The Pentax Papers, part 2, K-mount 35mm SLRs, 1975 to 1980.
From the first K-mount K2 to the magnificent pro caliber Pentax LX.
By Jason Schneider
The M42 screw thread mount served Asahi Pentax very well for 16 years, from the brilliantly basic Asahi Pentax (AP) of 1957 to the impressive autoexposure Pentax ES II of 1973. It even became the de facto “standard mount” adopted by Ricoh, Fuji, Mamiya, Petri, Chinon, Cosina, Edixa, Kalimar, Zeiss—even Alpa (the Si 2000) and Olympus (the short-lived FTL). But by the time 1970s rolled around it was clear that a quicker changing, more precisely seating bayonet mount with additional flexibility for configuring mechanical linkages to control aperture and metering was the wave of the future. The result was the K-mount, which debuted in 1975 and is still used on the latest Pentax DSLRs.
Most diehard Pentax fans know that the M42 screw mount used on all Pentax 35mm SLRs from 1957 to 1973 was originally designed for and used on German-made Praktica SLRs. The M42 mount was first developed by Carl Zeiss at their Jena plant in 1938 at the request of the KW camera company for their Praktica line, which had previously used M40 (40 mm by 1 mm DIN). However, t was first used by the East German brands VEB Zeiss Ikon in the Contax S of 1949, and by KW in the Praktica of the same year. But did you know that the Pentax K-mount that debuted on the Pentax K2 of 1975 and is still used in its latest iteration on all current Pentax DSLRs, was also designed by Zeiss?! Originally invented by Zeiss for a planned alliance with Pentax, the K-mount was intended as the common lens mount for a proposed new series of cameras and lenses, but the plan never materialized, and the two companies parted ways on amicable terms. Result: Pentax retained rights to what became the K-mount and the rights to at least one lens design, the acclaimed 28mm f/2 SMC Takumar, which employs the same optical formula as the so-called “Hollywood” 28mm f/2 Zeiss Distagon.

The superb 28mm f/2 SMC Pentax lens is based on the famed 28mm f/2 Zeiss Distagon design, licensed to Pentax by mutual agreement.
The K-mount is a simple, sturdy 3-lobed bayonet introduced with the original Pentax K series of 1975 (the Pentax K2, KX, and KM). The lens locks into the camera with an approximately 70° clockwise turn (viewed from 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 the spring-loaded diaphragm open for viewing and focusing. When the shutter is released, so is this lever. This allows the diaphragm to close the aperture down to the set value while the shutter fires to make the exposure and open it up again after the shutter closes.
Pentax K2
The top-or-the-line model in the original Pentax K line of 1975, the Pentax K2 replaced the Pentax ES II screw mount autoexposure camera, and was the first Pentax to feature a vertical run metal focal plane shutter capable of a higher X-sync speeds (1-1/125 sec) than the horizontal running cloth shutters in the simultaneously released Pentax KM and KX. The K2 featured aperture priority autoexposure, as well as match needle manual metering like the KX, but unlike the KX the set aperture was not visible in the finder. The Pentax KM was basically a K-mount version of the Pentax Spotmatic F, with center-the-needle, open-aperture metering—a very nice camera indeed.

Top of the line Pentax K2, successor to the M42 mount ES II, was the flagship of the first group of K-mount Pentaxes released in 1975.
Both these linkages are arranged so that they are aligned and spring-loaded by the air of inserting the lens and turning it until it locks in place. Bodies equipped with the original K-mount include all members of 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 lenses. K-mount lenses can be used on all Pentax bodies, but are restricted to stopped down metering mode when used with KAF-mount bodies.
Pentax K2 Specifications
Film type: 135 (35mm)
Image size: 24mm x 36mm
Shutter: Vertical, metal focal plane (electronic or mechanical operation)
Shutter speeds (mechanical): 1/125 or Bulb
Shutter speeds (electronic): 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000
Flash sync: X sync at 1/125
Self-timer: 5 - 9 seconds
Viewfinder: Pentaprism with cross-microprism or split-image focusing screen, 0.88x magnification
Exposure meter: Silicon photo diode (SPD) cell, with aperture-priority, TTL metering, center-weighted
Meter switch: Meter is on when shutter is depressed halfway
Batteries: 1.5V S76E, MS76H or equivalent
Size: 144 x 92 x 57mm (W x H x D)
Weight: 680 g (24.2 oz) with no lens
K2 Other Features:
Depth-of-field preview
Auto exposure (aperture priority)
Exposure compensation (4×, 2×, 1×, ½×, ¼×)
Pentax KX
The Pentax KX was one of the three original K-mount cameras introduced by Pentax as a replacement for the Spotmatic family of screw mount cameras. The KX model was the “enthusiast” model, one step up from the basic KM with a more sensitive light meter, a wider ISO range, and a mirror lock-up. It had a match-needle exposure readout so that the shutter speed set was indicated in the viewfinder. The aperture set on the lens was visible in the viewfinder through a small window. Downside: the KX is the only Pentax where the wind lever must be pulled out slightly for the meter to work. This makes the camera difficult to use for left-eyed users. Fortunately, Pentax didn't repeat this questionable design on its later cameras.

Pentax KX with 55mm f/1.8 SMC Pentax lens. Aimed at enthusiasts, it had a more sensitive meter, a wider ISO range, and a mirror lock.
Pentax KX Specifications:
Maker: Asahi Pentax
Dates: 1975–1977
Variants: chrome, black, Motor
Camera Type: 35mm SLR
Focusing: manual
Lens mount: Pentax K
Shutter: Mechanical focal plane horizontal, rubberized cloth
from 1 to 1/1000 sec.
Exposure meter: TTL, open aperture,
center weighted using SPD cells. EV 1–18
Exposure modes: Manual 1-1/1000s, Bulb
ASA/ISO range: ISO 8 to 6400
Finder screen: fixed microprism
Flash shoe: fixed hot shoe contact for dedicated flash
Flash speed: 1/60
TTL Flash: no
Motor drive: Special model Motor KX
Battery: 2 × 1.5V (SR44, LR44 or equivalent)
Dimensions: 143 × 91.4 × 52.5 mm (W x H x D, body only
Weight: 631g w/o lens
Number produced: unknown
Pentax KM
Pentax offered the Pentax KM as a slightly less expensive alternative to the Pentax KX in 1975. This is arguably the camera the Pentax K1000 of 1976should have been, offering depth-of-field preview and a self-timer; two features missing on the wildly popular cheaper model. Nevertheless, the K1000, aimed at the lower end of the market, remained in production until 1997(!), was the standard “student camera” of its day and is still an excellent and affordable choice for today’s analog enthusiasts. The KM was essentially a Pentax Spotmatic F, but with a Pentax K-mount and slightly crisper styling. It was ultimately replaced by the diminutive Pentax MX.
This camera features a rubberized cloth focal plane shutter with speeds of 1 to 1/1000 sec and flash sync at 1/60 sec. The CdS metering system has a range of 3 to 18 EV (at ASA 100). Film speeds range from ASA 20 to 3200, and t’s powered by an available 1.5v silver oxide battery.

Pentax KM with 50mm f/2 SMC Pentax-M lens. Lower priced than the KX, it was basically a more stylish K-mount version of the Spotmatic F.
Pentax K2 DMD (1976-1980)
The flagship model of its era, the Pentax K2 DMD was a special “pro” version of the K2 that was compatible with a data back and a motor drive (hence DMD) Also, both the aperture value and any exposure correction factor are now visible in the viewfinder, and there’s a viewfinder blind to ensure correct automatic exposures when nobody is looking through the eyepiece. Finally, the K2 DMD was the first Pentax to feature an exposure memory lock.

Pentax K2 DMD with 55mm f/1.8 SMC Pentax lens. A pro-aimed version of the K2, it accepted a data back, motor drive, had an eyepiece blind.
All 5 above-mentioned members of the original Pentax K-series are solid, reliable, fine-performing cameras that are great choices for analog shooters, especially when fitted with their original excellent Pentax-branded Pentax or Takumar lenses in K-mount. Prices vary widely, but there are many bargains out there on the used market if you keep your eyes peeled, choose wisely, and buy from reputable sellers that offer return privileges.
M Series Pentax SLRs.
The Pentax M series is often seen as the company’s response to the so-called “Compact SLR Revolution” ushered in by the debut of the landmark ultra-compact Olympus OM-1 of 1973. The series consists of 7 models, the ME (1976-1980), the MX (1976-1985), the ME Super (1979-1984) the MV (1979-1982), the MV1 (1979-1982), the ME F (1981-1988), and the MG (1982-1985). All but the MX were based on the same basic metal chassis camera body and feature manual focusing and aperture-priority autoexposure. The MX, like the ME, is a tad smaller than an Olympus OM, but it was designed as a manual metering camera aimed at enthusiasts or pros, had its own set of accessories incompatible with other M-series models (which were marketed as broad-spectrum models) and was the only M-series Pentax with a depth of field preview.

Pentax ME with 50mm f/2 SMC Pentax-M lens. The smallest full-frame 35mm SLR ever, it sold very well despite having no manual mode.
The Pentax ME, widely credited as the smallest full frame 35mm SLR ever made, features aperture-priority automation only (no manual override), the ME Super was an ME with a manual metering mode, and the MG, MV, and MV1 were simplified versions of the original ME. The ME F, the first autofocus SLR in series production, used a dedicated Auto Focus 35-70mm f/2.8 Pentax zoom lens with a built-in contrast-detect AF system integrated with an AF motor, but it autofocused poorly and wasn’t a commercial success.

Pentax ME-F with dedicated 35-70mm f/2.8 Auto Focus Zoom lens was the first production AF SLR, but sadly it didn't autofocus very well.
Pentax ME and ME Super
The Pentax ME performs very well, has a huge viewfinder, and is smaller than its competitors (such as the Nikon EM), but weighs a moderate 16.2 ounces (body only) due to its metal construction. However, the only exposure control is via the exposure compensation dial. It’s a great camera to hand off to a novice but serious shooters should opt for the ME Super, basically the same camera but with a metered manual exposure option, the over/under LEDs serving as a correct exposure confirmation when they stop flashing. Both models are readily available on the top online auction sites at very attractive prices, typically under $100. The ME Super often runs a tad higher but is well worth the difference to serious vintage shooters.

Pentax ME Super with 50mm f/1.7 SMC Pentax-M lens. It added manual metering, making it a better choice than the ME for photo enthusiasts.
Pentax ME specifications
Maker: Asahi Pentax
Dates: 1976-1980
Variants: chrome, black, SE
Camera Type: 35mm SLR
Focusing: manual
Lens mount: Pentax K
Shutter: electronic control focal plane Seiko MFC-E,
metal curtains, vertical travel, speeds
from 8s to 1/1000 sec, mechanical 1/100 sec
Exposure meter: Gallium photo diode, TTL, open aperture,
center weighted
Exposure modes: aperture priority
ASA/ISO range: 12 to 1600
Finder screen: fixed
Flash shoe: fixed hot shoe
Flash speed: 1/100 sec.
TTL Flash: no
Motor drive: external winder ME I (1.5 fps) or ME II (2 fps)
Battery: 2×1.5V
Dimensions:
Size: 131 x 82.5 x 49.5 (w x H x D)
Weight: 460g w/o lens
Number produced: unknown
Pentax MX
The Pentax MX is a 35mm SLR produced by Asahi Optical Co, later known as Pentax, of Japan between 1976 and 1985. It was Pentax's flagship pro SLR until the introduction of the more advanced Pentax LX in 1980. Internally, the MX is essentially a smaller, lighter version of the manual metering Pentax KX and otherwise has little in common with other Pentax M-series models. The MX was designed as the mechanical counterpart of the remarkably successful entry-level Pentax ME. Solidly built, the MX features fully mechanical construction, including a mechanical, horizontal cloth focal plane shutter. Only the meteringsystem is dependent on batteries. The MX is all manual, lacking autoexposure modes such as aperture-priority, shutter-speed priority, or full program.

Pentax MX with 50mm f/1.7 SMC Pentax-M lens. Pentax's flagship pro model prior to the LX, this all mechanical jewel is now a cult classic.
In keeping with its status as an enthusiast/pro-aimed model, a wide range of accessories were produced for the MX, including the following interchangeable focusing screens:
SC1: ground glass, split image rangefinder plus microprism collar (standard)
SA1: ground glass, microprism patch
SA3: ground glass, microprism patch, for wide aperture lenses
SB1: ground glass, split image rangefinder
SD1: ground glass, cross collimator
SE: plain ground glass
SI: ground glass, axis indications
A data back, Dial Data MX, and a bulk film back were also produced, as were motorized winders; Winder MX (2 fps) and Motor MX (5 fps). The MX accepts all K-mount lenses except for the newer FA-J and DA lenses without aperture rings. Due to its complete lack of automatic functions, but excellent array of manual controls, the MX is often selected as a camera for photography students to hone their technique. The depth-of-field preview and self-timer are absent on the earlier mass market K1000, and the MX is considered a cult classic by many Pentax fans.
Pentax MX Specifications
Type: 35mm full-frame SLR camera with open-aperture center-weighted Through-The-Lens meter.
Lens mount: Pentax K bayonet.
Standard lenses: SMC Pentax 50mm f/1.2, SMC Pentax-M 40mm f/2.8. Wind lever action: 162-degree throw, 20-degree stand-off angle.
Film loading: New magic-needle quick/sure loading.
Automatic winder: MX body accepts Winder MX for up to approx. 2 fps (single-frame and consecutive exposure possible) and Motor Drive MX for up to approx. 5 fps (single-frame and consecutive exposure operation possible).
Exposure counter: Automatic reset type.
Exposure meter: Open-aperture, center-weighted Through-The-Lens meter, with GPD cells for fast light response, with tri-colored LED exposure read-out, rapid wind lever and shutter release button acting as meter switch.
Exposure range: EV 1 -19 (ASA 100, f/1.4), Film speed range: ASA 25 - 1600.
Power source: Two 1.5V silver oxide batteries (G13); LED's double as battery check lamp.
Back cover: Standard back with memo holder, interchangeable with Magazine Back MX, Dial Data MX for data recording on film .
Body size: 135.5mm x 82.5mm x 49.5mm (W x H x D)
Body weight 495g.
Standard lens: SMC Pentax-M 50mm f / 1.4
Shutter: Horizontal-run, rubberized silk focal-plane shutter; speeds from 1/1000 to 1 sec. plus B; shutter lock and "Cocked" indicator.
Flash synchronization FP and X-sync terminals, plus hot shoe; 1/60 sec. X synchronization.
Self-timer: Delays shutter release by 4 - 12 seconds; self-timer start button provided.
Viewfinder: Silver-coated pentaprism finder ; split-image microprism focusing screen (8 interchangeable screens); 95% of picture-taking area visible and 0.97x magnification with 50mm lens at infinity; -0.5 diopter eyepiece. Information viewfinder shows f/stop, shutter speed and tri- colored LED read-out dots.
Mirror and diaphragm: Instant return mirror and automatic diaphragm. Other features: Depth-of-field preview with self-timer lever. Film wind and rewind: Ratchet-type rapid wind lever, plastic-tipped for comfort.
The Pentax MX is the most sought after M-series Pentax by today’s analog enthusiasts and as a result it holds its vale remarkably well, You can snag a clean fully functional Pentax MX with 50mm f/1.7 or 50mm f/1.4 SMC Takumar lens for prices ranging from around $100 to $250, but pristine models tend to command prices at the upper end of that range, black finished ones even higher.
The Pentax LX: The best of the manual focus Pentaxes?
The Pentax LX was the most advanced manual focus Pentax. Launched in 1980 to celebrate the 60th anniversary of Asahi Optical Co. (thus the LX, 60 in Roman numerals), it was Asahi Pentax's contender for the professional segment of the 35mm SLR camera market, competing with such stalwarts as the Nikon F3 and Canon New F-1. Introduced in 1980, when the M-series models were still in production and in production until 1997, it’s slightly larger than the Pentax M cameras, but not as large the Pentax K2 DMD it replaced as the flagship Pentax. It’s well sealed against moisture and dust, has more interchangeable viewfinders and focusing screens than its rivals (including a super-bright S69 screen).
The Pentax LX employs an advanced in-body TTL OTF metering system that can read the light reflected off the film and first shutter curtain during the exposure (based on a Minolta patent that was used in the Olympus OM-2), and it displays the selected aperture and shutter speed in the finder. It provides aperture priority autoexposure and metered manual exposure, but neither programmed autoexposure (P mode, which first appeared on the Pentax Super-A), nor autofocus (AF). The LX has a horizontal travel titanium focal plane shutter with mechanical speeds of 1/75 sec to 1/2000 sec, manual settings from 1/2000 sec to 4-sec, and electronically controlled speeds of 1/60 sec to 125 sec, and has been widely praised for its reliability. The Pentax LX has a very sensitive SPD metering system (EV-6.5 to EV 20 at ISO 100), accepts a Winder LX and a 5 fps Motor Drive LX.

Pentax LX with 50mm f/1.4 SMC Pentax-A lens. Widely hailed as the best manual focus Pentax ever its coveted by both users and collectors.
Note: During its long 17-year production run the Pentax LX was updated at least three times. The latest revision has three visible differences compared to the earliest models: there are two white points missing on the front of the first shutter curtain; pressing the button that releases the viewfinder causes the light meter to turn on, and the shutter-lock switch features a new design. Several attempts to determine which serial numbers coincide with these design variations have so far proven inconclusive.
Pentax LX specifications
Type: 35mm full frame SLR
Manufacturer: Asahi Pentax, Japan
Film: standard 35mm cartridges, ISO 6 to 3200 (manual selection).
Lens mount: Pentax K bayonet.
Viewfinders: Interchangeable viewfinders; aperture visible in standard FA-1, FA-1W, FC-1, and FD-1 finders.
Displays: Tricolor display for TTL-measured shutter speeds, with green LEDs indicating hand-holdable speeds from 1/2000 sec to 1/30 sec, yellow LEDs as slow-speed warning from 1/15 sec to 4 sec, and red LEDs indicating overexposure or long exposure and "X"-sync flash-ready light with TTL and dedicated flash units; blue flag indicates automatic at "A" and manually selected shutter speeds.
Metering: SPD cell TTL center-weighted (60/40), metering off film plane, metering activated by lightly pressing shutter release button, EV -6.5 - 20 at ISO 100, f/1.4
Shutter: Hybrid electromechanical horizontal titanium focal plane shutter; speeds: mechanical, 1/2000-1/75 sec and electronic, 1/60-4 sec.
Exposure modes:
A: Aperture priority
M: Manual by selecting the shutter speed
X: flash sync (1/75 sec)
B: Bulb
Dimensions: 144.5 × 90 × 50mm (W x H x D), body with FA-1 finder.
Weight: 565g (19.9 oz.) with standard FA-1 finder.
Film transport: Manual wind, single stroke of 120 degrees or multiple short strokes to cock the shutter. Lever stand-off position at 25 degrees. Up to 5 fps with Motor Drive LX, also compatible with Winder LX.
Battery: 2x 1.5V alkaline or silver-oxide SR44/LR44, or 1×CR11108.
For a camera that was last made more than 25 years ago, the Pentax LX is held in very high esteem among users and collectors, resulting in used prices ranging from $275 to $450 for models in clean working condition.
If you hanker for a Pentax LX that really stands out from the crowd and have the wherewithal to afford it, here’s a trio of limited-edition gems:
Pentax LX Gold: In October 1981 a special limited edition of 300 LX cameras was produced to celebrate Pantax’s achievement of being the first manufacturer to produce ten million SLR cameras. On this version all metal parts are gold plated, the leather covering is brown skin, and the plastic parts are dark brown. The accompanying SMC Pentax 50mm f/1.2 Takumar lens is similarly finished with brown leather covering the focusing ring. The LX Gold came with a snazzy matching brown ever-ready case.

Pentax LX Special Edition "ILX" of 1981 in gold with gold 50mm f/1.2 SMC Pentax lens, original boxes, certificate of authenticity. It's pricey!
Pentax LX Titan: In September 1994 another limited-edition LX was created to celebrate 75th anniversary of Asahi Optical Co. Dubbed the LX Titan, it had natural titanium top housing and base plate, and it was manufactured in a run of 1,000 pieces. No special engraving was needed since the titanium shell was easily identifiable. A Special 75th Anniversary brown leather strap, a special brown box, and accessories made this limited-edition LX stand out. The LX Titan was only on sale in Japan at a price of 280,000 Yen. Serial numbers start from 7500001, up to 7501000.

Rare Pentax LX Titan 75th 1000 Limited Edition outfit included a special 75th Anniversary brown leather strap, a special box, and accessories.
The Millennium Model Y2K/2000 Special Edition LX: Surprise, surprise--this special-edition Pentax LX was produced in the year 2000. Like the LX Gold it came with a 50 mm f/1.2 Takumar lens, but this time in a special brushed aluminum finish.

Rare Unused in Box Millennium Pentax ILX 2000 with 50mm f/1.2 Special Lens in a special brushed aluminum finish. Gorgeous, but expensive!
You can snag a “Rare Unused in Box Pentax LX Titan 75th 1000 Limited” model with no lens for $2,499.99 plus $40 shipping from Japan, a “Rare Unused in Box LX 2000 with 50mm f/1.2 Special Lens” for $3,499.99 plus $80 shipping, or a “Pentax LX Limited Edition 18kt Gold with matching 50mm f/1.2 SMC Pentax lens (number 36 of 300 made) for $3,943.10 plus a piddling $8.40 shipping from the U.S. All are currently listed on eBay, so take your pick!
From the first K-mount K2 to the magnificent pro caliber Pentax LX.
By Jason Schneider
The M42 screw thread mount served Asahi Pentax very well for 16 years, from the brilliantly basic Asahi Pentax (AP) of 1957 to the impressive autoexposure Pentax ES II of 1973. It even became the de facto “standard mount” adopted by Ricoh, Fuji, Mamiya, Petri, Chinon, Cosina, Edixa, Kalimar, Zeiss—even Alpa (the Si 2000) and Olympus (the short-lived FTL). But by the time 1970s rolled around it was clear that a quicker changing, more precisely seating bayonet mount with additional flexibility for configuring mechanical linkages to control aperture and metering was the wave of the future. The result was the K-mount, which debuted in 1975 and is still used on the latest Pentax DSLRs.
Most diehard Pentax fans know that the M42 screw mount used on all Pentax 35mm SLRs from 1957 to 1973 was originally designed for and used on German-made Praktica SLRs. The M42 mount was first developed by Carl Zeiss at their Jena plant in 1938 at the request of the KW camera company for their Praktica line, which had previously used M40 (40 mm by 1 mm DIN). However, t was first used by the East German brands VEB Zeiss Ikon in the Contax S of 1949, and by KW in the Praktica of the same year. But did you know that the Pentax K-mount that debuted on the Pentax K2 of 1975 and is still used in its latest iteration on all current Pentax DSLRs, was also designed by Zeiss?! Originally invented by Zeiss for a planned alliance with Pentax, the K-mount was intended as the common lens mount for a proposed new series of cameras and lenses, but the plan never materialized, and the two companies parted ways on amicable terms. Result: Pentax retained rights to what became the K-mount and the rights to at least one lens design, the acclaimed 28mm f/2 SMC Takumar, which employs the same optical formula as the so-called “Hollywood” 28mm f/2 Zeiss Distagon.

The superb 28mm f/2 SMC Pentax lens is based on the famed 28mm f/2 Zeiss Distagon design, licensed to Pentax by mutual agreement.
The K-mount is a simple, sturdy 3-lobed bayonet introduced with the original Pentax K series of 1975 (the Pentax K2, KX, and KM). The lens locks into the camera with an approximately 70° clockwise turn (viewed from 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 the spring-loaded diaphragm open for viewing and focusing. When the shutter is released, so is this lever. This allows the diaphragm to close the aperture down to the set value while the shutter fires to make the exposure and open it up again after the shutter closes.
Pentax K2
The top-or-the-line model in the original Pentax K line of 1975, the Pentax K2 replaced the Pentax ES II screw mount autoexposure camera, and was the first Pentax to feature a vertical run metal focal plane shutter capable of a higher X-sync speeds (1-1/125 sec) than the horizontal running cloth shutters in the simultaneously released Pentax KM and KX. The K2 featured aperture priority autoexposure, as well as match needle manual metering like the KX, but unlike the KX the set aperture was not visible in the finder. The Pentax KM was basically a K-mount version of the Pentax Spotmatic F, with center-the-needle, open-aperture metering—a very nice camera indeed.

Top of the line Pentax K2, successor to the M42 mount ES II, was the flagship of the first group of K-mount Pentaxes released in 1975.
Both these linkages are arranged so that they are aligned and spring-loaded by the air of inserting the lens and turning it until it locks in place. Bodies equipped with the original K-mount include all members of 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 lenses. K-mount lenses can be used on all Pentax bodies, but are restricted to stopped down metering mode when used with KAF-mount bodies.
Pentax K2 Specifications
Manufacturer: Pentax
Film type: 135 (35mm)
Image size: 24mm x 36mm
Shutter: Vertical, metal focal plane (electronic or mechanical operation)
Shutter speeds (mechanical): 1/125 or Bulb
Shutter speeds (electronic): 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000
Flash sync: X sync at 1/125
Self-timer: 5 - 9 seconds
Viewfinder: Pentaprism with cross-microprism or split-image focusing screen, 0.88x magnification
Exposure meter: Silicon photo diode (SPD) cell, with aperture-priority, TTL metering, center-weighted
Meter switch: Meter is on when shutter is depressed halfway
Batteries: 1.5V S76E, MS76H or equivalent
Size: 144 x 92 x 57mm (W x H x D)
Weight: 680 g (24.2 oz) with no lens
K2 Other Features:
Depth-of-field preview
Auto exposure (aperture priority)
Exposure compensation (4×, 2×, 1×, ½×, ¼×)
Pentax KX
The Pentax KX was one of the three original K-mount cameras introduced by Pentax as a replacement for the Spotmatic family of screw mount cameras. The KX model was the “enthusiast” model, one step up from the basic KM with a more sensitive light meter, a wider ISO range, and a mirror lock-up. It had a match-needle exposure readout so that the shutter speed set was indicated in the viewfinder. The aperture set on the lens was visible in the viewfinder through a small window. Downside: the KX is the only Pentax where the wind lever must be pulled out slightly for the meter to work. This makes the camera difficult to use for left-eyed users. Fortunately, Pentax didn't repeat this questionable design on its later cameras.

Pentax KX with 55mm f/1.8 SMC Pentax lens. Aimed at enthusiasts, it had a more sensitive meter, a wider ISO range, and a mirror lock.
Pentax KX Specifications:
Maker: Asahi Pentax
Dates: 1975–1977
Variants: chrome, black, Motor
Camera Type: 35mm SLR
Focusing: manual
Lens mount: Pentax K
Shutter: Mechanical focal plane horizontal, rubberized cloth
from 1 to 1/1000 sec.
Exposure meter: TTL, open aperture,
center weighted using SPD cells. EV 1–18
Exposure modes: Manual 1-1/1000s, Bulb
ASA/ISO range: ISO 8 to 6400
Finder screen: fixed microprism
Flash shoe: fixed hot shoe contact for dedicated flash
Flash speed: 1/60
TTL Flash: no
Motor drive: Special model Motor KX
Battery: 2 × 1.5V (SR44, LR44 or equivalent)
Dimensions: 143 × 91.4 × 52.5 mm (W x H x D, body only
Weight: 631g w/o lens
Number produced: unknown
Pentax KM
Pentax offered the Pentax KM as a slightly less expensive alternative to the Pentax KX in 1975. This is arguably the camera the Pentax K1000 of 1976should have been, offering depth-of-field preview and a self-timer; two features missing on the wildly popular cheaper model. Nevertheless, the K1000, aimed at the lower end of the market, remained in production until 1997(!), was the standard “student camera” of its day and is still an excellent and affordable choice for today’s analog enthusiasts. The KM was essentially a Pentax Spotmatic F, but with a Pentax K-mount and slightly crisper styling. It was ultimately replaced by the diminutive Pentax MX.
This camera features a rubberized cloth focal plane shutter with speeds of 1 to 1/1000 sec and flash sync at 1/60 sec. The CdS metering system has a range of 3 to 18 EV (at ASA 100). Film speeds range from ASA 20 to 3200, and t’s powered by an available 1.5v silver oxide battery.

Pentax KM with 50mm f/2 SMC Pentax-M lens. Lower priced than the KX, it was basically a more stylish K-mount version of the Spotmatic F.
Pentax K2 DMD (1976-1980)
The flagship model of its era, the Pentax K2 DMD was a special “pro” version of the K2 that was compatible with a data back and a motor drive (hence DMD) Also, both the aperture value and any exposure correction factor are now visible in the viewfinder, and there’s a viewfinder blind to ensure correct automatic exposures when nobody is looking through the eyepiece. Finally, the K2 DMD was the first Pentax to feature an exposure memory lock.

Pentax K2 DMD with 55mm f/1.8 SMC Pentax lens. A pro-aimed version of the K2, it accepted a data back, motor drive, had an eyepiece blind.
All 5 above-mentioned members of the original Pentax K-series are solid, reliable, fine-performing cameras that are great choices for analog shooters, especially when fitted with their original excellent Pentax-branded Pentax or Takumar lenses in K-mount. Prices vary widely, but there are many bargains out there on the used market if you keep your eyes peeled, choose wisely, and buy from reputable sellers that offer return privileges.
M Series Pentax SLRs.
The Pentax M series is often seen as the company’s response to the so-called “Compact SLR Revolution” ushered in by the debut of the landmark ultra-compact Olympus OM-1 of 1973. The series consists of 7 models, the ME (1976-1980), the MX (1976-1985), the ME Super (1979-1984) the MV (1979-1982), the MV1 (1979-1982), the ME F (1981-1988), and the MG (1982-1985). All but the MX were based on the same basic metal chassis camera body and feature manual focusing and aperture-priority autoexposure. The MX, like the ME, is a tad smaller than an Olympus OM, but it was designed as a manual metering camera aimed at enthusiasts or pros, had its own set of accessories incompatible with other M-series models (which were marketed as broad-spectrum models) and was the only M-series Pentax with a depth of field preview.

Pentax ME with 50mm f/2 SMC Pentax-M lens. The smallest full-frame 35mm SLR ever, it sold very well despite having no manual mode.
The Pentax ME, widely credited as the smallest full frame 35mm SLR ever made, features aperture-priority automation only (no manual override), the ME Super was an ME with a manual metering mode, and the MG, MV, and MV1 were simplified versions of the original ME. The ME F, the first autofocus SLR in series production, used a dedicated Auto Focus 35-70mm f/2.8 Pentax zoom lens with a built-in contrast-detect AF system integrated with an AF motor, but it autofocused poorly and wasn’t a commercial success.

Pentax ME-F with dedicated 35-70mm f/2.8 Auto Focus Zoom lens was the first production AF SLR, but sadly it didn't autofocus very well.
Pentax ME and ME Super
The Pentax ME performs very well, has a huge viewfinder, and is smaller than its competitors (such as the Nikon EM), but weighs a moderate 16.2 ounces (body only) due to its metal construction. However, the only exposure control is via the exposure compensation dial. It’s a great camera to hand off to a novice but serious shooters should opt for the ME Super, basically the same camera but with a metered manual exposure option, the over/under LEDs serving as a correct exposure confirmation when they stop flashing. Both models are readily available on the top online auction sites at very attractive prices, typically under $100. The ME Super often runs a tad higher but is well worth the difference to serious vintage shooters.

Pentax ME Super with 50mm f/1.7 SMC Pentax-M lens. It added manual metering, making it a better choice than the ME for photo enthusiasts.
Pentax ME specifications
Maker: Asahi Pentax
Dates: 1976-1980
Variants: chrome, black, SE
Camera Type: 35mm SLR
Focusing: manual
Lens mount: Pentax K
Shutter: electronic control focal plane Seiko MFC-E,
metal curtains, vertical travel, speeds
from 8s to 1/1000 sec, mechanical 1/100 sec
Exposure meter: Gallium photo diode, TTL, open aperture,
center weighted
Exposure modes: aperture priority
ASA/ISO range: 12 to 1600
Finder screen: fixed
Flash shoe: fixed hot shoe
Flash speed: 1/100 sec.
TTL Flash: no
Motor drive: external winder ME I (1.5 fps) or ME II (2 fps)
Battery: 2×1.5V
Dimensions:
Size: 131 x 82.5 x 49.5 (w x H x D)
Weight: 460g w/o lens
Number produced: unknown
Pentax MX
The Pentax MX is a 35mm SLR produced by Asahi Optical Co, later known as Pentax, of Japan between 1976 and 1985. It was Pentax's flagship pro SLR until the introduction of the more advanced Pentax LX in 1980. Internally, the MX is essentially a smaller, lighter version of the manual metering Pentax KX and otherwise has little in common with other Pentax M-series models. The MX was designed as the mechanical counterpart of the remarkably successful entry-level Pentax ME. Solidly built, the MX features fully mechanical construction, including a mechanical, horizontal cloth focal plane shutter. Only the meteringsystem is dependent on batteries. The MX is all manual, lacking autoexposure modes such as aperture-priority, shutter-speed priority, or full program.

Pentax MX with 50mm f/1.7 SMC Pentax-M lens. Pentax's flagship pro model prior to the LX, this all mechanical jewel is now a cult classic.
In keeping with its status as an enthusiast/pro-aimed model, a wide range of accessories were produced for the MX, including the following interchangeable focusing screens:
SC1: ground glass, split image rangefinder plus microprism collar (standard)
SA1: ground glass, microprism patch
SA3: ground glass, microprism patch, for wide aperture lenses
SB1: ground glass, split image rangefinder
SD1: ground glass, cross collimator
SE: plain ground glass
SI: ground glass, axis indications
A data back, Dial Data MX, and a bulk film back were also produced, as were motorized winders; Winder MX (2 fps) and Motor MX (5 fps). The MX accepts all K-mount lenses except for the newer FA-J and DA lenses without aperture rings. Due to its complete lack of automatic functions, but excellent array of manual controls, the MX is often selected as a camera for photography students to hone their technique. The depth-of-field preview and self-timer are absent on the earlier mass market K1000, and the MX is considered a cult classic by many Pentax fans.
Pentax MX Specifications
Type: 35mm full-frame SLR camera with open-aperture center-weighted Through-The-Lens meter.
Lens mount: Pentax K bayonet.
Standard lenses: SMC Pentax 50mm f/1.2, SMC Pentax-M 40mm f/2.8. Wind lever action: 162-degree throw, 20-degree stand-off angle.
Film loading: New magic-needle quick/sure loading.
Automatic winder: MX body accepts Winder MX for up to approx. 2 fps (single-frame and consecutive exposure possible) and Motor Drive MX for up to approx. 5 fps (single-frame and consecutive exposure operation possible).
Exposure counter: Automatic reset type.
Exposure meter: Open-aperture, center-weighted Through-The-Lens meter, with GPD cells for fast light response, with tri-colored LED exposure read-out, rapid wind lever and shutter release button acting as meter switch.
Exposure range: EV 1 -19 (ASA 100, f/1.4), Film speed range: ASA 25 - 1600.
Power source: Two 1.5V silver oxide batteries (G13); LED's double as battery check lamp.
Back cover: Standard back with memo holder, interchangeable with Magazine Back MX, Dial Data MX for data recording on film .
Body size: 135.5mm x 82.5mm x 49.5mm (W x H x D)
Body weight 495g.
Standard lens: SMC Pentax-M 50mm f / 1.4
Shutter: Horizontal-run, rubberized silk focal-plane shutter; speeds from 1/1000 to 1 sec. plus B; shutter lock and "Cocked" indicator.
Flash synchronization FP and X-sync terminals, plus hot shoe; 1/60 sec. X synchronization.
Self-timer: Delays shutter release by 4 - 12 seconds; self-timer start button provided.
Viewfinder: Silver-coated pentaprism finder ; split-image microprism focusing screen (8 interchangeable screens); 95% of picture-taking area visible and 0.97x magnification with 50mm lens at infinity; -0.5 diopter eyepiece. Information viewfinder shows f/stop, shutter speed and tri- colored LED read-out dots.
Mirror and diaphragm: Instant return mirror and automatic diaphragm. Other features: Depth-of-field preview with self-timer lever. Film wind and rewind: Ratchet-type rapid wind lever, plastic-tipped for comfort.
The Pentax MX is the most sought after M-series Pentax by today’s analog enthusiasts and as a result it holds its vale remarkably well, You can snag a clean fully functional Pentax MX with 50mm f/1.7 or 50mm f/1.4 SMC Takumar lens for prices ranging from around $100 to $250, but pristine models tend to command prices at the upper end of that range, black finished ones even higher.
The Pentax LX: The best of the manual focus Pentaxes?
The Pentax LX was the most advanced manual focus Pentax. Launched in 1980 to celebrate the 60th anniversary of Asahi Optical Co. (thus the LX, 60 in Roman numerals), it was Asahi Pentax's contender for the professional segment of the 35mm SLR camera market, competing with such stalwarts as the Nikon F3 and Canon New F-1. Introduced in 1980, when the M-series models were still in production and in production until 1997, it’s slightly larger than the Pentax M cameras, but not as large the Pentax K2 DMD it replaced as the flagship Pentax. It’s well sealed against moisture and dust, has more interchangeable viewfinders and focusing screens than its rivals (including a super-bright S69 screen).
The Pentax LX employs an advanced in-body TTL OTF metering system that can read the light reflected off the film and first shutter curtain during the exposure (based on a Minolta patent that was used in the Olympus OM-2), and it displays the selected aperture and shutter speed in the finder. It provides aperture priority autoexposure and metered manual exposure, but neither programmed autoexposure (P mode, which first appeared on the Pentax Super-A), nor autofocus (AF). The LX has a horizontal travel titanium focal plane shutter with mechanical speeds of 1/75 sec to 1/2000 sec, manual settings from 1/2000 sec to 4-sec, and electronically controlled speeds of 1/60 sec to 125 sec, and has been widely praised for its reliability. The Pentax LX has a very sensitive SPD metering system (EV-6.5 to EV 20 at ISO 100), accepts a Winder LX and a 5 fps Motor Drive LX.

Pentax LX with 50mm f/1.4 SMC Pentax-A lens. Widely hailed as the best manual focus Pentax ever its coveted by both users and collectors.
Note: During its long 17-year production run the Pentax LX was updated at least three times. The latest revision has three visible differences compared to the earliest models: there are two white points missing on the front of the first shutter curtain; pressing the button that releases the viewfinder causes the light meter to turn on, and the shutter-lock switch features a new design. Several attempts to determine which serial numbers coincide with these design variations have so far proven inconclusive.
Pentax LX specifications
Type: 35mm full frame SLR
Manufacturer: Asahi Pentax, Japan
Film: standard 35mm cartridges, ISO 6 to 3200 (manual selection).
Lens mount: Pentax K bayonet.
Viewfinders: Interchangeable viewfinders; aperture visible in standard FA-1, FA-1W, FC-1, and FD-1 finders.
Displays: Tricolor display for TTL-measured shutter speeds, with green LEDs indicating hand-holdable speeds from 1/2000 sec to 1/30 sec, yellow LEDs as slow-speed warning from 1/15 sec to 4 sec, and red LEDs indicating overexposure or long exposure and "X"-sync flash-ready light with TTL and dedicated flash units; blue flag indicates automatic at "A" and manually selected shutter speeds.
Metering: SPD cell TTL center-weighted (60/40), metering off film plane, metering activated by lightly pressing shutter release button, EV -6.5 - 20 at ISO 100, f/1.4
Shutter: Hybrid electromechanical horizontal titanium focal plane shutter; speeds: mechanical, 1/2000-1/75 sec and electronic, 1/60-4 sec.
Exposure modes:
A: Aperture priority
M: Manual by selecting the shutter speed
X: flash sync (1/75 sec)
B: Bulb
Dimensions: 144.5 × 90 × 50mm (W x H x D), body with FA-1 finder.
Weight: 565g (19.9 oz.) with standard FA-1 finder.
Film transport: Manual wind, single stroke of 120 degrees or multiple short strokes to cock the shutter. Lever stand-off position at 25 degrees. Up to 5 fps with Motor Drive LX, also compatible with Winder LX.
Battery: 2x 1.5V alkaline or silver-oxide SR44/LR44, or 1×CR11108.
For a camera that was last made more than 25 years ago, the Pentax LX is held in very high esteem among users and collectors, resulting in used prices ranging from $275 to $450 for models in clean working condition.
If you hanker for a Pentax LX that really stands out from the crowd and have the wherewithal to afford it, here’s a trio of limited-edition gems:
Pentax LX Gold: In October 1981 a special limited edition of 300 LX cameras was produced to celebrate Pantax’s achievement of being the first manufacturer to produce ten million SLR cameras. On this version all metal parts are gold plated, the leather covering is brown skin, and the plastic parts are dark brown. The accompanying SMC Pentax 50mm f/1.2 Takumar lens is similarly finished with brown leather covering the focusing ring. The LX Gold came with a snazzy matching brown ever-ready case.

Pentax LX Special Edition "ILX" of 1981 in gold with gold 50mm f/1.2 SMC Pentax lens, original boxes, certificate of authenticity. It's pricey!
Pentax LX Titan: In September 1994 another limited-edition LX was created to celebrate 75th anniversary of Asahi Optical Co. Dubbed the LX Titan, it had natural titanium top housing and base plate, and it was manufactured in a run of 1,000 pieces. No special engraving was needed since the titanium shell was easily identifiable. A Special 75th Anniversary brown leather strap, a special brown box, and accessories made this limited-edition LX stand out. The LX Titan was only on sale in Japan at a price of 280,000 Yen. Serial numbers start from 7500001, up to 7501000.

Rare Pentax LX Titan 75th 1000 Limited Edition outfit included a special 75th Anniversary brown leather strap, a special box, and accessories.
The Millennium Model Y2K/2000 Special Edition LX: Surprise, surprise--this special-edition Pentax LX was produced in the year 2000. Like the LX Gold it came with a 50 mm f/1.2 Takumar lens, but this time in a special brushed aluminum finish.

Rare Unused in Box Millennium Pentax ILX 2000 with 50mm f/1.2 Special Lens in a special brushed aluminum finish. Gorgeous, but expensive!
You can snag a “Rare Unused in Box Pentax LX Titan 75th 1000 Limited” model with no lens for $2,499.99 plus $40 shipping from Japan, a “Rare Unused in Box LX 2000 with 50mm f/1.2 Special Lens” for $3,499.99 plus $80 shipping, or a “Pentax LX Limited Edition 18kt Gold with matching 50mm f/1.2 SMC Pentax lens (number 36 of 300 made) for $3,943.10 plus a piddling $8.40 shipping from the U.S. All are currently listed on eBay, so take your pick!
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