K bayonet
The K-bayonet is a lens bayonet from the camera brand Pentax for SLR cameras . It was introduced in 1975 as the successor to the M42 screw thread that Pentax had been using since 1957 in the Asahi Pentax and all successor models including the Spotmatic . The back focus of 45.46 mm was retained. Pentax introduced the original K bayonet with the launch of the first three K cameras: KM , KX and K2 . The lens connection has been further developed several times and is also used in a modified form in the digital SLR cameras from Pentax and Samsung.
compatibility
The K-bayonet was proposed by Pentax as an open standard for SLR cameras, which is why it is also found in a number of other brands and manufacturers, e.g. B. Zenit , Revueflex (brand of Quelle GmbH ) or Ricoh (which took over the photo division of the Pentax brand from the Hoya group in October 2011 ). From 2005 to 2008, Samsung finally also offered its camera models GX-1S , GX-1L , GX-10 and GX-20 digital SLR cameras with K-bayonet, which are slightly modified versions of the Pentax models * DS2 , * is DL2 , K10D and K20D acted. As a result, however, Samsung decided to also develop its own bayonet system, the NX bayonet , which was launched on the market in 2010 and is no longer compatible with the K bayonet .
Pentax has ensured extensive compatibility between lenses and cameras of the various generations. As a result, K bayonet lenses that are more than 30 years old can be used with a modern AF housing or a DSLR - with restrictions - and, conversely, many modern lenses can also be used on an old Pentax K2 from 1975. Due to the identical flange focal length , many M42 and T-2 lenses can be used with an adapter ring on a camera with a K bayonet. Pentax also offers lens adapters for connecting lenses of the medium format systems 645 and 67 to cameras with a K bayonet. In order to be able to use all focus functions with manual lenses (e.g. focus display, focus trap ), the lens contacts on the camera must be bridged. In the simplest case, this can be done by the contact surface of the lens, which for this purpose must be electrically conductive, i.e. metallic and free of color.
The different versions of the K bayonet (such as K, K A , K AF , see below) are only mechanically fully compatible with each other, they differ in a number of details that have changed over time. Many newer lenses of the SMC-DA and SMC-DA * series do not illuminate the full image circle of a 35mm camera, as they are only intended for DSLRs with a smaller image sensor from the outset. In addition, lenses of the SMC-FA-J , SMC-DA and SMC-DA * series , which do not have an aperture ring, do not allow the manual aperture control required for older cameras. Conversely, with old lenses (up to around 1982), whose aperture rings did not yet offer an A position (for automatic ), the exposure programs of newer cameras can only be used to a limited extent.
The company's policy of compatibility is also expressed in the fact that when lenses with ultrasonic motors are introduced (since 2007), both cameras and most lenses have a double focus drive, which allows new lenses to be used with older cameras and new cameras work together with old lenses.
Variants of the K bayonet
Overview
- Since 1975: "K" - in SMC / SMC-M lenses.
Original version with mechanical diaphragm coupling (diaphragm simulation and spring diaphragm ). - 1981: "K F " - in the SMC AF lens
First autofocus variant for the Pentax ME-F, the first AF reflex camera, otherwise not used. - Since 1983: "K A " - in SMC-A lenses
"A" position on the aperture ring with locking option. Six electrical contacts on the bayonet of the camera housing scan electrically conductive or insulating surfaces on the lens as well as the "A" position pin. With a 5-bit code, the contacts transmit the smallest aperture (16, 22, 32 or 45) and the number of steps by which the aperture can be opened (gives the aperture range) and allow aperture and program automatic as well as matrix exposure metering. The 6th contact signals the "A" position. Series of cameras: A and P.
- Since 1987: “K AF ” - in SMC-F lenses
Similar to the K A bayonet, but with an additional mechanical coupling for the camera's internal auto focus motor and an additional electrical contact for serial information transfer from the lens to the camera body. Introduced for the SF series, can also be found in the first MZ models. - Since 1991: "K AF2 " - for SMC-FA lenses
The second generation of the autofocus-capable K bayonet enables the transmission of MTF values from the lens and has two electrical contacts for the power zoom function of certain lenses; for the PZ models as well as the later MZ models (MZ-S, MZ-3, MZ-5 etc.) - Since 1997: "K A2 "
As K AF , but without autofocus function especially for the MZ-M / ZX-M models - Since 1997: "K AF " version without mechanical aperture simulator
Used in models MZ-30 / ZX-30, MZ-50 / ZX-50, MZ-60 / ZX-60, which * is / * is D-series and the K100D / K110D. - Since 2006: "K AF2 " version without mechanical diaphragm simulator
The contacts originally built in to control power zoom lenses are now used to control the SDM autofocus drive (SDM: Supersonic Drive Motor or Super Dynamic Motor, ultrasonic motor ) of new lenses. Used in all DSLRs since the K10D and K100D Super. The K10D can either control the SDM autofocus or power zoom. - Since 2008: "K AF3 " (previously only on the
lens side ) lenses with integrated SDM drive, but without mechanical AF coupling to the camera housing. These lenses can be focused manually with camera models that came onto the market before autumn 2006, otherwise work like K AF2 . Cameras do not have the designation K AF3 , because so far (as of February 2016) Pentax has not released a housing that, like the K AF3 lenses, does not have the AF motor in the housing. - from 2016: "K AF4 " (previously only on the
lens side ) Lenses with electromagnetic aperture control, without mechanical aperture lever. These lenses can no longer be used sensibly on older camera housings for which no software update is planned.
functionality
The original Pentax K bayonet has two mechanical interfaces between the camera and lens: the driver for the aperture simulator, which transfers the aperture set on the lens to the camera, and the aperture lever, which is used to switch between the working aperture and the open aperture. When the lens is removed, the diaphragm closes directly to the value set on the diaphragm ring by spring force, but can be opened using the diaphragm lever. If the lens is attached to a camera housing, a lever in the camera housing activates the aperture lever so that the aperture is opened completely. Only during the exposure - coupled to the mechanism of the mirror - does the camera release the aperture lever and the aperture closes to the set value by spring force. The driver for the aperture simulator turns a ring-shaped potentiometer, the resistance value of which specifies the set aperture for the exposure meter.
In addition to the six electrical contacts described above, the PK A bayonet has another, non-obvious change: the adjustment path of the diaphragm lever is proportional to the area of the diaphragm, i.e. the light value, instead of proportional to the diameter of the diaphragm opening. Otherwise, the function is identical to the PK bayonet and is therefore fully compatible with older cameras.
This means that a camera housing with automatic iris can freely control the iris via the adjustment path of the iris lever, provided the iris ring is in the A position (smallest iris and A contact closed).
Development since 1997
In 1997, the MZ-50 / ZX-50 also introduced a simplified version of the previous autofocus bayonet. This lacks the electrical contacts for the power zoom function and the mechanical scanning of the aperture value preselected on the lens. The aperture can therefore no longer be set on the lens itself in automatic mode, but only via a rotary knob on the camera. This means that automatic exposure systems can no longer be used with lenses that have an aperture ring without an A-position.
These restrictions also apply to the film-based camera * ist built from 2003 and the DSLRs of the * ist-D series as well as K100D / K110D . For the exposure measurement with the traditional use of the aperture ring, a workaround was introduced in the Pentax DSLRs: In M mode (manual setting), the aperture is automatically briefly dimmed at the push of a button, the exposure is measured and the exposure time that matches the preselected aperture value is set (auto working aperture measurement ) . The use of the aperture ring must first be enabled in the camera menu.
In 2003, the SMC-FA-J series saw the first lenses without an aperture ring to match the cameras without mechanical aperture value scanning. The SMC-D-FA series lenses, which were built from 2004 , again have an aperture ring, are optimized for use on DSLRs (as the letter "D" in the name indicates) and, like all previous lenses, illuminate the image circle of 35mm cameras. The SMC-DA lens series , also sold from 2004, is also "digitally optimized", has no aperture ring and has been corrected for the smaller image circle of DSLRs with image sensors in APS-C format .
In 2006, the first Pentax camera came onto the market with the K10D , which is able to control lenses with ultrasound focusing (called SDM at Pentax ). For this purpose, the power zoom contacts of the K AF2 bayonet have been integrated into the bayonet, which in this model support either power zoom or SDM lenses. As additional cameras, the K100D Super , K20D , K200D and all later models received the ability to SDM focusing with appropriate lenses. All cameras also keep the autofocus motor in the housing and can therefore automatically focus on older AF lenses that do not have their own motor.
The first lenses with SDM drive belong to the SMC-DA * series and have a dual focus drive, so they can be focused on older, non-SDM-compatible cameras using the AF motor on the housing. Like the DA series, they do not have an aperture ring. In the summer of 2008 Pentax launched the smc PENTAX-DA 17-70mm F4 AL [IF] SDM , the first lens that can only be automatically focused using an SDM drive. On older cameras like the K100D (without Super ) and * ist DL this lens can be focused manually.
With the announcement of the new K-70 in June 2016, Pentax presented the first lens with electromagnetic iris control. The version of the bayonet called by Pentax K AF4 does not require any mechanical coupling to the camera housing. In addition to the new K-70, according to Pentax, K-1, K-3 / K-3II, K-S2 and K-S1 can be used after a software update. The K-70 still has the K AF4 bayonet and thus additional mechanical aperture control and an AF motor.
Ricoh RK bayonet
The RK bayonet is a variant of the Pentax K bayonet, which was used by the Ricoh company and, similar to the KA bayonet, enables aperture control by the camera. It differs from the Pentax version in that it has a spring-loaded pin in the lens bayonet, which on newer Pentax cameras can get caught in the recess for the AF spindle in the camera bayonet, thus preventing the lens from being removed. The pin , also known as the Ricoh pin , should be removed before the lens is mounted on a modern Pentax camera. This does not apply to all Ricoh lenses, but only to those with an aperture ring setting corresponding to the A position, which were intended for camera-side aperture control.
Sigma SA bayonet
Hybrid between K and Canon EOS bayonets. EOS contacts and flange back of 44.0 mm instead of 45.46 mm. Mechanically identical to the K bayonet, but rotated 90 ° clockwise. K lenses fit Sigma SD cameras if the parts protruding into the camera, such as spring shutter levers, are removed. Due to the 1.5 mm lower flange focal length of SA compared to K, K lenses focus beyond infinity, but in most cases do not touch the sensitive UV-IR dust filter of the Sigma SD cameras. If this is the case, a spacer ring made of z. B. decuppered 1.5 mm FR circuit board material can be used between the lens and bayonet. With fixed focal lengths, there is often the simple option of resetting the stop of the focusing ring. This second option only applies to zoom lenses if the synchronization between focusing and focal length adjustment can be dispensed with, i.e. H. refocusing is accepted when zooming.
Compatibility table
The following table shows the compatibility of the Pentax K lenses with the corresponding cameras. The cameras are only differentiated here in terms of bayonet and analog or digital, although it should be noted that not all cameras listed always actually support all exposure modes possible with the bayonet (e.g. M, Av). The Pentax ME-F is not considered as a special case.
| Bayonet> | K, M | A. | F, FA, D-FA | FA Powerzoom | FA-J | DA, DA-L | DA-SDM, DA-DCM (KAF3) | DA, D-FA (KAF4) |
|---|---|---|---|---|---|---|---|---|
| Major change: camera |
Original version of the K bayonet | A position, electrical contacts | Drive for rod motor, additional contact for serial communication | Two contacts for power zoom | Elimination of the aperture ring | Small image circle | Autofocus drive in the lens | electromagnetic shutter control |
| K (K series, M series , LX ) | M, Av | M, Av | M, Av | M, Av | X | X | X | X |
| KA (A series, P series) | M, Av | M, Av, Tv, P | M, Av, Tv, P | M, Av, Tv, P | Tv, P | (Tv, P) 1 | (Tv, P) 1 | X |
| KAF | M, Av | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF | Tv, P, AF | (Tv, P) 1 | (Tv, P) 1 | X |
| KAF2 (MZ-S, MZ-3, MZ-5 etc.) | M, Av | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF, PZ | Tv, P, AF | (Tv, P) 1 | (Tv, P) 1 | X |
| KA2 (MZ-M / ZX-M) | M, Av | M, Av, Tv, P | M, Av, Tv, P | M, Av, Tv, P | Tv, P | (Tv, P) 1 | (Tv, P) 1 | X |
| KAF without aperture simulator (MZ-30 / ZX-30, * ist) | M. | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | (M, Av, Tv, P, AF) 1 | (M, Av, Tv, P) 1 | X |
| KAF digital without aperture simulator (* istD, * istDS, * istDL, K100D, K110D) | M +, Av0 | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P | X |
| KAF2 digital power zoom without aperture simulator ( K10D ) | M +, Av0 | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF, PZ 2 | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, SDM / DCM 2 | X |
| KAF2 digital SDM without aperture simulator (K100D Super, K20D , K200D , Km, K-7, K-5, K-5II, Kx, K-01) | M +, Av0 | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, SDM / DCM | X |
| KAF2 digital SDM without aperture simulator with ED interface: K-70. After firmware update: K-50, K-1, K-3, K-3II, K-S2, K-S1. |
M +, Av0 | M, Av, Tv, P | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, AF | M, Av, Tv, P, SDM / DCM | M, Av, Tv, P, SDM / DCM / PLM |
Legend:
- 1 - Image circle insufficient or edges with imaging defects
- 2 - The K10D can be switched from Powerzoom operation to SDM operation with a software update.
- AF - autofocus with rod motor
- Av - aperture priority
- Av0 - aperture priority only with an open aperture
- M - manual exposure with tracking metering
- M + - manual exposure with auto working aperture measurement, no tracking measurement
- P - automatic programs
- PLM - autofocus with pulse motor
- PZ - Powerzoom (K10D only with severely restricted functionality)
- SDM / DCM - autofocus with ultrasonic or DC motor (K10D from firmware 1.3)
- Tv - shutter priority
- X - not useful, as the smallest aperture is always set
Hints:
- On cameras with the K AF / K AF2 bayonet without an aperture simulator, the aperture is set on the camera side using a rotary knob with automatic aperture control and manual exposure.
Timeline of the K AF bayonet lenses from Pentax
Individual evidence
- ↑ http://kmp.pentaxians.eu/technology/k-mount/ka/
- ↑ http://www.ricoh-imaging.de/de/k-bajonett/HD-PENTAX-DA-55-300mmF4-5-6-3ED-PLM-WR-RE.html
Web links
- Glossary of Abbreviations for Pentax Lenses , Ricoh Imaging
- Abbreviations used for Pentax lenses , Ricoh Imaging
- Pentax technology glossary and lens abbreviation , Ricoh Imaging
- Detailed description of Arnold Stark's Pentax lens series
- Pentax K-Mount Page (English), comprehensive information on Pentax cameras, lenses and accessories for the K-bayonet