|Type||SLR camera for 120/220 roll film|
Originally debuting in 1965 as a prototype dubbed the Pentax 220. Since then and with improvements, it finally released in 1969 as the Asahi Pentax 6×7, as well as the Honeywell Pentax 6×7 for the American import market. It would later receive a few changes and dubbed the Pentax 67. It was a SLR medium format system cameras for 120 & 220 film. It resembles a traditional 35mm SLR camera with interchangeable viewfinder and lens, but is considerably bigger and heavier, weighing 2.3 kilograms (5.1 lb) with plain prism and standard lens; perhaps inspired by the 1957 East German 6×6 KW Praktisix and its successor, the Pentacon Six, although the horizontal SLR concept can be traced back to the 1933 Ihagee VP Exakta. The Pentax 6×7 has its own dual bayonet lens mount, and a wide range of interchangeable Takumar lenses exist. More than forty years after the original camera introduction a wide selection of lenses was still available, together with the latest Pentax 67II.
The following models has been issued:
- Asahi Pentax 6×7 is the original model that was introduced in 1969
- Asahi Pentax 6×7 (MU) with a mirror-up mechanism came in 1976
- Pentax 67 is an improved version launched in 1990
- Pentax 67II is the current model as of 2010, on sale since 1999:
The Pentax 6×7, designated product model number of 23400 by Asahi Pentax, is similar to any traditional 35mm SLR camera except in size. The hefty camera with a general dimension body of 7.25"x 4.5"x 3.75" / 18cm x 11cm x 9.5cm and with the standard prism and 105mm lens would bring it to 7.5" x 5.75" x 6.5" / 18cm x 14.5cm x 17cm. As naming conventions implies, the 6 x 7 indicates that this is a medium format camera and the negative produced is 6cm by 7cm (actual format 56mm X 70mm). It has the ability to use either the 120 or 220 roll film, which produces ten or twenty respectively (twenty-one for the 1969 version). A small slotted selector on the right-hand side next to the frame counter of the camera selects the film type (properly operated when film door is opened), and also the film pressure plate inside has positions for either type, the thickness of the films being different. The pressure plate also maintains film flatness in this horizontal design during exposure, aiding the extreme sharpness across the entire image for which the camera is renowned. Other systems use film tension alone, or against rails at the film's edge, in more compact vertical-feed magazines found in 6×6 or 6×4.5 formats. The standard equipment includes the Super Takumar and later the Super-Multi-Coated TAKUMAR/6×7 1:2.4 f=105 lens and the removable pentaprism finder that shows (90% of actual area) exactly the exposed image.
Mechanical details: The camera is almost completely battery dependent (small exception below), power is provided by a mercury PX28 (originally specified), but equal substitutes are silver-oxide PX28S/4SR44. Although powered by a battery, the mirror and cloth curtains are mechanically driven, the timing of the two actions are electrically governed by timing transistors and a magnet. Also, the operation of the shutter is not normally possible without film properly loaded, however, a provision for shutter testing is possible when the film counter dial is rotated away from the empty position while the film door is open and then by closing the film door while still holding the dial will then facilitate the unlocking of the advance mechanism and operation of the shutter. The frame counter is incremented only while there is film passing through the 'main roller' or "counter roller" next to the take-up spool in the camera. The camera disengages the "transport system" when the counter dial has reached the last frame or when the counter has returned to the zero or start position. The automatic frame counter resets only if the shutter is released before opening the back. Because a battery must power the timing, the loss of adequate voltage means the camera halts after the mirror is raised, but will not complete its cycle and the curtain release will disengage. To drive the mirror to finish the cycle, a small button located flush on the right-hand camera front, just below the shutter-release button, is provided for restarting of the mirror/shutter cycle. Depressing the shutter release once more will release the cycles. The shutter release button is standard threaded for bulb or cable releases or the use of a large accessory button. The fingernail operated latch to the left lower side releases the film door for loading. The film spools are secured by the pins and slot shaped opening at either end to the spool. The camera has two twist-lock cams that turn and pull out to open. The left side for the unexposed roll and the right side, known as the 'take-up'. Because of the arrangement differences of the 120 and 220 start length of paper, the indicated starting points are marked above the film plane for lining up of the start marks for the film. The film advance system is a tension/friction type, the film source side being a tension brake and the take-up side torque/slip clutch. This system allows enough slip and movement to accurately space each frame from the beginning of the roll to the end as well as some give in the system to regulate a lock to open and allow the shutter to fire. This slip systems also has caused some criticism in durability for early models as it would gain slippage over time causing frame spacing issues as well as disengaging the shutter. The frame counter system tied to the counter roller operates the automatically reset of the counter (returns to start) whenever the back is opened as well as sets the regulating of the next frame.
Later Improvements: Changes to the advance lever angle from a tipped out to a curled inward and the trim shroud at back of the finder bay had a matching scallop for the new lever design to rest upon, this appeared about late 1972. As well were changes to the spool release mechanism, where it was an improvement from a checkered friction operated surface to a more convenient flip handled method and the center posts that held the film spools lost their angled profile for a more controversial straighter angle that caused some difficulty in speed of spool alingment that prompted some to seek services to custom grind the posts.
In 1976, to control the induced camera vibrations caused by the upward movement of the large mirror to a sudden stop, a mirror release mechanism was introduced. By sliding upwards the mirror-up switch on the right hand side of the mirror housing, it allowed a bypass of the mirror release from the shutter trip cycle. This allowed the mirror to fully raise and then hold, allowing then the shutter release cycle still be at the ready. Unfortunately, this also activated the main power switch that was mechanically tied to the mirrors' main gear action and until the depressing of the shutter release to completes the exposure, the power to the circuits remain on and would drain the battery over time. Even with this one negative aspect to the Mirror-Lock-Up modification, it would still become a standard feature in later productions.
At about the same time as the availability of the mirror-up or MLU feature was the necessity of changes to the counter and other key components in the advance mechanism. Pentax would phase out the parts compatible with the first release in favor of improved and more durable parts that would later become standard in the 67 badged models officially by mid 1986.
Lesser known for the later original 6×7 was a special factory modification at would allow the bypass of part of the frame counter mechanism (duality-prevent lever) for deliberate double exposures, though not many were made with this feature.
Another modification was a non-powered bulb exposure. This was a popular request from astronomers that needed the camera to expose for times greater that the batteries could allow. The demand for this modification was reduced when the availability of an adapter plate should then override the need for a battery and force the shutters to lock open and release by simple using two cable releases.
Polaroid Back/Foscher adapted bodies were a non-factory modification and was usually applied by authorized service centers. A familiar tool for studio photographers and later users would obtain a removable hinge version making it possible to switch out of the Foscher back to a normal pressure plate for roll film.
Other changes were to the frame counting cam that shorten the 220 film frame count from 21 to 20 and the 120 mode remained the same. This reduction was at the same time necessary when the new version of the 'clutch' plate to improve durability was released.
A minor change of color lens release switches from chrome to black. Due to these changes over time, some reports of mixed and matched factory release bodies existed.
Lenses and accessories: A wide range of lenses are available for this camera. The first lenses made available had a standard multi-coating and named "Super-Takumar" and after the release of the improved 7 layer coating they would be engraved "Takumar Super-Multi-Coated" and eventually the latest would abandon the Takumar in favor of Pentax and consolidate the coating name to SMC. Most of the lenses are "Auto-Aperture" type to allow for the brightest viewing and focussing of the lens for composition of the subject. The exceptions are: The 75mm Shift due to the manner that the base must slide out of direct alignment to the forward elements that the linkages for the Auto-Aperture is not possible. The 120mm Soft Focus due to its dual aperture system. The 600mm & 800mm due to their "Rach and Pinion" focus that it is not possible to have linkages to the Auto-Aperture. The 1000mm being a catadioptric lens that it is not possible to have an aperture.
Two leaf shuttered lenses were also made available, first the 90mm 2.8 and later a 165mm 2.8 that both allowing flash sync at all speeds, thereby solving many mirror and shutter vibration problems.
The Through-The-Lens (TTL) metering pentaprism viewfinder is a popular accessory and included a knurled ring that is slipped over the body's shutter speed dial to allow for easy operation of the shutter dial when the TTL is installed. The TTL Pentaprism is the same coverage as the non-metered with a coverage of 90% of frame and has a sensitivity pattern of 60% center-weight and 30% inner field sensitivity. Metering possible in two modes: Normal was in 'AUTO' mode where the lens is fully opened and adjustments are read from the coupled index of the TTL to the chain and index shuttle on the body. In 'MAN' mode the lens is allowed to stop-down and the light is directly measured. As did the body receiving improvements over time, so did the TTL have some changes. Although the image coverage remained unchanged, the type of metering and the circuitry received some upgrades. CdS (cadmium sulfide) to Gpd (gallium photo diode) photo cells and a two part circuit to a single board to improve response time and reliability. The early version is identified by the single marked 'ON' switch and the meter needle starts from UP to down and the later model has a 'ON' & 'OFF' marked switch and the meter needle starts from bottom to top. The later model would also have the soul PENTAX badge by 1986.
Two Waist-Level finders are available; a collapsible model that compactly folds almost flush with the top of the body and a fixed or rigid finder often called the Chimney finder. Both finders provided a 100% view of the frame. A special viewfinder was available for the Pentax 6x7 Marine Housing when the camera was to be used underwater.
Along with the standard microprism center focusing screen, four other focusing screens could be refitted in to the body (plain, gridded, grid with microprism, split-image as well as the standard). Due to the fact that installation of a screen required a qualified technician and he had to calibrate the screens into the camera, it is rare to find these variations of screens. The microprism screen adequate or usable down to f4.5 lenses, however, the more desired split screen could be used with lenses down to f5.6 made this a very coveted version.
Another separately available accessory is the distinctive left-hand grip with accessory shoe. Many manufacturers offer accessory grip or "action grips" such as Kowa, Bronica, Mamiya and Hasselblad the Pentax grip is arguably an iconic accessory for the camera. It attaches to the two lugs/posts at the front of the camera and is secured by tightening a finger-operated bolt onto a stud found at center. The grip is removed by untightening and lifting the bolt to slide off in a downward direction to allow the lugs to clear the keyhole slots.
Quick Focus Ring A & B
Rigid Bayonet Hoods Pinch on Hoods
Cold Weather Battery Holder
Along with the availability macro lenses for close work, a selection of extension tubes and in both the standard bayonet and the outer bayonet were available as well. As well as a compact and convenient variable extension was also available. For more flexibility was bellows system and also slide copier accessory.
Pentax 6×7 lenses feature the ability to accept both standard threaded filters and also Pentax bayonet filters that are available in standard and SMC versions.
Current and earlier lenses (as indicated) for the cameras as of November 2011: 
♣ Older/Original version (pre-updated optical design); ♦ Also existing as first release version, Takumar (non-SMC or pre-SMC)
- SMC PENTAX 67 45mm f4
- SMC TAKUMAR 6x7 55mm f3.5♣ ♦
- SMC PENTAX 6x7 55mm f4♣
- SMC PENTAX 67 55mm f4
- SMC PENTAX 67 75mm f2.8 AL
- SMC PENTAX 67 75mm f4.5
- SMC PENTAX 67 90mm f2.8
- SMC PENTAX 67 105mm f2.4 ♦
- SMC TAKUMAR 6X7 150mm f2.8♣ ♦
- SMC PENTAX 67 165mm f2.8
- SMC TAKUMAR 6x7 200mm f4♣ ♦
- SMC PENTAX 67 200mm f4
- SMC PENTAX 67 300mm f4♣
- SMC PENTAX 67 300mm f4 ED IF M*
- SMC TAKUMAR 6X7 400mm f4♣
- SMC PENTAX 67 400mm f4 ED IF
- SMC PENTAX 67 500mm f5.6
- SMC PENTAX 67 600mm f4 ♦
- SMC PENTAX 6X7 800mm f4♣ ♦
- SMC PENTAX 67 800mm f6.7 ED IF
- SMC PENTAX 6X7 1000mm f8 Mirror
- SMC PENTAX 67 Fish-Eye 35mm f4.5
- SMC PENTAX 6X7 Shift 75mm f4.5
- SMC PENTAX 6x7 LS 90mm f2.8
- SMC PENTAX 67 Macro 100mm f4 & smc LIFE-SIZE CONVERTER
- SMC PENTAX 67 Soft 120mm f4
- SMC PENTAX 67 Macro 135mm f4
- SMC PENTAX 67 LS 165mm f4
- SMC PENTAX 67 55mm - 100mm f4.5
- SMC PENTAX 67 90mm - 180mm f5.6
- PENTAX 67 Rear Converter 1.4×
- PENTAX 67 Rear Converter 2×
- PENTAX 67 Rear Converter T5-1.4×
- Ivor Matanle (1996). Collecting and using Classic SLRs. Thames & Hudson, London. ISBN 0-500-27901-2.
- James M. and Joan C. McKeown (2004). McKeown's price guide to antique classic Cameras, 12th Ed. Centennial Photo Service, Grantsburg. ISBN 0-931838-40-1.
- Pentax Subsidiary of HOYA publication
- Günther Kadlubek, Rudolf Hillebrand (2004). Kadlubeks Kamera-Katalog 5th Ed. Verlag Rudolf Hillebrand, Neuss. ISBN 3-89506-995-7.
- Asahi Optical sales literature and User Manuals.
- Pentax 67 home page: http://www.pentax.jp/english/products/filmcamera/lens/index672_list.html
Media related to Pentax 6x7 at Wikimedia Commons