Bayonet

Sears SL11 from 1964 – a relabeled Ricoh SLR with a Nikon F mount.


Few cameras have more obscure and incestuous origins than this one.


At the beginning of the Sixties, Mamiya was ready to launch its first 35mm SLR, the Prismat, and following a suggestion of its US importer, agreed to develop and manufacture a version of the camera for Nippon Kogaku, the maker of the already famous Nikon F. The Nikkorex F was launched in 1962, at half the price of the model F. Nikon expected that the new camera would penetrate the amateur phographer market and increase the sales potential of the Nikkor lenses. Nikon learned quite a few things in the process, and put that experience to good use when they launched the Nikomat in June 1965.


In 1964, Ricoh presented the Singlex, which was very similar to the Nikkorex F, F mount included. It is unclear whether Ricoh was just relabeling cameras made by Mamiya, or whether they had bought the plans and the tooling after Nikon and Mamiya had lost interest in their joint venture. In any case, Ricoh was one of the main manufacturers supplying Sears-Roebuck with private label cameras, and the Singlex was rapidly incorporated to the Sears catalog under the Sears SL11 moniker.

The Sears SL11 with the standard Rikenon 55mm lens
The Sears SL11 with the standard Rikenon 55mm lens


Technically, it can be argued that the Ricoh and Sears cameras were not using the real “F” mount, but only a very close variant: Nikon’s bayonet mount is using lugs to help position the lens on the body (3 body-side lugs imbricated with 3 lens-side lugs). On the Ricoh and Sears bodies, one of the lugs was shorter than Nikon’s , leaving room for a larger lug on the lens side. As a consequence, a Nikon lens with its “small lug” could be mounted on the Ricoh and Sears camera bodies, but the “big lug” Rikenon lenses shipped with the cameras could not be mounted on a Nikon body.


In 1967, Ricoh and Sears replaced the Singlex and the SL11 with new models designed and built by Ricoh. They did not use the Nikon F mount, but the ubiquitous 42mm screw mount, and were equipped with a TTL CdS exposure meter. It seems that Ricoh and Sears designated the new models with the same Singlex and SL11 names as the models they were replacing, at least for a while. The cameras were also sold as Ricoh Singlex TLS and Sears SLS or TLS in the subsequent years. As we can see, using confusing product references is not a recent practice.

How to spot a Sears SL11?

The Sears label on the pentaprism housing. The Sears retained the accessory holder of the Nikkorex.
The Sears label is glued on the pentaprism housing. The Sears SL11 retained the vertical accessory holder of the Nikkorex, at the left of the mount.
The Copal metal shutter
The Copal metal shutter. Mamiya was the first camera manufacturer to use a vertical Copal shutter. Nikon and Ricoh kept it in the Nikkorex and the Singlex.
Made by Ricoh
On the back of the body, the name of Ricoh is engraved. There are some traces of glue. A Sears label may have covered Ricoh’s name originally.

Using the Sears SL11


The big difference between film and digital photography is that the body of a film camera does not play such an important role as the body of a digital camera in the final quality of the picture. If the photographer is technically competent and has enough time to set up the camera, any Single Lens Reflex with no light leak and an accurate shutter will give good results, provided a good film and a good lens can be used.

Marietta-the wall of the train station
Marietta, GA- The wall of old the train station. The shutter release of the SL11 is very sensitive, and this picture was taken accidentally. The camera took the decision for me and I tend to like the result.


With a recent Nikon fast prime lens and fine grain film, the SL11 will not be as convenient to use as a modern film SLR (no exposure metering, no autofocus), but if the subject is static or cooperative, there will be little difference as far as the pictures are concerned.


The SL11 is a fairly large and heavy camera – it’s larger than the Nikon F and with its standard 55mm lens, it tips the scale at more than 1.2 kilos. I’ve also held a Nikkorex F in hands, and both cameras share the same matte aluminum finish, which seems very difficult to keep clean in the long run (dust and grease seem like ingrained in the camera’s outer shell). The body shell of the Sears model is not exactly similar to the Nikon’s, but the SL11 is absolutely identical to the Ricoh Singlex, with the exception of a Sears label pasted on the prism cover; Ricoh’s name is engraved on the back of the camera, so that there s no doubt on its origin.


As can be expected from a camera designed in 1962, no exposure meter has been incorporated, and the photographer will have to rely on his experience, on a hand exposure meter or on the Sunny 16 rule to determine the right aperture/shutter speed combination. The camera and the lens support Nikon’s automatic aperture pre-selection, and the diaphragm stays at full aperture until the shutter release is pressed. As a consequence, and surprisingly for a camera that old, the viewfinder is very bright.


In the field, the camera surprises with a very sensitive shutter release, and the very high demultiplication of the focusing ring of the lens seriously slows down the operations. As expected, the shutter is rather loud. The lens is still very good. There is some flare in back-lit situations, but at mid aperture (f:8 or f:11), it produces razor sharp pictures.


A camera without a built-in exposure meter is too slow to use to my taste, but this one is an interesting curiosity. Compatible with any Nikon lens made in the last 50 years, provided it has an aperture ring, it will find a place in the equipment bag of a “Nikonist” between a FE2 and a D300, for a film roll of nostalgia.


More about the SL11 and its cousins

The Sears SL11 with a Nikon 24mm AF lens. It simply works.
The Sears SL11 with a Nikon 24mm AF lens. The SL11 is compatible with any Nikon lens provided it has an aperture ring.


The common ancestor: the Mamiya Prismat NP.
Ron Herron’s site is totally dedicated to Mamiya 35mm cameras.


The predecessor of the SL11: the Nikkorex F and Nikon’s own version of its history, reported by Kenji Toyoda.
Kenji Toyoda went to the source and talked to the Nikon engineers who worked on the development of models such as the FM, the FE or the FA. For Nikon, they’re “the best of the rest”.


Nikon’s official Web site offers a very detailed history of the most important cameras of the company: More about the history of the Nikon cameras – the legendary and the other ones : Nikon Imaging Products


A few sites have a pages dedicated to the twins of the SL11:
– the Ricoh Singlex (first model).
– another source of information for the Singlex and the Nikkorex F : Richard de Stoutz and his Nikon F collection.


As explained above, Ricoh and Sears kept on using the Singlex and SL11 names after they abandoned the original design of Mamiya. The user manual of Ricoh Singlex TLS of 1967 is still available.
The Sears labeled version of the camera is also shown here as the Sears SLS.

Marietta, GA - Jan. 2010
Marietta, GA – Jan. 2010 – Sears SL11 with Rikenon lens (55mm f:1.4)-Lodak CN400

50 Years of Lens Mount Evolution: Part VI of VI


The last 10 years – digital cameras and image stabilized lenses


The massive adoption of digital cameras has not led – so far – to a dramatic change of the design of the lens mount of the cameras. Canon, Nikon, Pentax and Sony (aka Konica Minolta) did not design specific lens mounts for digital cameras, even if they designed specific series of lenses adapted to the smaller size of the digital “APS-C” sensors.


Panasonic GF1 and G1
Panasonic GF1 and G1 - the most radical development in interchangeable lens cameras since the Contax S and the Leica M3 (Photo courtesy of DPReview)


Only camera makers which had been absent from the 35mm Autofocus SLR market and had no installed base to please had the liberty to start from a clean slate. In 2003, Panasonic and Olympus launched the “Four Thirds” format, combining a relative small size sensor with a large all-electric mount. Last year, Panasonic finally presented the Micro Four Thirds G1, a camera with an electronic viewfinder and interchangeable lenses (EVIL), the first digital camera to really depart from the conventional SLR design of the Contax S of the late forties.


Why did the camera manufacturers keep the same bayonet mount for digital?


When the first digital SLRs from Nikon and Canon were presented in 2000, large imaging sensors were so difficult to manufacture and therefore so expensive that the camera makers settled for a form factor smaller than the 36x24mm dimensions of 35mm film (23.7mmx15.6mm for Nikon, 22mmx14.9mm for the Canon EOS-D30).


This form factor was dubbed “APS-C“, because it was close to the dimensions of an APS picture, shot with the “Classic” image format (25.1×16.7mm) of the APS cameras. The sensor being smaller than a 35mm negative (the diagonal of 35mm film is 1.5 times larger than the diagonal of an APS-C imager), the camera makers had an opportunity to design a new series of smaller bodies and lenses, but they all decided to stick to their legacy lens mounts and to design digital SLRs at least as large as their film counterparts.


Being the undisputed leaders of the film camera market, Nikon and Canon in particular had no interest in starting a new incompatible product line, at the risk of alienating their large user base; it would have leveled the playing field, and offered an easier entry in the dSLR market to companies like Panasonic or Sony. Nikon and Canon also wanted to limit the cost and the technical risk of going digital by reusing most of the components of their film cameras in their first generations of dSLRs. And they may have anticipated that one day, with the help of Moore’s law, cameras using full size digital sensors would become affordable for their professional and enthusiast customers, making their large F or EF bayonets more relevant than ever.


For a few years, however, dSLRs with APS-C sensors were the only game in town. Canon and Nikon both developed specific lenses for their small sensor bodies. Canon decided to modify the EF mount so that the EF-S lenses designed for the small sensor cameras can not be mounted on full frame SLRs or dSLRs. Nikon did not change the F bayonet – small sensor DX lenses can also be mounted on full frame (or FX) bodies, but being designed for the APS-C sensor size, they do not cover the full format of the FX sensors and the image is automatically cropped.


The Four Thirds and Micro Four Thirds formats


In 2003, Olympus and Panasonic launched the “Four Thirds” format. At that time, Canon had already started producing the first full frame 35mm digital camera (the EOS 1D), and was preparing much more affordable 35mm digital SLRs like the EOS-5D for the enthusiast photographer market. A large sensor was still complex and expensive to manufacture, but getting high quality pictures out of it would prove much easier than with a small sensor, in particular in low light situations.


The Olympus Four Thirds system was based on design decisions completely opposed to Canon or Nikon’s . The sensor size chosen for Four Thirds cameras is very small (its diagonal is only half of the diagonal of a 35mm sensor), but at the same time the lenses and bodies are designed around a large diameter bayonet mount (44mm, the same as Nikon’s F), with a relatively long focal flange distance (38mm). When the system was designed, it was believed that a large diameter lens and a long focal flange distance were required to get optimal results from the imaging sensor, but the Leica M8 and M9 have since proven that it was not the case.


On the positive side, the relatively large dimensions imposed by the Four Thirds mount gave the engineers more freedom to design high quality lenses with very fast apertures, but on the negative side the body & lens combination could not be made significantly smaller than the more conventional APS-C cameras of their competitors. To add insult to injury, the relative small size of the sensor proved a handicap in low light situations (all things being equal, small sensors are more subject to noise than larger ones), and steered most of the enthusiast photographers away from Four Thirds cameras. Four Thirds only got traction on the low end of the market.


Size comparison: Nikon 18-55 DX, Olympus 14-42, Panasonic 14-45 Micro 4/3
Size comparison: Nikon 18-55 DX (APS-C), Olympus 14-42 (Four Thirds), Panasonic 14-45 (Micro Four Thirds) - Image courtesy of DP Review


Failing to make a significant impact on the mid-level dSLR market, and completely barred from the professional market dominated by new full frame cameras with extraordinary low light capabilities, Panasonic and Olympus decided to create a new niche for themselves, and launched Micro Four Thirds cameras. Using the same sensor as the “Four Thirds” dSLRs, the Micro 4/3rd cameras have abandoned the reflex mirror chamber and the pentaprism viewfinder of conventional dSLRs for an electronic viewfinder. They are designed for a much shorter focal flange distance (approx. 20mm instead of 38mm, and the mount diameter is also smaller (32mm approx. instead of 44mm).
As a result, the body+lens combination is much more compact than any other dSLR on the market. It’s still difficult to predict how this new category of cameras will fare in the future, but they finally bring something new to the table.


Image Stabilization

The migration from film to digital is without a doubt the most significant evolution of photographic equipment in the last ten years. Image stabilization gained acceptance during the same time, and is now a feature expected by amateurs using digicam as well as enthusiasts and pros using expensive large aperture teles. The objective of image stabilization systems is to compensate automatically the involuntary movements of the photographers, and to produce sharper pictures even at slower shutter speeds.


Canon, Nikon and Panasonic adopted relatively similar systems, all based on the controlled movement of optical modules installed inside the lenses. Minolta, Pentax and Olympus opted for in-camera systems compensating the movements of the photographer by moving the image sensor itself. Apparently both systems produce good results. In-camera image stabilization systems do not require any change to the lens mount, but in-lens systems need to be managed from the body, and require a few more electric contacts. Most of the current lens mounts are all-electric now, and adding a few contacts is an easy done job.


The state of the art in 2009


Pentax: Progressive introduction of the KAF3 version of the K bayonet mount, with autofocus motor in the lens. The majority of the lenses in the product line still need an autofocus motor in the camera body.


Canon: No change to the EF mount of the EOS cameras. Starting with the Rebel and the 20D cameras, Canon used a specific variant (EF-S) of the mount for lenses dedicated to the APS-C format. Canon dSLRs all work with EF lenses, but only the Rebel and 20D, 30D, 40D and 50D cameras can use the EF-S lenses.


Minolta, Konica Minolta and Sony: Progressive introduction of SSM lenses, with the focusing motor inside the lens. The majority of the lenses in the product line still need an autofocus motor in the camera body.


Nikon: Multiple variants of the F mount were used during the last 15 years:
– AF-D: no mechanical difference with the AF mount, the D lenses transmit the focusing distance value back to the body for 3D Matrix Metering
– AF-I: focusing motor in the lens – used for tele-lenses between 1992 and 1996;
– AF-S lenses: ultra-sonic (“Silent Wave”) autofocus motor built into the lens. Most of Nikon’s zoom lenses are now AF-S, and the conversion of prime lenses has started a few years ago.
– The new PC-E (perspective control electromagnetic) lenses now use an electromagnetic diaphragm command. All the other Nikon lenses still use the mechanical stop down mechanism introduced with the F mount in 1959.


Olympus & Panasonic started promoting the Four Thirds format in 2003. Four Third lenses use an all electric bayonet mount. The Micro Four Thirds are more compact, and use 11 electrical contacts instead of 9 for regular Four Third lenses. Thanks to the very short focal flange distance of Micro Four Third cameras, it is easy to develop adapters for Canon EF, Nikon F, Olympus OM or Leica M or R lenses.

Gull in Essaouira (Morroco)
An exception on this blog: a digital picture (Nikon D80) taken in Essaouira - Morroco

50 years of lens mount evolution (Part I of VI)


Nikon was very proud a few months ago when the 50th anniversary of the F mount was celebrated. Half a century! Pentax had to abandon its original mount and transition to a new bayonet in the early seventies, Minolta and Canon in the mid eighties.

Nikon F - Photo courtesy of cameraquest (www.cameraquest.com)
Nikon F – Photo courtesy of cameraquest (www.cameraquest.com)


But there is more to lens and body compatibility than the design of the bayonet.


Even if the current Nikon bodies and lenses still use the same bayonet design as the Nikon F of 1959, it’s practically impossible to pair an unmodified lens from 1959 to a recent body, and vice versa: the lens and the body of a modern SLR have to exchange information and commands, and non-upgraded lenses from 1959 simply don’t share enough information to be usable.


The transmission of information from the lens to the body – focal length, maximum and minimum aperture, pre-selected aperture, focusing distance, and of commands from the body to the lens – setting the focusing distance, setting the aperture value, closing the diaphragm, can be performed from many different ways – some of them passive (a hole in the metal), some of them mechanical (rods, cogs and springs), the most recent working exclusively through electrical contacts.


Diaphragm pre-selection


Cameras of the mid fifties were far less complex than the ones we now use. No internal meter, no auto exposure, no auto-focus.


But users of SLR cameras were facing an important issue: because the viewfinders of their cameras were dim and the focusing screen grainy, the only practical way to set the focus was to open the aperture to its maximum. Let’s say F:1.4. But if on a sunny day they needed to shoot at 1/125 sec at F:11, they had to set the aperture ring to F11 AFTER they were finished with the focus and – of course – BEFORE they took the picture. Not very fast, not very convenient.


At the end of the fifties, most Japanese camera manufacturers adopted automatic diaphragms with aperture pre-selection: the lens remained at full aperture – let’s say F:1.4 -independently from the aperture value selected by the user on the aperture ring, making focusing easy. Only when the user pressed the shutter release to take the picture would a lever or a rod mechanically close the diaphragm to the value pre-selected by the user.

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