Finding a Film Camera Home for M42 Lenses

Originally developed before WWII, the M42 lens mount was, for a time, a standard shared among multiple camera body manufacturers starting during the late 1940s. By the early 1970s, this coalition began to fall apart with each major manufacturer developing their own proprietary versions of M42 lenses to work with their own open-aperture light metering systems. By the mid-1970s, with 35mm SLR camera technology rapidly advancing, M42 bodies were on their way out. Because no truly “modern” M42 camera body was ever produced, there has always been much debate about what the “best” body was or is. None of them is the “best,” but some are better than others.

M42 technology evolved in five basic generations. The first generation (1938) included simple screw-in lenses with no mechanical linkage between the lens and the camera body. The second generation (1956) introduced auto-diaphragm lens operation which permits the lens aperture to be held wide open for easier focusing and then upon tripping the shutter, the camera would automatically stop down to the taking aperture. The third generation (1964) combined the auto-diaphragm function with stop-down TTL light metering. The fourth generation (1968) employed auto-diaphragm operation but also included an extra mechanical or electrical linkage that communicated the lens aperture to the camera body for one-step TTL light metering purposes. The final generation (1971) incorporated auto-diaphragm operation, the extra linkage, and an electronic shutter that permitted aperture-priority exposure. Apart from these, during the early 1970s, Cosina and Chinon developed a separate system that permitted a primitive aperture-priority autoexposure with every auto-diaphragm M42 lens. Here is a list of most M42 camera bodies listed by generation.

First Generation: The first generation had its birth before WWII but became commercially available starting in the late 1940s. Famous cameras from this period included the Contax S (1949), the original “Praktica” (1949), the Asahiflex (1952), and the Praktina FX (1953). These cameras came in various configurations and with and without pentaprisms. Their operation was simple: M42 lenses would just screw into the body. Best practice would be to focus at the widest aperture, and then physically stop down to taking aperture to take the shot. Of course, stopping down the lens would darken the viewfinder, making it nearly impossible to focus at the actual taking aperture (say, at apertures smaller than f/4).

Second Generation: During 1956, Contax of East Germany introduced the “F,” which had the ability to hold the aperture wide open regardless of the aperture set on the lens. However, this ability required the use of not-yet-to-market “auto-diaphragm” M42 lenses that contained a “stop-down” pin. Other notable cameras in this generation included the Asahi Pentax K and the Praktica FX3.

Third Generation: This generation fully adopted auto-diaphragm operation and combined it with TTL light metering. However, M42 camera manufacturers created an awkward, two-step procedure for bodies to combine the two concepts. Because the lenses could not communicate the selected aperture with the camera’s light meter, an external button or switch was added to the camera body that, while pressed, temporarily “stopped down” the lens so that the body could take a light meter reading at the actual taking aperture. You then fiddle with the aperture and/or shutter speed until the “match-needle” in the viewfinder was in the correct spot. After releasing the external button or switch, the light meter would shut off and the aperture would return to wide open so you can frame and re-focus if necessary. Every major M42 SLR manufacturer (Pentax, Yashica, Praktica, Fujica, Chinon, Zenit, etc.) produced zillions of these cameras from the mid-1960s to the late 1970s (with certain models produced into the late 1980s), which now litter closets, drawers, and second-hand stores all over the world. In addition to their cumbersome operation, most of these cameras were generally heavier, had fairly dark viewfinders even with faster lenses, and used now-obsolete batteries.

During 2003, Voigtlander (Cosina) introduced a final “third generation” M42 camera body, the Bessaflex TM. In conjunction with the Bessaflex, Zeiss produced in M42 mount (“ZS” lenses) some of its excellent contemporary manual-focus lenses it was also making in Nikon and Canon mounts and Voigtlander introduced a nice redesigned 58mm f/1.4 inspired by the legendary 1960s Topcon lens. The mechanical-shutter Bessaflex had some nice features, like a beautifully-bright viewfinder and a top shutter speed of 1/2000. Like other third-generation M42 bodies, the Bessaflex requires the activation of an external stop-down switch to activate the TTL light meter and has no autoexposure capability.

The Pentacon Super: During the mid-1960s, after an unusually long development period, East German engineers developed a solution for open-aperture metering with M42 lenses without a manual stop-down step in the form of the 1968 Pentacon Super. Pentacon’s solution to open-aperture metering at different f-stops was to introduce a new line of M42 lenses that contained a second pin towards the outside of the lens that would interact with a curved piece of metal around the body’s lens mount. With the use of a removable, battery-powered prism (kind of like the Pentacon Six), the body could hold the lens wide-open and then meter the scene at the actual selected f-stop through a match needle system in the viewfinder. The Super’s metered prism could also display both the selected shutter speed and aperture in the viewfinder. Unfortunately, the Super was an extremely expensive camera at the time, could only be used to its full potential with a handful of specially-designed Carl Zeiss Jena lenses, and was ultimately produced in relatively small numbers.

Fourth Generation: Like the Pentacon Super, the fourth generation used extra linkages that would permit the lens to communicate the selected aperture for the purposes of light metering without the lens having to physically stop down. Besides the Super, the first to market with this technology was the 1969 “Praktica LLC.” Praktica used electrical, rather than mechanical, contacts to accomplish the extra lens-camera connection. This system was not “autoexposure” as it still required the manipulation of the both shutter speed and aperture so that a needle in the viewfinder sat in the correct place. Other examples of this generation include the 1971 Zeiss Ikon SL706, the 1972 Fujica ST-801, and the 1973 Pentax Spotmatic F. Most of these cameras also included a stop-down lever or switch so that you could use any manufacturer’s auto-diaphragm lenses in “third generation” mode.

Fifth Generation: During 1971, Pentax was first to market in the final generation of M42 cameras with its electronic-shutter “ES,” the first M42 camera capable of aperture-priority autoexposure, which of course means that you set the aperture and the camera can automatically set the appropriate shutter speed. This required the use of a “Super-Multi-Coated” Pentax lens with an “open aperture reading pin.” Other fifth generation aperture-priority models included the 1973 Pentax ES II, the 1974 Fujica ST-901 and the 1977 Praktica EE2. There were other models from this generation that employed shutter-speed priority autoexposure, like the 1976 Ricoh Auto TLS and the 1978 Exakta FE 2000. Again, each system required proprietary lenses for the autoexposure to operate in either aperture or shutter priority modes.

The Cosina/Chinon System: During the early 1970s, Cosina and Chinon introduced an interesting alternative system that allowed a primitive aperture-priority autoexposure with all auto-diaphragm M42 lenses, regardless of manufacturer. The technical solution was clever, but not necessarily revolutionary, and did not require the addition of any proprietary connections between the body and the lens. When mounting an M42 lens set to “A” on the diaphragm, the camera could be focused at an open aperture. When taking a photo, if the shutter button itself were pushed half-way down, the camera would stop the lens down to the taking aperture to meter the scene (thus darkening the viewfinder temporarily while the shutter button is half-depressed). The viewfinder would then display the shutter speed that would be automatically used if that aperture were selected. To take the photo, a full depress would instantaneously stop the lens down to the selected aperture and fire the shutter. The resulting stop down action happens so quickly that you don’t even notice it. Essentially, the bodies combined the traditional second-generation metering switch and shutter button into the same mechanism. The models equipped with this technology included the Cosina Hi-Lite EC (1972), the Cosina High Lite ECL (1976), the Chinon CE-II (1976), and the Chinon CE-3 (1978). Cosina, Chinon, and Zenit also used this shutter-button “stop-down” mechanism for a variety non-AE cameras.

So, what is the “best” M42 SLR camera body? The true answer is a bit complicated because it depends on how much work you want to do to take a 35mm photo and what kind of M42 lenses you want to use. I am generally not a fan of any of the first, second, or third generation of M42 bodies because the Cosina/Chinon system and the fifth generation systems are just easier to use. If you want a M42 camera to operate like a swiss army knife, to have full functionality with all auto-diaphragm M42 lenses, to have the option of aperture-priority autoexposure, to display the shutter speeds in the viewfinder, to use common modern batteries, to have an exposure lock function, and to be able to use a motor drive, my answer would be the Chinon CE-3. If you do not mind throwing real money at a camera body with the brightest M42 camera viewfinder, a good top shutter speed, and third generation metering technology, go with the Bessaflex. Otherwise, the fifth generation systems are great but limit full functionality to a smaller world of proprietary lenses. There is no right answer, but there are probably plenty of wrong ones.

Aftermarket Options

Given the fact that no truly great M42 body was ever produced,, many folks decide to skip them altogether and adapt the lenses to more modern and capable cameras. While M42 lenses can easily be adapted to any modern mirrorless digital system, they cannot be fully adapted with full infinity focus to many film SLR mounts. The popular mounts that can be used with full infinity focusing include: (1) Konica Autoreflex; (2) Praktica PB; (3) Pentax K; (4) Canon EF and FD; and (5) Contax C/Y. None of these cameras permit “true” aperture-priority autoexposure with M42 lenses as they cannot couple to the lenses’ aperture pin. However, aperture-priority operation is still possible, the camera will just not know what aperture the lens is set at and the viewfinder will darken as the lens is stopped down. For those looking for a non-native film camera body to use M42 lenses, there are many alternatives.

Konica Autoreflex: Konica produced an OEM adapter for M42 lenses, labeled “for Praktica.” However, there are several reasons why Konica AR bodies are not ideal platforms. First, most Konica bodies do not have the brightest viewfinders. Second, the Konica’s shutter-speed priority operation makes metering M42 lenses are bit more difficult. To take a metered shot on an AR body, you first have to focus with the aperture set wide open on the lens. Then, you must stop the lens down and set the appropriate shutter speed to have the Konica body’s metering needle or LED to reach a certain blank spot in the viewfinder above the largest aperture. This operation is necessary because Konica bodies show the aperture in the viewfinder and not the shutter speed. Third, Konica bodies are all limited to a 1/1000 top speed and center-weighted metering. While M42 lenses will work on Konica AR bodies, it is not an ideal second marriage.

Praktica PB: When Praktica switched over from M42 to its bayonet “PB Mount” in 1979, an OEM adapter was initially offered that offered a kind of stop-down aperture-priority metering operation. The higher-end models of Praktica’s PB cameras (like the B200, BC1, and BX20) are actually pretty nice, with brighter focusing screens and better focusing aids than most any other classic 1970s M42 body. The catch is that there is only one available adapter which is fairly rare but not really expensive. The OEM adapter has the correct electrical contact as a Praktica PB camera will not meter a lens that cannot make that contact with the body.

Pentax K: There are few lens mounts as iconic as the Pentax K. Like the Praktica B, an OEM adapter from M42 to K mount was offered to attract the legacy users of the older system. However, no communication between the body and the lens existed, requiring aperture priority, stop-down operation. With so many K-mount cameras produced under so many brands in multiple countries, let’s just pick up the LX as an example. The LX has a top shutter speed of 1/2000, a center-weighted meter, and a bright viewfinder, basically Pentax’s equivalent of the Nikon F3. However, there really is no reason to use Japanese M42 lenses on a Pentax K mount camera because Pentax K-mount lenses are generally regarded as superior to its M42 lenses. At the same time, a camera like the Pentax LX may be a good platform for East German and Soviet lenses, as many of these are sufficiently distinguishable from Pentax lenses to produce different results.

Canon FD/EF: As someone who normally does not use Canon SLR products, I have no firsthand experiences to share. However, there is literally almost 20 years now of internet discussions now about using M42 lenses on Canon digital SLRs. There are certainly some super advanced Canon film SLRs in EF mount that will be able to use M42 lenses at fast shutter speeds, with great viewfinders, motor drives, etc. A quick internet search will reveal dozens of sites and thousands of internet forum postings with useful information if you are looking to go the Canon route.

Contax C/Y: With bright viewfinders, multiple metering modes, top shutter speeds of 1/4000 (up to 1/8000 on the RTS III), relatively quiet shutters, and integrated motor drives, Contax may make the best case (along with Canon) for a non-native M42 lens platform. Various third-party companies make reasonably-priced generic adapters that seem to all operate in the same manner (and all have a little focus slop). Using M42 lenses on Contax bodies is a delight and certainly a good alternative.