The Pentax K-Mount: History & Compatibility

The Pentax K-mount was released in 1975. Prior to that, Pentax used the M42 screw mount.

The K-mount was designed for manual focus 35mm film SLRS.

Over time, revisions have been made to lens designs. Big ones were autofocus and electronic connections.

Pentax is still releasing DSLRs that use the K-mount.

K-mount Versions

1. Original K-mount

• Bayonet mount.
• Mechanical aperture linkage for open-aperture metering.
• Supported by K series, M series (except ME F), and LX cameras.

2. KF-mount

• First autofocus attempt.
• Only used on the Pentax ME F with the SMC Pentax-AF 35-70 f2.8 lens.

3. KA-mount

• Adds aperture priority mode.
• Introduced in 1983. Supported by A-series and P-series cameras.

4. KAF-mount

• Autofocus uses a motor built into a camera.
• Similar to Nikon AF and D-series lenses.
• Introduced a small drive shaft to the KA-mount. (Similar to Nikon F-mount lenses of the time.)

5. KAF2, KA2, KAF3, and KAF4-mounts

• Added electrical contacts for digital communication with a camera body. Removes the physical linkage used to set maximum aperture information.
• Bodies lose open-aperture metering and will need to use stop-down metering on pre-A lenses. This is done by pressing the green button.

6. R-K-mount

• A variation by Ricoh for Rikenon P lenses. It supports Ricoh’s implementation of shutter priority and auto exposure metering modes.

K-mount Lens Compatibility

Table of K-Mount Lens Variations:

K-Series Lenses (Pre-A)

• The first generation of Pentax K-mount lenses.
• Not officially referred to as K series lenses but are often designated as such to distinguish them from later K-mount lenses.
• Exclusively manual focus lenses with no electronic features.
• Name starts with either upper case “SMC” or lower case “smc”, representing the Super-Multi-Coated lens coating.

M-Series Lenses (Pre-A)

• Followed the K series lenses.
• Manual K-mount lenses without electronic features.
• Generally smaller in size to match compact camera bodies like the Pentax MX and Pentax ME Super.

SMC Pentax-A Lenses

• Introduced “automatic” aperture settings.
• Had an aperture ring but also an “A” mode, allowing the camera to control the aperture automatically.

SMC Pentax-F Lenses

• First autofocus lenses for Pentax.
• Screw-drive type autofocus.
• Featured an aperture ring for manual control.

SMC Pentax-FA Lenses

• Designed for full-frame film SLR cameras.
• Screw-drive type autofocus.
• Introduces power zoom lenses.

SMC Pentax-FA-J Lenses

• No aperture ring.

SMC Pentax-D FA Lenses

• Coated for digital cameras but also support older 35mm camera formats.
• Some are weather resistant.
• Some lenses have aperture rings and others don’t.

SMC Pentax-DA Lenses

• Designed for Pentax digital cameras with an APS-C digital sensor.
• No aperture ring.

SMC Pentax-DA-L Lenses

• Lighter and cheaper versions of DA series zoom lenses.
• No aperture ring.

DA* Lenses

• Higher quality optics and better weather sealing.
• No aperture ring.

DA Limited Lenses

• High-quality prime lenses with metal housing.
• Compact in design.
• No aperture ring.

K-Mount Specifications

The Pentax K-mount is a bayonet style lens mount with 3 tabs for mounting. Originally designed to be used on 35mm SLRs. It is similar in appearance to the Nikon F-mount and Minolta MD-mount.

Later versions of the lens mount had electrical contacts and a drive shaft for autofocus added. The drive shaft would connect to an autofocus motor inside a camera body.

Lens Mount Adapter Compatility

The flange focal distance is 45.46 mm. This is the same distance as the M42 mount. This was done so that Pentax M42 lenses, used on cameras like the Spotmatic, could be used on K-mount cameras with a lens adapter.

However, due to the relatively large flange distance for a 35mm SLR camera, Pentax K-mount lenses cannot be easily adapted to other SLR or DSLR cameras. There are K-mount lens adapters for all mirrorless camera mounts.

Mirrorless cameras are ideal as autofocus and electronic features will not work. The adapted lens will have to be used in manual mode or aperture priority. If the lens doesn’t have a physical aperture ring, you will not be able to change the aperture.

There are some adapters that have glass optics to allow for focus to infinity. The optics are to compensate for the lens being further away from the imaging plane than it was designed for. Unfortunately, the optics are of poor quality, which greatly reduces image quality.

List of K-mount Film Cameras

K Series

• K2 (1975–1980): The flagship K-series camera featuring aperture-priority autoexposure and an electronic vertical metal focal-plane shutter.
• K2 DMD (1976–1980): Adds motor drive compatibility, data back support, and an exposure lock feature.
• KX (1975–1977): A manual SLR featuring fast SPD metering (Silicon Photodiode), mirror lockup, and full exposure information visible inside the viewfinder.
• KM (1975–1977): Adapted the Spotmatic F design to the K-mount, featuring depth-of-field preview and a self-timer.
• K1000 (1976–1997): Entry-level fully mechanical SLR designed for simplicity, low cost, and durability.

M Series

The MX is the only camera with a mechanical shutter. All of the other cameras use an electronically controlled, vertical-travel metal shutter.

• ME (1976–1980): Ultra-compact body with aperture-priority autoexposure and LED viewfinder readouts.
• MX (1976–1985): Full mechanical manual exposure, GPD light metering (Gallium Arsenide Phosphide Photo Diode), interchangeable focusing screens, and motor drive support.
• ME Super (1979–1984): Added manual exposure control via push-buttons and an increased top shutter speed of 1/2000s.
• MV (1979–1982): A simplified entry-level design featuring basic red-yellow-green exposure LEDs in the viewfinder.
• MV1 (1979–1982): Added a mechanical self-timer and external motor winder compatibility to the MV design.
• ME F (1981–1988): Pentax’s first TTL electronic autofocus system with dedicated lens mount contacts.
• MG (1982–1985): Added a complete LED shutter speed display in the viewfinder as an upgrade over the MV1.

LX

The LX (1980–2001) was Pentax’s flagship professional manual focus SLR featuring weather-sealed construction, interchangeable viewfinders, and off-the-film (OTF) TTL metering.

A Series

Pentax’s A series was designed to make 35mm photography easier for everyday people. These cameras added automatic modes and electronic aids. They gave shooters a simple, affordable way to enjoy film photography.

• Super A / Super PROGRAM (1983–1987): LCD screens and automatic modes that help take in focus and properly exposed photos.
• Program A / Program PLUS (1984–1988): Simpler version of the Super A with automated settings.
• A3/A3000 (1985–1987): Automatically winds the film after every photo.

P Series

The Pentax P are simple cameras with automatic features. These cameras were easy to use and cost less than the top models, so more hobbyists could enjoy them. They helped Pentax reach new photographers who were just learning.

• P5/P50 (1986–1989): Top model with more settings.
• P3/P30 (1985–1988): Simple design, like a point and shoot.
• P3n/P30n (1988–1990): Has a better grip and easier controls.
• P30t (1990–1997): This camera had a dial for choosing picture modes and stayed in stores for many years.

SF Series

The Pentax SF series are the first generation of autofocus cameras. They have motorized film advance.

The Canon EOS EF system, the best selling camera mount of all-time, was released the same year.

• SFX/SF1 (1987–1989): First autofocus with a built-in pop-up TTL flash.
• SFXn/SF1n (1989–1993): Updated with faster autofocus.
• SF7/SF10 (1988–1993): Smaller and simpler, targeting entry level needs.

Z Series / PZ Series

The second generation Pentax auto focus cameras were called the PZ series in North America and the Z series everywhere else.

They had automatic shooting modes and autofocus improvements ment to compete with higher end cameras.

• Z-10 (1991): Entry level camera.
• Z-1 (1991): First flagship for professional use.
• Z-20 (1992): Has a built-in flash and more shooting modes.
• Z-50 (1992): Has a film advance motor.
• Z-1P (1994): Second flagship with faster autofocus and improved controls.
• Z-5P (1994): Pro features in a smaller body.
• Z-70 (1995): Designed to be simple to use.

MZ/ZX Series

The Pentax MZ series were designed to be small and light, like the M series.

• MZ-S (2001–2006): Flagship with metal construction.
• MZ-3 (1997–2006): This camera was a favorite for enthusiasts because it had fast shutter speeds and classic dials for quick settings.
• MZ-5 / MZ-5n (1996–2001): Retro dials for shutter speed and exposure.
• MZ-10 (1996–2001): Entry level camera limited to picture modes.
• MZ-7 (1999–2001): Automatic camera, no manual controls.
• MZ-6 / ZX-L (2001–2006): Small body with a digital screen and custom settings.
• MZ-M (1997–2005): Manual focus camera.
• MZ-50 (1997–2001): Entry level with automatic scene modes.
• MZ-30 (1999–2005): Basically a point and shoot.
• MZ-60 (2002–2005): Simple controls designed for FA, F, and A series autofocus lenses.

*ist (35mm Film)

The *Pentax ist (2003–2006) was Pentax’s last 35mm film SLR. It did not sell well because it was released when the market was shifting to digital.

Naming confusion was another problem. It is easy to mix it up with Pentax’s DSLR, the *ist D.

Digital Cameras

*ist Digital Series

The Pentax *ist digital series are the first generation of DSLRs. They were designed to be small and light, with APS-C sensors.

Older manual focus K-mount lenses are backwards compatible.

• *ist D (2003–2006): Flagship with two control dials and CompactFlash cards.
• *ist DS (2004–2005): Smaller and uses SD memory cards.
• *ist DS2 (2005–2006): This upgraded version added a larger screen on the back to make viewing your photos easier.
• *ist DL (2005–2006): This was an affordable and lightweight model made with simple controls for beginners.
• *ist DL2 (2006): This final model gave beginner photographers a larger screen and an improved autofocus system.

K Series Digital

• Pentax K100D (2006–2007)
• Pentax K110D (2006–2007)
• Pentax K10D (2006–2008)
• Pentax K10D Grand Prix (limited edition) (2007)
• Pentax K100D Super (2007–2008)
• Pentax K200D (2008–2009)
• Pentax K20D (2008–2009)
• Pentax K-m (Pentax K2000 in U.S.) (2008–2009)
• Pentax K-7 (2009–2010)
• Pentax K-x (2009–2011)
• Pentax K-r (2010–2012)
• Pentax K-5 (2010–2012)
• Pentax K-01 (2012–2013)
• Pentax K-30 (2012–2013)
• Pentax K-5 II (2012–2014)
• Pentax K-5 IIs (2012–2014)
• Pentax K-50 (2013–2016)
• Pentax K-500 (2013–2014)
• Pentax K-3 (2013–2015)
• Pentax K-S1 (2014–2016)
• Pentax K-S2 (2015–present)
• Pentax K-3 II (2015–2018)
• Pentax K-1 (2016–2018)
• Pentax K-70 (2016–2022)
• Pentax KP (2017–2021)
• Pentax K-1 II (2018–present)
• Pentax K-3 III (2021–present)
• Pentax KF (2022–present)

Third Party Cameras Using the K-mount

Numerous cameras have utilized the K-mount over the years. Some notable ones include:

Notable Third Party K-Mount Lenses

These are some companies that make K-mount lenses.

• Access: 28 mm f2.8 P-MC Macro, 75–300 mm f5.6 PMC Zoom.
• Angenieux: 70–210 mm f3.5.
• Agfa: Agfa Color 50 mm f1.4.
• Arsat: PCS Arsat 35 mm f2.8 Shift Lens.
• Carl Zeiss Jena: 20 mm f4, 28 mm f2.8, 70–210 mm f4.5, 75–300 mm f4.5-5.6 ED IF MC Macro.
• Carl Zeiss: Introduced a line of lenses for the K-mount in 2008.