This page does not attempt to be a complete history of photography, from the daguerrotype to the digital ctramera of today. Instead, it looks at a few types of camera in order to explore one particular line of development within the history of film cameras.
To start off, the image at right is of an Ermanox camera. This was made by Zeiss, and it used glass plates. One could get an f/1.8 Ernostar lens for it, which was an incredibly wide aperture for the time.
This was the camera that Erich Salomon used for his famous work in available-light photography.
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The Leica, pictured at right, originated the 36mm by 24mm image format for 35mm film. It was used for candid photography by a number of famous photographers, and thus, it seems to me, it could be viewed as the spiritual successor to the Ermanox. Two images are shown at right; the top one is of the Leica as it was when originally introduced in 1925; the second is of a later version, the Leica IIIg, dating from 1957.
Henri Cartier-Bresson was a famous photographer who was an early user of the Leica.
The image at right shows another rangefinder camera using 35mm film. However, it is no mere imitation of the Leica, as this camera by Edixa has a very obvious special feature: two lenses, separated by approximately the same distance as the human eyes, in order to take stereo pictures for a three-dimensional effect.
One of the most popular cameras of this type was the Stereo Realist camera; Kodak made one that was compatible with it, and a stereo camera using 16mm film was sold as the View-Master Personal Stereo Camera. Many other companies made stereo cameras for a time; and, of course, such cameras are not new, as the Stereopticon for viewing three-dimensional stereo images dates back to the nineteenth century.
Another line of development involves improving the camera by allowing the photographer to see exactly what the photograph will look like through use of the reflex principle.
Pictured at right is a Rolleiflex camera, a notable example of a twin-lens reflex camera. For a time, nearly every camera company made a camera of this basic type.
Of the two lenses in the front of the camera, the bottom one was the one that exposed the film; the top one, often of a simpler construction with fewer elements, was used to form the image on a ground-glass plate used in the camera's viewfinder. A mirror at a 45 degree angle allowed that plate to be in the top of the camera. This is illustrated in the diagram of the basic elements of a twin-lens reflex camera at the left.
Note that there is a round lens opening at the top of the camera to look through at that image in this photo; often, the shade around the ground glass is simply open at the top instead, but a magnifying lens may be available as an option.
Since that image is formed through a different lens, above the one that exposes the film, of course the preview in the viewfinder is not exactly the same as the finished photograph (in addition to being mirror-reversed, although it is right-side up).
Kodak's Brownie Hawkeye camera, shown at left, which was very popular because it sold at a low price, was a viewfinder camera, not a twin-lens reflex, despite the fact that it used waist-level focusing. Because of that, the viewfinder image was bright enough that no shade was needed.
This camera used Kodak 620 film. The film was basically identical to Kodak 120 film, but it was wound on a smaller spool so as to allow cameras using it to be more compact.
On the other hand, the Bolsey C camera, seen at right, was a twin-lens reflex camera. But not only did it have a compact and slim form which caused it to resemble a rangefinder camera, it also in fact included a rangefinder, just like the Praktina FX which we will see below, which was an SLR that also had a rangefinder.
The minor imperfection of a mirror-reflected image, of course, can be corrected by going to the famous Single-Lens Reflex type of camera.
Such cameras have been around for a long time; Wikipedia notes that the principle was patented in 1861, and by 1885 the Monocular Duplex was being sold commercially.
Pictured at left is a single-lens reflex camera from 1910, Watson's "Argus" Reflex. It even has a focal-plane shutter.
And pictured at right is a single-lens reflex camera from 1936 by Graflex, the National Graflex Series II.
The diagram shows how it works; the lens (5) is a relatively simple one, and so it has no back focus issues, and there's even a bellows (4) to extend it out.
A mirror at a 45-degree angle (3) reflects the light to the ground-glass plate (2) on which the image is viewed; it flips up out of the way when a photograph is actually being taken in order to let the light reach the film behind it.
And there is a shade (1) around the ground glass to allow the photographer to see the image when looking down at the camera.
This camera used standard 120 roll film, and was reasonably compact and easy to carry. Note, however, that because it doesn't have a pentaprism, it still does have a viewfinder image that is mirror-reflected.
A larger SLR from Graflex, the Home Portrait Graflex, required a 5 inch by 7 inch plate or film area; it offered tilt and rotate movements with its bellows for control of perspective.
Graflex is also the company that made the Speed Graphic camera, which was widely used by newspaper reporters.
Watson's "Argus" Reflex was a British camera; 1936 happened to be the year where a camera company was founded in the United States that took the name Argus. The reason this is a good name for cameras is that Argus was a giant in Greek mythology who had many eyes, and thus could see in all directions. Initially, he just needed four eyes for that, but later on they settled on a hundred eyes.
The Kine Exacta, originally sold in 1935, and which continued to be made in East Germany after the war, is an early single-lens reflex camera which used 35mm film. To take a picture, one looked down at the ground glass plate, which was surrounded by a shader, as with the Graflex above.
In 1949, the East German portion of Zeiss, Carl Zeiss Jena, offered the Contax S camera to the world.
This was not the first 35mm SLR to feature a pentaprism, the Rectaflex, shown at left, from Italy having preceded it by a year. But the Rectaflex was not nearly as successful.
The Contax S also introduced the M42 screw mount, which became the standard mount for 35mm SLRs until more elaborate arrangements for connecting the lens to the camera were required for such features as automatic exposure with shutter priority, in which the camera needs to have control over the f-stop setting in the lens, and, much later, autofocus as well.
Another very early 35mm SLR with a pentaprism was the Alpa Prisma-Reflex from Switzerland, shown at left.
The Exakta Varex, sold as the Exakta V in the United States, shown at left, was another very early camera to offer a pentaprism. In this camera, the pentaprism could be removed, both to allow the focusing screen to be changed and to allow switching to waist-level viewing.
This was also true of later cameras from Exakta, such as the Exakta Varex VX (or the Exakta VX in the United States) shown at left, which came out the following year. This allowed a number of special accessories to be used with the camera, and thus there were advertisements for Exakta cameras noting their applicability to taking photographs through a microscope for scientific purposes, an example of which is shown at right.
Before these models were introduced, a pentaprism attachment that sat on top of the shader hood for an older Exakta was offered for sale, as pictured at right. This is also how a pentaprism option was provided for the Praktica fx camera.
Below is a diagram showing the basic parts of an SLR:
Nearly all 35mm SLR cameras have interchangeable lenses, allowing for the use of wide angle, telephoto, and zoom lenses in addition to the basic standard lens (usually with a 50mm focal length). This makes a major contribution to the versatility of this type of camera.
Usually, because its size depends strongly on the lens design, the iris diaphragm is located within each lens; turning a ring on the lens sets the desired aperture, but the lens is not actually stopped down to that except when the photograph is actually taken. The mechanical coupling that accomplishes this is the only coupling between the lens and the camera body in an SLR using the M42 screw mount.
However, some cameras were different; the Kodak Retina camera had a leaf shutter positioned between the lens and the camera body instead of the usual focal plane shutter. The leaf shutter was, of course, far more common on other types of camera, even if not on SLRs.
The reflex mirror, at an angle of 45 degrees, sends light from the lens up to the ground glass on which the photographer views it, seeing what the photograph to be taken will contain.
This mirror swings up, out of the way, when the focal-plane shutter is about to open and expose the film to take a photograph.
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The image above is from Wikimedia Commons, licensed under the Creative Commons Attribution Share-Alike 3.0 Unported License, and is thus available for your use under the same terms. Its author is Hiyotada. |
Canon, in 1965, made a camera, the Canon Pellix, pictured at left, that avoided this motion and noise by instead using a pellicle for the reflex mirror which remained fixed in place, reflecting about a third of the light to the viewfinder, and admitting the other two-thirds to the film. Much later, in 1989, they used this principle again in a short run of the EOS RT model of camera, and a couple of other manufacturers have also tried this principle at least once.
Above the ground glass is a field lens, which helps to ensure the light from the camera's lens goes to the eye of the photographer.
The pentaprism is shown here with the surfaces that are used to reflect the image on the ground glass plate as being silvered. In the front of the pentaprism is a simple flat surface that will reverse the image once; on the top is a mirror divided into two parts that meet at a right angle in the middle; this kind of mirror does not reverse the image, and so ensures that the pentaprism correctly modifies the image on the ground glass so as to match the orientation of the scene in front of the camera.
A three-dimensional diagram, like this one, taken from a manual for the Praktica fx-2 camera, may be easier to understand than the flat two-dimensional diagram shown above.
Note that a line, composed of dashes and dots, shows the central axis of the path of light from the object being photographed into the camera, and through the viewfinder.
Note that in front of the pentaprism, there is a convex lens appearing to lean against it. What is this extraneous item?
It is there because the Praktica fx-2 is another example of a camera in which the pentaprism is removable. When the pentaprism is not in use, this extra lens may be swung up in order to magnify the central part of the image on the ground glass for finer focusing, as shown in the illustration below, also taken from that camera's manual:
Here is an even clearer three-dimensional diagram, adapted from one that appeared in the manual for the Praktica VLC camera. (I changed it by omitting the camera's automatic exposure system from the diagram, and by highlighting the eyepiece lenses in blue to indicate they also refract the light on its way to the photographer's eye.)
There are possible replacements for the pentaprism in an SLR viewfinder.
On the left of the diagram above, a pentaprism is shown.
In the middle is shown how one could achieve maximum lightness by eliminating the heavy glass pentaprism, and instead placing mirrors where its reflecting surfaces are. (The fact that distances are affected by the index of refraction of the bulk glass between surfaces is neglected in this diagram.) This is sometimes done for large format cameras, where the pentaprism would be larger and heavier.
On the right is shown an in-between possibility. Here, a much smaller prism is retained for one part of the pentaprism, the two reflecting surfaces at right angles on the roof of the prism, but the other reflecting surface is now provided by a mirror. The prism at the top is known as a Porro prism, giving this type of viewfinder its name.
These three types of viewfinder, as shown, should be nearly equivalent in terms of the size and brightness of the image in the viewfinder; however, I have read that the few cameras which had Porro viewfinders as an option provided smaller and dimmer images in the viewfinder if this type of viewfinder was used; therefore, I must conclude that typical Porro viewfinders actually used, unlike the one in my illustrative diagram above, also made other design changes compared to the pentaprism for the same camera.
It did not take long for a very large number of camera companies to bring out their own 35mm SLR cameras, as the pentaprism, allowing the image to be previewed conveniently by looking forward just as with an ordinary camera viefinder, made this type of camera much more convenient to use.
Pictured at right is the Contaflex, from the West German piece of Zeiss, Zeiss Ikon.
Apparently even before the Contaflex, Zeiss Ikon was selling SLRs with pentaprisms, under the Contax-S name, as I have seen advertisements for them in old photography magazines. In the meantime, as the East German firm lost the rights to certain classic camera names in the West, the Contax-D was sold as the Pentacon in the West, and so on. Zeiss Ikon, instead of making their own Contax-S, was acting as the importer for the original Contax-S made by Carl Zeiss Jena in East Germany; although the camera bears Zeiss Ikon branding, the advertisement for it shown at left explicitly credits the East German firm of Carl Zeiss Jena for its design and construction, giving a planetarium projector of theirs as an illustration of that firm's abilities.
In 1956, the same year that the Praktica fx-2 came out, the same East German firm that made it also brought out the Praktina FX. This was their top-of-the-line camera; like the fx-2, its pentaprism was removable. But instead of using a screw mount for its lenses, it introduced a bayonet mount, as many other camera makers would eventually do. But its most unique feature is that although it was an SLR, it also had a rangefinder built into the camera body, similar to those found in rangefinder cameras. This allowed it to be used as if it was a rangefinder camera, thus making it effectively two cameras in one, except, of course, for not being as light as a rangefinder camera.
Even Eastman Kodak offered an SLR, the Retina Reflex, starting in 1957. The most distinctive feature of Kodak's Retina Reflex cameras is that they had a conventional shutter, located on the body immediately behind the lens, rather than the focal plane shutter usually found on single-lens reflex cameras.
While this seems to be a highly unusual design decision, it was not a unique one. In fact, this was also true of most of the Contaflex line of cameras, the first of which was just mentioned above.
Focal-plane shutters achieve high effective shutter speeds by allowing only a small part of the film to be exposed at any one time as the shutter moves across the film area. This leads to two major drawbacks. One is that the shutter is limited to flash synchronization speeds slow enough to allow the entire exposure area of the film to be open to incoming light at the same time; this could be as fast as 1/125 second with a fast metal vertical focal plane shutter. The other is that at fast shutter speeds, fast-moving objects will have their shapes distorted.
A leaf shutter in the lens, on the other hand, can synchronize with flash at any speed at which it can operate, and does not create artifacts of shape distortion because the whole film is exposed, or not, all at once.
Thus, while focal-plane shutters were far more common in SLRs, there is still a list of several SLRs with the other type of shutter instead: The Contaflex, the Voigtländer Bessamatic and Ultramatic, the Alps Ambiflex, some early Topcon cameras, and the Kowa SER, SETR, and SETR2.
The Achilles heel of this type of camera, however, has tended to be that the variety of lenses available for any particular camera of this type has tended to be limited. One contributing factor is that sometimes some optical elements of the lens are behind the shutter on the camera body, making only the front part of the lens interchangeable, in order to more closely approximate the ideal position of the shutter within the lens. However, some of the manufacturers of this kind of camera made an effort to avoid this pitfall.
Also, other camera makers that chose to use focal-plane shutters still sought to make the benefits of leaf shutters available to their customers by making available for their cameras a limited number of lenses with built-in leaf shutters that could be used while the focal-plane shutter was left open, as for a time exposure.
 Image by FlanellKamerasFilm from Pixabay |
A later example of how the 35mm SLR swept all before it is the camera shown at right from 1976. Yes, even the firm of Ernst Leitz Wetzlar, known for the storied Leica rangefinder camera, found the need to enter the SLR market.
The camera bodies were made in Portugal; note that the lens proudly proclaims that it is made in Canada!
Actually, Leica was in the SLR business well before 1976; here is their Leicaflex SL from 1969.
The first 35mm SLR produced by the Japanese firm of Asahi Optical, the Asahiflex, shown at right, did not have a pentaprism. But in a later model, they remedied that lack; that model was called the Pentax, and that was also what they eventually changed the name of their company to.
The Asahiflex was the first Japanese 35mm SLR, arriving in 1952.
The Pentax wasn't the first Japanese SLR with a pentaprism; the Miranda T, shown at left in an image graciously placed in the public domain by Jan von Erpecom on Wikimedia Commons (which I have subsequently cropped somewhat), was the first, coming out in 1955. The Pentax arrived in 1957.
But it was 1959 that was a banner year for the Japanese camera industry; in that year, three Japanese companies debuted 35mm SLR cameras; Canon came out with the Canonflex, Yashica came out with their Pentamatic... and Nikon, in April of that year, introduced the legendary Nikon F camera, pictured at right, which soon became the preferred choice of professional photojournalists.
Pictured at left is a Nikon S-2 rangefinder camera. This camera preceded the Nikon F, and it was advertised as "the Fastest Handling '35' in the field", certainly an attribute of value to news photographers. Its predecessor, the earlier Nikon S, was widely used by news photographers covering the Korean War, and their familiarity with this Nikon product is likely to have contributed to the merits of the Nikon F camera being quickly recognized.
Shown at right is the Nikon F2, the successor to the Nikon F, and
shown at right is the Nikon F3, the successor to the Nikon F2. The Nikon F, the Nikon F2, and the Nikon F3 all have removable viewfinders. This allowed Nikon F and Nikon F2 cameras to be upgraded to include automatic exposure control, and it also allowed the ground glass screen to be exchanged for ones having different designs in which the features for assisting in focusing the camera were different.
This characteristic was shared with the Exacta cameras for which pentaprisms were available, and with the Praktica fx-2, and fx-3, and the later Praktica VLC, VLC 2, and VLC 3 as well as the Praktina fx and the Praktina IIa, some of which we met earlier.
But Nikon wasn't the only later camera maker to offer this feature in their most versatile cameras. Interchangeable viefinders were also a characteristic of the Canon F-1 (and also the later New Canon F-1), the Minolta XK (or the Minolta XM outside the United States), and the Pentax LX. Also, many Miranda SLR cameras had removable viewfinders. And so did the Alps Ambiflex, which also used a leaf shutter instead of a focal plane shutter.
Pictured below are the Praktica VLC, the Pentax LX, the New Canon F-1, and the Minolta XK from among the cameras having this elite feature.
The name Nikon is derived from Nippon Kogaku, which literally means "Japan Kodak". This is not even unique; JVC, the company that came up with the VHS videotape format, is the "Japan Victor Company". Apparently, there was a time when major U.S. trademarks were not safe in Japan.
And yet, Nikon and Kodak, although both leaders in the field of photography, seem, if anything, to be opposites. Kodak is primarily focused on products for the consumer, at least in the area of cameras, (as a major film supplier, they did very much consider the needs of professionals in that part of their business) while Nikon emphasized high-end professional gear.
One example of how Kodak focused on making photography easier for the consumer was their introduction of certain new film formats.
In 1963, they introduced Instamatic cameras, which used 126 film in special cartridges, which eliminated the need to thread film and the risk of accidentally exposing it.
The film in an Instamatic cartridge was 35mm wide, but it had a backing sheet of paper with exposure numbers printed on it, as with 620 roll film or 127 roll film - and, as well, it did not have perforations on its sides either. Thus, it was basically the same kind of film as previously sold by Kodak as 828 roll film. Pictured at left is the Kodak Pony 828 camera from 1949, an example of a camera that used this film format.
While most of the Instamatic cameras made by Kodak were simple point and shoot cameras, with fixed-focus lenses, Kodak did get around to making an SLR camera that used these 126 film cartridges, as depicted at right, and, in fact, there were also such cameras made by Ricoh, Rollei, Zeiss Ikon (under their Contaflex brand), and the Keystone K 1020 (which is, according to one web site, suspiciously similar to the Mamiya Auto-Lux 35mm SLR). The Kodak Instamatic Reflex used the same type of lenses as the previous Kodak Retina Reflex SLR, and thus did not opt for a focal-plane shutter. (This is not as strange as it sounds. The Kodak Instamatic Reflex camera was introduced in 1968; the Kodak Retina Reflex IV camera was sold from 1965 to 1967, so those cameras were not a long-forgotten relic of the past at the time. But there is still something strange here: if the Instamatic Reflex camera was worth making, why was the Retina Reflex discontinued: it wasn't as if 35mm film was going anywhere?) However, the conventional shutter it did have was one of the first electronic shutters to be used in a consumer camera.
The standard image size for 828 film was 40mm by 28mm, and there were only eight exposures on a roll. Since Kodak had continued to make and sell 828 film until 1985, one is tempted to ask, in order to avoid wasting film on sprocket holes, why the world's compact SLR cameras weren't made to use 828 film instead of 35mm movie film, even if the precedent of using 35mm movie film was set by the Kine Exakta?
Well, there's actually one obvious reason why not, but if Kodak could make both 120 film and 620 film, obviously it could have sold the same kind of film as used in both 828 reels and Instamatic cartridges on reels that held 25 exposures instead of just eight.
Of course, SLR cameras using 828-style film, particularly assuming they still used the standard 828 frame size of 40mm by 28mm, would have been slightly larger: a 36mm by 24mm frame has a diagonal of about 43.266615mm, while a 40mm by 28mm frame would have a diagonal of about 48.826222mm, so a normal lens would presumably have a focal length of 56mm in that world. On the other hand, the standard frame size for 126 film, as used in the Instamatic cartridge, was 28mm by 28mm, yielding square images, perhaps more suitable for slides; here, the diagonal would have been about 39.6mm; however, the Instamatic Retina Reflex is fitted with a 50mm lens, not, say, a 46mm lens.
Of course, had the world unfolded this way, making SLRs with full-frame sensors would have ended up a greater challenge than it already is, as the area of the sensor would have been 29.6% larger.
Changing the frame width to something shorter than 40mm in order to keep the diagonal the same as that of the 36mm by 24mm frame of 35mm film wouldn't have allowed the use of the same lenses; since the height of a picture would still be 28mm instead of 24mm, and so lenses would require a longer back focus.
Later, the Instamatic brand name was also used for a smaller cartridge containing 110 film, and Pentax made a miniature SLR camera, the Pentax Auto 110, which used that film. This camera is shown at right. However, the interchangeable lenses were all fixed focal length lenses, which sounds incredible; however, given that the camera was so small, a lens focused at "infinity" would still bring anything at any reasonable distance into sharp focus, so that could actually have made sense.
Later, Kodak went still further in this direction with the Kodak disc camera.
35mm film, as used in the Leica and most SLR cameras, had an image area of 36mm by 24mm.
126 film had a basic image area of 28mm by 28mm, although that was usually cropped somewhat during processing; Wikipedia gives the figure of 26.5mm by 26.5mm.
110 film, introduced by Kodak in 1972, had a frame size of 17mm by 13mm. Note that cropping it by a millimetre would lead to 16mm by 12mm, with the motion picture aspect ratio of 4:3.
The image size in the Kodak disc system was 10mm by 8mm, thus larger than that of 8mm home movies at 4.8mm by 3.5mm, or even Super 8 at about 5.8mm by 4mm.
Not only that, but the small size of the frame in the Kodak disc camera system was mitigated by another factor, a recent technical innovation on the part of Kodak.
The image above, from a Kodak advertisement, shows a microphotograph of silver halide grains as modified by Kodak's T-grain process; these flat grains allowed Kodak to produce Kodacolor VR 1000 film, which, as its name suggests, had a sensitivity of ASA 1000, and they also allowed it to give Kodak disc films higher resolution to produce acceptable results with the smaller frame size. A T-grain emulsion was also used to make a version of Kodachrome with ASA 200 available.
On February 1, 1996, Kodak announced the new Advanced Photo System. This used film that was 24mm wide. The size of an image frame was 30.2mm by 16.7mm, but it could be optically indicated on the film that the desired print should instead only make use of a smaller area within that frame; two additional choices were available, 25.1mm by l6.7mm for a "classic" image in a shorter rectangle, or 30.2mm by 9.5mm for a "panoramic" image in a longer rectangle.
If you divide 25.1 by 16.7, the quotient is about 1.503. So the "classic" image is an attempt to match the 3:2 aspect ratio of 35mm SLRs, rather than an attempt to switch from an aspect ratio close to 3:2 to something more like the 7:6 ratio of many large format cameras, which is what I had been expecting at first.
The film speed was recorded magnetically on the film, and optionally cameras could record data magnetically on the film as well, such as an indication of how many frames had been exposed.
The life of this film format was, of course, cut short by the transition to digital photography. However, it left a mark on the era of digital phtography, as full-frame 36mm by 24mm sensors were expensive to make, many digital cameras aiming to be similar to 35mm SLRs used sensors the size of a full APS frame instead.
Even sensors of this size were still expensive, and so budget 35mm SLRs used sensors 17.6mm by 13.2mm, in the "four-thirds" size.
The Konica Autoreflex T was an early and successful product for its maker, establishing Konica as a serious competitor in the SLR marketplace.
However, I was surprised to learn that it had one characteristic usually associated with cheaper cameras from Eastern Europe. The normal lenses available for the camera, instead of having the usual focal length of 50mm, had slightly longer focal lengths.
According to one web site, the choices offered were an f/1.8 lens with a focal length of 52mm, an f/1.4 lens with a focal length of 57mm, and an f/1.2 lens also with a focal length of 57mm.
The mirror in an SLR demands that lenses have a considerable clearance between the back of the lens and the focal point where the image is formed. This complicates lens design, and thus choosing a slightly longer focal length allows making a higher-quality lens at a lower price.
Perhaps the lens I am thinking of is the f/2 lens with a focal length of 58mm; a Biotar lens made by Carl Zeiss Jena had these specs, and so did a Soviet copy, the original Helios-44 lens. Another example of this was also from Carl Zeiss Jena; the Pancolar lens, with an f/1.4 aperture, for Praktica cameras, had a focal length of 55mm. This lens is something of a rare collector's item, as it was made specifically for the Pentacon Super SLR camera. Later on, though, the f/1.4 Prakticar-B lens managed the standard 50mm focal length.
Looking at the history of the double-Gauss lens, though, I learned that several major camera manufacturers reached f/1.4 either first or at a budget price with a lens having a 58mm focal length. The Nikon Nikkor-S Auto from 1959, the Minolta Auto-Rokkor PF from 1961, and two versions of the Topcon RE Auto-Topcor from 1963.
And as late as 1971, Canon went to 55mm for its f/1.2 FD AL lens, and in 1972, Olympus' G. Zuiko Auto-S also went to 55mm to achieve f/1.2.
For that matter, Pentax offered their Takumar f/1.8 lens with a focal length of 55mm.
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The image above is from Wikimedia Commons, licensed under the Creative Commons Attribution Share-Alike 2.0 License France, and is thus available for your use under the same terms. Its author is Rama. |
When back focus is not an issue, then more impressive apertures can be achieved. In 1961, Canon brought out an f/0.95 lens with a 50mm focal length for use on its rangefinder cameras, such as the Canon 7; a Canon 7 with this lens is pictured at right.
Naturally, some other prestigous camera makers found it necessary to compete. Thus, Leica offered its own 50mm f/0.95 Noctilux-M in 1975, Schneider offered their 50mm f/0.95 Xenon in 1970, and Angénieux Paris offered its 50mm f/0.95 Type M1... ah, but that lens is from 1953 (their patent came through in 1955); apparently, it was originally developed for low-light surveillance, not the commercial phography market; I have not been able to find the date when it was first offered to the public.
The principle of a single-lens reflex camera, of course, does not at all depend on the size of film it uses.
The Agiflex dates from 1946; the company that made it had been making basically the same camera during World War II for the use of the British armed forces. It was said to strongly resemble the Reflex Korelle from Germany, but it did not attempt to be an exact copy; I managed to find an image of that camera, which is shown at right, from a British photography magazine from 1936. It took square photographs in the 6x6 format.
Shown at left is the Pentax 6x7, which dates from 1969. It uses 120 roll film, but in design it strongly resembles a typical 35mm SLR, including the pentaprism.
At left here is the Hasselblad 500C, a large format camera which is greatly renowned, or perhaps a later model that resembles it. It was introduced in 1957.
This camera used leaf shutters in its lenses. (And so, at this point, one almost hears the voice of Kodak, proclaiming that its choice of using such a shutter in the Retina Reflex is vindicated.) As is obvious from the photo at left, it eschews a pentaprism, just having a waist-level finder. However, if you really want to take photographs while looking forwards, the PM-90 and PME-90 (the latter including exposure metering) are available as accessories for the Hasselblad 500C to add a pentaprism. There are also accessory 45 degree finders to allow a viewing angle intermediate between that of looking down or looking forwards.
The standard back for the camera carries 120 roll film, but backs which use other types of film are also available for the Hasselblad 500C; it can be made to use Polaroid film, and later in its life a digital back was introduced.
The Hasselblad was used by astronauts on the Apollo moon missions, and other early NASA space missions. It is perhaps best known, however, as the preferred choice for fashion photography, and studio photography in general.
A very few SLR cameras were made that used 127 roll film. The first Exakta cameras, from 1933, did so; later, the Exakta VP, with VP standing for Vest Pocket, and the Night Exakta were versions of the 127 film Exakta. Shown at right is an image from a 1937 advertisement in which both a 127 film Exakta and a 35mm Kine Exakta are shown, the latter being in the foreground. Another was the Komaflex-S from 1960 by Kowa. One possible reason for the relative lack of SLRs in this format is that while Kodak made Kodachrome film available in 35mm and as 620 roll film, it was not available as 127 roll film. Kodachrome was very popular for its vivid colors, but it required a complex procedure for processing, unlike ordinary color films, such as Kodak's own Ektachrome and the color films made by all other companies. Kodak did make Kodachrome film in the 828 format, for use with their Bantam Colorsnap camera, for example.
Kodachrome was the first modern color film, in the sense that it used a subtractive process. Earlier color films, such as Autochrome, used an additive process, which was wasteful of light in exposure and projection, as well as greatly limiting resolution.
Unlike later films, Kodachrome was unique in that the color couplers were introduced to the film by the chemicals used to develop it, rather than being part of the film itself. This made the process for developing Kodachrome much more difficult and complex than that used for later color films. It may have contributed to the longer archival life of Kodachrome film than that of other color films, and this also made the emulsion layers thinner, helping to give the film a higher resolution.
Kodachrome film also had a wider dynamic range than other color films, allowing more highlights and shadows to be visible in color.
While it is remembered for its vivid colors, those colors were also highly accurate as well.
Kodachrome was introduced in 1935, with a speed of ASA 10. It was only in 1961 that Kodachrome II came out at ASA 25, but the very next year, Kodachrome-X provided ASA 64 to the photographer.
In 1936, Agfacolor was introduced. This is a color slide film of the general type that was simpler to develop than Kodachrome; Kodak's first film of that type, Ektachrome, dates from 1946. Fuji Color Film dates from 1948, and Anscochrome, made by an American company that entered the photographic film market, dates from 1955.
Kodacolor, which dates from 1942, was the world's first color negative film used to print photographs on color photographic paper.
Although this page does not have the space to do the subject justice, here are a few examples of images made with different types of color film to give an idea of what is being discussed.
First, this image shows the structure of the colored grains of potato starch that allow an Autochrome photograph to be in color:
Note the unusual choice of additive primaries: red-orange, cyan, and a\ slightly purplish dark blue.
Now, here is an example of a photograph taken by the Autochrome process. As the process of reproducing it on the printed page may have affected its quality for the worse, I have made the attempt to adjust its colors, but the limitation of the Autochrome process, a very narrow dynamic range for the image, should still be visible:
Here is an example of a Kodachrome image. Note the choice of a very demanding subject, three girls dancing in colorful traditional costumes, so that many different shades of red with small differences are visible.
In a booklet showing off the virtues of Agfachrome film, none of the sample images presented were as demanding; still, this sample image seems to show a very good quality of color reproduction.
Before color photography could even be possible, it was necessary to have black and white films which were sensitive to the entire gamut of visible light.
Originally, the chemicals used for making photographic plates could only register blue light. In 1873, orthochromatic plates became available, based on the work of Heinrich Vogel, who used dyes to sensitize the photographic emulsion to green light. This principle was later extended by others to allow photographic plates to register even red light; one date I have seen for the availability of panchromatic plates is 1905, although other sources give earlier dates.
Today, of course, digital cameras have supplanted film cameras almost completely, although film is still used by a small number of enthusiasts.
In 1995, the Casio QV-10 became available. It took pictures with a 320 by 240 resolution, and cost somewhere under $1,000. This was the first digital camera that might be considered to have been accessible to the consumer, but film wasn't quite on the way out yet, with that being the best competition digital could muster.
By 1999, digital cameras with a 2.5 megapixel resolution were available, such as the Olympus C-2500L, a digital SLR, and started to be considered as comparable to film cameras. But it would be a few more years before the prices of digital cameras came down enough to drive film cameras from the market.
Pictured at right is an example of a digital DSLR. This camera, from Nikon, was well-regarded when it was first available, and was an expensive top-of-tphand market, despite having a full-frame sensor (even if that sensor has "only" 12.1 megapixels).
Announced in 2007, it was the first camera with a full-frame sensor that Nikon offered.
The Nikon D200 was an earlier Nikon camera, with a sensor in the Nikon DX format, which was 23.6mm by 15.8mm in size. Note that this is smaller than APS size, 30.2 mm by 16.7mm, but larger than four-thirds size at 17.6mm by 13.2mm. A sensor that was 23mm by 15.5mm in size was used in the Fujifilm Finepix S5 Pro camera, pictured at left; this camera used Nikon-mount lenses because it used the body of the Nikon D200 (although it used different batteries). It was one of the Fujifilm cameras that had a SuperCCD sensor with large octagonal pixels with small square pixels between them, for extra dynamic range.
As one review of a Fujifilm camera with a SuperCCD camera noted, the effective resolution of such a camera is determined solely by the large octagonal pixels, with the small square pixels simply being used to improve the rendering of bright areas in the image. That may have been the fault that led Fujifilm to abandon this sensor type.
Incidentally, the later Nikon D600, D700, and D800 cameras used full-frame sensors.
The Fujifilm SuperCCD sensor was one of the few attempts to replace the standard Bayer sensor used in most cameras with something innovative. Another attempt, which seems to have been less successful, appeared in only one model of camera, the SONY Cyber-Shot F-828, shown at right. This replaced one of the green pixels in the Bayer array with a pixel having a different sensitivity, using a different shade of green, termed "Emerald".
Of course, if we're going to talk about innovation in digital camera sensors, we can't fail to mention the one that was most profoundly innovative of all. That was the Foveon sensor, and the Sigma SD9 camera, pictured at right, is one of those that used it.
Ordinary camera sensors have one layer of cells sensitive to light, with a patterned array of color filters overtop. The Foveon sensor, instead, has a chip which has three layers of photosensitive cells, and the silicon which separates those layers also filters the light that reaches them, so that there are three classes of light detector with different spectral sensitivities, but each pixel has a sensor of each of the three kinds.
This eliminates the need to use interpolation to determine the values of the color components at a pixel location other than that pixel's native color component.
Pictured at left is the Pentax 645Z. This is a mirrorless medium format camera. It has a 51.4 megapixel sensor that measures 43.8mm by 32.8mm. It was preceded by the 645D, which had a 40 megapixel sensor instead, also the same size.
The Fujifilm GFX 50S, shown at right, had very similar specifications to those of the 645Z, a 51.4 megapixel sensor claimed as measuring 43.8mm by 32.9mm. It came out several months after the one from Pentax. The Fujifilm camera had a successor, the GFX 100S, with a sensor the same size, but having twice as many pixels. Like other Fujifilm cameras, it offers a number of film simulation modes, which allow the camera to make pictures resembling those made with various film stocks, from Fujifilm itself and from other makers, and this feature has made their digital cameras quite popular, as it is also available on their less expensive models. And Fujifilm has just now (September 2024) announced its successor, the GFX 100 II.
Pictured at right is another example of a mirrorless camera, the Olympus OM-D E-M1. This camera had a 16 megapixel sensor in the Micro Four-Thirds size (this has an imaging area of 17.3mm by 13mm); it was advertised as being everything that a professional photographer would need, and despite the existence of more expensive cameras with fancier specs, I feel this claim to have been quite justified.
Most of these examples of digital cameras are still several years old, but they still give some idea of what photography is like today.
This page, while it examines cameras of several different types, concentrates mainly on the 35mm SLR.
We have seen above why the first 35mm SLRs generated some excitement, being small and light, and therefore more convenient, and why the pentaprism was a very important development, since it made looking through the viewfinder simple, and similar to the way it was with other types of camera.
But another question hasn't been addressed above at all. In a digital camera, one can view the scene the camera is looking at through a display on the camera. Why do digital SLRs even exist at all?
Well, the digital display on a camera is much lower in resolution than the camera's digital sensor. As well, one film SLR feature not discussed above is that the ground glass in a film SLR usually has a central region with special features designed to aid in focusing the camera. This is one reason why some of the most high-end cameras had removable pentaprisms, because there was a reason why someone might wish to swap out the ground glass plate for one where these special features were differently designed.
So the DSLR did have practical benefits for manual focusing, in addition to fitting in with what people were used to.
Shown at left is a diagram showing the elements of one type of focusing screen. In the center is a small circular area divided into two halves, where the surface of the screen on one side is tilted to the left or right, forming two prisms, which will split vertical lines that are not focused properly.
The next ring outside the center consists of microprisms. A similar principle is involved as in the split image area, but here small prisms in multiple directions mean that only items in focus can be seen clearly.
Then most of the central area consists of a plain ground glass surface, where the image can be seen as it will be, whether in or out of focus, with the out of focus areas simply being blurred as they will be in the final image.
The outside area instead is a Fresnel lens, acting as a field lens, to make the image as bright as possible, although this means that in this area, it is not possible to tell anything about whether items are in or out of focus.
The most common focusing screens on single-lens reflex cameras are of this general type, although they usually omit the split image area, having only microprisms in a central circle.
But optional focusing screens can be of other types; for example, they might consist entirely of plain ground glass, possibly with a reticle pattern marked on the screen as well. At right are shown the seven types of focusing screen available for the Praktica VLC camera; the top row shows a Fresnel lens combined with a split-image rangefinder and then a Fresnel lens combined with microprisms instead. The second row shows a plain ground glass screen, and a ground glass screen with a clear spot with crosshairs. The third row shows a clear screen with a millimetre (on the film) scale, and a ground glass screen with a grid. And the bottom row shows a ground glass screen with the same type of millimetre scale as shown above on a clear screen.