Pentax K mount

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The Pentax K mount is a lens mount standard for mounting interchangeable photographic lenses to 35 mm single-lens reflex (SLR) cameras. It was created by Pentax in 1976, and has been used by all 35 mm and digital Pentax SLRs since. A number of other manufacturers have also produced many K mount lenses and K mount cameras.

Contents 1 Mounts 1.1 K mount 1.2 KF mount 1.3 KA mount 1.4 KAF mount 1.5 KAF2 mount 1.6 KA2 mount 1.7 "Crippled" KAF mount 2 Cameras 2.1 Pentax 2.2 Chinon 2.3 Cosina 2.4 Miranda 2.5 Ricoh 2.6 Sears 2.7 Vivitar 2.8 Zenit 3 Lenses 3.1 Pentax primes 3.2 Pentax zooms 3.3 Sigma 3.4 Tamron 3.5 Tokina 3.6 Vivitar 3.7 Voigtlander 3.8 Vologda 3.9 Zenit 4 More information

[edit] Mounts

The K mount has undergone a number of evolutions over the years as new functionality has been added.

[edit] K mount

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 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 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 of course 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, and the LX. Lenses that support it include those labelled 'SMC Pentax' and 'SMC Pentax-M'. The bodies cannot use FAJ lenses since these lack an aperture ring. The lenses can be used on all Pentax bodies but can only be used in stopped down mode with "crippled" K_AF mount bodies.

[edit] K_F mount

The K_F mount 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 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[1] since it had to enclose both the focusing motor (with gears) and batteries to power it. Compare the Canon EF lens mount which powers the lens from the camera body, and the later use of ultrasonic motors (USM) by Canon in its lenses.

The ME F can use all Pentax K-mount lenses except for FAJ lenses, which lack 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.

[edit] K_A mount

The K_A mount is derived from the original K mount. It allows the lens' aperture to be set by the body, and thus permits shutter priority and program autoexposure 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 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 the bayonet ring. One is slightly recessed and allows the lens to communicate whether the aperture setting is set at 'A'. 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 out of contact. The other five contacts are used to encode the lens' aperture range. The matching contacts on the lens are either conducting or non-conducting, making the setting binary 1 or 0, respectively. Two contacts encode the lens' minimum aperture—f/16, f/22, f/32 or f/45. Although no Pentax K-mount lenses have ever had an f/16 minimum aperture, OEM lenses often have. The other three encode the lens' maximum aperture; their meaning is different for each encoding of minimum aperture.

[edit] K_AF mount

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 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 the multi-segmented metering that was introduced in cameras using the K_AF mount.

[edit] K_AF2 mount

The K_AF2 mount adds to the K_AF mount two extra contacts to the inside of the mounting ring for power zooming (on the K10D digital SLR model, these power contacts can also power Supersonic Direct Drive lenses - similar to Canon USM), and transmits modular transfer function (MTF) data through the digital seventh contact.

[edit] K_A2 mount

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.

[edit] "Crippled" K_AF mount

The "crippled" K_AF mount is used on the MZ-30/ZX-30, MZ-50/ZX-50, MZ-60/ZX-60, the *ist series and recent K series cameras. The only difference between the regular K_AF mount and the crippled version is the removal of the stop-down coupler/indicator. The result is that most of these bodies can only use lenses which have an "A" setting on the aperture ring, or "crippled" K_AF lenses, which are essentially always in this mode. The *ist and K range of cameras have a setting which allows these lenses to be used only in manual exposure mode. The use of the "crippled" K_AF mount excludes many fully manual lenses, both old and new. According to Pentax, K series dslr cameras are compatible with any PENTAX lens ever produced. An adaptor is required for screw mount and 645/67 lenses. http://www.pentaxslr.com/bodies/k100

[edit] Cameras

[edit] Pentax

Manual focus

• K - K2, KX, KM, K1000
• K - ME, MG, MV, MX
• K - LX
• K_A - SuperA, ProgramA, A3
• K_A - P3, P5, P30t

Auto focus

• K_F - ME F
• K_AF - SFX, SF7, MZ-6, MZ-7
• K_AF2 - Z-1, Z-5, Z-10, Z-20, Z-50, Z-70
• K_AF2 - MZ-S, MZ-3, MZ-6, MZ-10
• K_A2 - MZ-M
• "crippled" K_AF - MZ-30, MZ-50, MZ-60, *istD, *istDS(2), *istDL(2), K100D, K10D

[edit] Chinon

• CE-4, CE-4s, CA-4, CM-4
• CE-5, CG-5, CM-5, CP-5
• CP-6, CP-X
• CP-7, CM-7
• CP-9

[edit] Cosina

• CS-2, CS-3
• CT-10, CT-1A, CT-20, CT-7, CT-1G, CT-9

[edit] Miranda

• MS-3

[edit] Ricoh

• KR-5 series, KR-10, KR-30
• XR-1, XR-2, XR-500, XR-6, XR-7, XR-10, XR-20, XR-Solar, XR-M, XR-F, XR-P, XR-S, XR-X, XR-X 3PF

[edit] Sears

A lot of Sears cameras were made by Ricoh and use the Pentax K mount. Some are simply rebadged Ricoh models, while others are modified.

• KS-1000 - Ricoh XR-1
• KS-500 - Ricoh XR-500
• KS Auto - Ricoh XR-2S
• KS-1
• KS-2 - Based on Ricoh XR-10, but with aperture priority exposure
• KSX - A Ricoh KR-10
• KS Super
• KS Super II - fully automatic using a K_A mount

[edit] Vivitar

• V3800N

[edit] Zenit

• Automat, 20, 21, 22, 14, photosniper FS-5
• AM, AM2, AP, 2000, APK, KM, 122K, 212K

[edit] Lenses

The following list gives only a selection from several hundred lenses made for the K mount.

[edit] Sigma

• 8mm f/3.5 EX Fisheye
• 12-24mm f/4.5-5.6
• 14mm f/2.8 EX
• 15mm f/2.8 EX DG Fisheye
• 15-30mm f/3.5-4.5
• 17-70mm f/2.8-4.5 DC
• 18-50mm f/2.8 EX DC
• 20mm f/1.8 EX DG
• 20-40mm f/2.8
• 24mm f/1.8 EX DG
• 28mm f/1.8 EX DG
• 24-60mm f/2.8 EX DG
• 24-70mm f/2.8 EX DG
• 28-70mm f/2.8 EX DG
• 70-200mm f/2.8 EX DG APO
• 135-400mm f/4.5-5.6 DG APO
• 170-500mm f/5-6.3 DG APO
• 500mm f/4.5 EX DG APO
• 800mm f/5.6 EX DG APO

[edit] Tamron

• AF 14mm f/2.8
• AF 28-75mm f/2.8 XR Di
• AF 90mm f/2.8 Macro Di

[edit] Tokina

• EL 28mm f/2.8
• 20-35mm f/2.8 AT-X Pro
• 24-200mm f/3.5-5.6 AT-X

[edit] Vivitar

• MC 50mm f/1.7

[edit] Voigtlander

• 40mm SL Ultron f/2.0
• 90mm SL f/3.5 APO-Lanthar
• 125mm SL f/2.5 APO-Lanthar Macro

[edit] Vologda

• MC Mir-47K 20mm

[edit] Zenit

• MC Helios-44K-4
• MC Zenitar-K2 50 mm f/2
• MC Zenitar-K 16 mm f/2.8 fisheye
• MC APO Telezenitar-K 300 mm f/4.5
• MC Variozenitar-K 25-45 mm f/2.8-3.5

[edit] More information

• Bojidar Dimitrov's Pentax K-Mount Page
• List of cameras with a Pentax K mount