distance to the subject is calculated. Polaroid cameras including the Spectra and SX-70 were known for successfully applying this system. In

6278-532: The original K-mount include the K series, the M series except the ME F, and 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" K AF -mount bodies (see below). The K F -mount

6364-447: The phase-detection AF can assist a contrast AF system to be fast and accurate at the same time, to compensate aperture-based focus-shift errors, and to continue to work with lenses stopped down, as, for example, in stopped-down measuring or video mode. Recent developments towards mirrorless cameras seek to integrate the phase-detection AF sensors into the image sensor itself. Typically, these phase-detection sensors are not as accurate as

6450-406: The phase-detection AF in this camera are integrated into the camera's Super CCD EXR. Currently it is used by Fujifilm FinePix Series, Fujifilm X100S , Ricoh , Nikon 1 series , Canon EOS 650D/Rebel T4i and Samsung NX300 . Active systems will typically not focus through windows, since sound waves and infrared light are reflected by the glass. With passive systems this will generally not be

6536-595: The photographer to use cheaper TTL flashes rather than the current offerings from Pentax and Samsung with 'pre-flash' operation, which can cause some subjects to blink. Unlike red-eye reduction pre-flash, the P-TTL pre-flash for metering purposes fires only a brief moment before the main flash. Looking through the viewfinder, it can be seen before the mirror flips up. Firmware version 2.02 adds SDHC cards support, continuous AF support, and auto ISO mode (selectable from 200–400, 200–800, 200–1600, 200–3200 ISO). Introduced in 2005,

6622-429: The same flange focal distance (also called registration distance or register) as the M42 screw-mount, so that M42 lenses focus correctly using the correct adapter (such as Pentax original or Bower). There are however other third-party adapters that add to the flange focal distance so that one loses the ability to focus to infinity. The loss of infinity-focus may not be significant in macro or close-up photography. There

6708-400: The shutter when an object is in focus. The technique works by choosing the focus adjustment (turning AF off), then setting the shooting mode to "Single" (AF-S), or more specifically focus priority, then depressing the shutter – when the subject moves into focus, the AF detects this (though it does not change the focus), and a shot is taken. The first SLR to implement trap focusing was

6794-531: The stroboscopic on-camera flash. Many of them are red and less obtrusive. Another way to assist contrast based AF systems in low light is to beam a laser pattern on to the subject. The laser method is commercially called Hologram AF Laser and was used in Sony CyberShot cameras around the year 2003, including Sony's F707, F717 and F828 models. In a hybrid autofocus system, focus is achieved by combining two or more methods, such as: The double effort

6880-454: The whole frame, not just near the center of the frame, as phase-detection AF does. The down-side, however, is that contrast AF is a closed-loop iterative process of shifting the focus back and forth in rapid succession. Compared to phase-detection AF, contrast AF is slow, since the speed of the focus iteration process is mechanically limited and this measurement method does not provide any directional information. Combining both measurement methods,

6966-422: The “green button” on the camera before taking a shot. This variation of the mount is commonly referred to as the “crippled“ K-mount. The R-K-mount is a variation on the original K-mount by Ricoh . It supports Ricoh's own implementation of shutter priority and auto exposure modes, similar to the K A -mount but much simpler. The only addition to the original K-mount is a small pin, commonly dubbed Ricoh pin , at

7052-452: Was Pentax's first attempt at an autofocus system. This autofocus system used sensors in the camera body and 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 (towards and away from infinity) and two appear to have been unused and may have been reserved for future functionality. The K F -mount

7138-561: Was created by Pentax in 1975, and has since been used by all Pentax 35 mm and digital SLRs and also the MILC Pentax K-01 . A number of other manufacturers have also 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 the original K-mount, or to all its variations. Originally designed by Zeiss for an alliance with Pentax, it

7224-457: 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 (when looking at

7310-697: Was largely a failure. Only one camera and one lens ever 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 (with gears) and batteries to power it. K F 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 which feature an aperture ring. 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" K AF bodies. The K A -mount

7396-408: Was to become the standard configuration for SLR cameras from this manufacturer, and also Nikon abandoned their F3AF system and integrated the autofocus-motor and sensors in the body. Canon decided to discontinue their FD mount and switched to the completely electronic EF mount with motorised lenses in 1987. Pentax was the first to introduce focusing distance measurement for SLR cameras with

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