The Leica changed photography

In the October 1936 issue of Fortune, there was an article on the “minicam boom”. It cited there being 100,000 miniature cameras in the US, comprised of more than 30 different makes.

Model E Leica, 1936

“Many a man who had owned a Kodak for years without feeling any impulse to see what he could do with it if he applied himself fancied that in the Leica he was finding a new invention that defied the laws of optics and would give him good pictures with no light to speak of and no effort save that of pressing the button. The Leica didn’t even look like a camera. No bellows, no bulk, no focusing hood; you shot from the hip, so to speak, and got your man.”

“Miniature Cameras”, Fortune, p.125 October 1936

the histogram exposed (i) – unimodal

This is the first post in an ongoing series that looks at the intensity histograms of various images, and what they help tell us about the image. The idea behind it is to try and dispel the myths behind the “ideal” histogram phenomena, as well as helping to learn to read a histogram. The hope is to provide a series of posts (each containing three images and their histograms) based on histogram concepts such as shape, of clipping etc. Histograms are interpreted in tandem with the image.

Histogram 1: Ideal with a hint of clipping

The first image is the poster-boy for “ideal” histograms (almost). A simple image of a track through a forest in Scotland, it has a beautiful bell-shaped (unimodal) curve, almost entiorely in the midtones. A small amount of pixels, less than 1%, form a highlight clipping issue in the histogram, a result of the blown-out, overcast sky. Otherwise it is a well-formed image with good contrast and colour.

Histogram 2: The witches hat

This is a picture taken along the route of the Bergen-Line train in Norway. A symmetric, unimodal histogram, taking on a classic “witches hat” shape. The tail curving towards 0 (①) deals with the darker components of the upper rock-face, and the house. The tail curving towards 255 (③) deals with the lighter components of the lower rock face, and the house. The majority of midtone pixels form the sky, grassland, and rock face.

Olympus E-M5MArkII (16MP): 12mm; f/6.3; 1/400

Histogram 3: An odd peak

This is a photograph of the statue of Leif Eriksson which is in front of Reykjavik’s Hallgrímskirkja. It provides for a truly odd histogram – basically the (majority of) pixels form a unimodal histogram, ③ , which represents the sky surrounding the statue. The tiny hillocks to either side (①,②) form the sculpture itself – the left forming the shadows, and the right forming the bright regions. However overall, this is a well formed image, even though it may appear as if the sculpture is low contrast.

Leica D-Lux 6 (10MP): 14.7mm; f/2.8; 1/1600

Moriyama on clarity

“For me, capturing what I feel with my body is more important than the technicalities of photography. If the image is shaking, it’s OK, if it’s out of focus, it’s OK. Clarity isn’t what photography is about.”

Daido Moriyama

The kit of the mid-century photojournalist

Photojournalism had its origins in the photography of war. Photojournalists are photographers who take pictures that illustrate or tell a story. The first photograph used as an “illustration of a newspaper report”, was a daguerreotype taken by Charles-François Thibault in Paris during the bloody June Days uprising in 1848. Two images were taken at Rue du Faubourg-du-Temple : the scene depicts a barricade on a empty street, at 7.30am on June 25th. On July 8th, the newspaper L’Illustration reproduced the images as woodcuts. Photographic coverage of the Crimean War (1853-1856), and the American Civil War in the 1860s required cumbersome cameras taking long exposures on plates – shots were taken before or after battles because combat coverage was impossible. WW1 brought medium format cameras with glass-plate negatives (these were used by “official” photographers, soldiers used the Vest Pocket Kodak).

Barricades in the Rue Saint-Maur (daguerreotype)
The woodcut from L’Illustration

The Golden Age of photojournalism was considered to be the period of the 1930s through the 1950s, largely due to the introduction of the Leica 35mm camera in 1925. But what sort of kit did the average photojournalist (not including army combat photographers) use in the mid-century period? Being a photojournalist was a demanding occupation. Consider the words of Boris Spremo (1935-2017): “

“I have walked through the wreckage’s of plane crashes and smashed cars . . . knelt beside dying people in Central Africa . . . faced bullets . . . run from tear gas bombs, been chased by angry mobs . . . ridden in a dug out canoe in the sweltering jungles of South America and on dog sleds at 50°C below zero in the Canadian far north . . . ”

Spremo, Boris. Boris Spremo: Twenty Years of Photojournalism. Toronto: McClelland, 1983.

So it is imaginable that a typical photojournalist would want to carry as little gear as possible. In the 1930s, while 35mm had followers, many photojournalists still used large format press cameras. For example Charles Kerlee (1907-1981) in his 1939 book “Pictures With a Purpose – How They Are Made” describes using a 4×5 series D Graflex with a 8¼” Steinheil Cassar lens, or a 40cm Tele-Tessar lens (400mm=135mm, 8¼”=65mm in 35mm equivalency).

Robert Capa (1913-1954), who it is rumoured photojournalist, L.B. “Jeff” Jefferies is based on in the movie “Rear Window” was an icon of photojournalism, covering the Spanish Civil War and WW2. Capa is known for using a Leica at the beginning of his career, including for one of his most famous works, Falling Soldier taken during the Spanish Civil War. But by his coverage of the Chinese resistance to the Japanese invasion in the late 1930s, he had switched to the Contax II series of cameras. In 1944 as he followed allied troops onto the beaches at Normandy (the “Easy Red” sector of Omaha Beach), he carried two Contax cameras. His preference was for 50mm lenses, with a certain liking of the Zeiss 50mm Sonnar f/1.5. When he left on that ill-fated assignment to Indochina in 1954 he carried a Nikon S to complement his Contax.

A Contax II

Horace Bristol (1908-1997) was another American photographer who was best known for his work in Life. After WW2, Bristol settled in Japan, publishing “Tokyo on a five day pass with candid camera” in 1951. Although photographing for a photo-book he describes in detail the type of gear used through the process. It seems Bristol largely used 35mm cameras, typically still known as the “candid camera”. He states that while a telephoto and wide-angle are needed, the workhorse is the 50mm, it will “do almost anything any lens will do”. Photographing for the book, Bristol used an array of cameras, but typically carried a Canon III and Leica IIIc for candid work (likely what we would today term street photography). As to lenses, Bristol carried the following array: Serenar 135mm f/4, Serenar 85mm f/2, Nikkor 50mm f/1.4, Serenar 50mm f/1.8, Serenar 35mm f/3.2 and a Serenar 38mm f/3.5. Of course this sort of photography allowed for greater flexibility (Serenar = Canon).

Photojournalists also typically did not carry the full gamut of lenses. As suggested by Bristol:

“Don’t, however, be lead into the error of thinking that the answer to good pictures is to be found in a complete set of matched lenses. just the opposite is true, for there is a very definite correlation between the number of lenses the average photographer carries, and the worth-while pictures he produces. Unfortunately, this varies in inverse order; in other words, the more equipment to worry about, the fewer pictures of merit!”

Horace Bristol, Tokyo on a five day pass with candid camera (1951)

Many photographers adopted “candid cameras” because they were compact and convenient. W. Eugene Smith (1918-1978) supposedly left Newsweek in 1938 because they wanted him to work with a larger format, but he preferred his Leica. After that he secured a job at Life. Over his career he used many different 35mm cameras, Leica, Contax, Pentax, Nikon. His preference was for 21mm, 28mm, 35mm, 85mm and 135mm lenses. Yevgeny Khaldei (1917-1997), the Ukranian photographer who captured one of the most iconic WW2 photographs of a Soviet soldier raising a flag over the Reichstag in Berlin, used a Leica III throughout his career.

In the end, it is likely that 35mm cameras took over from larger format because they were practical. Practical and efficient, in the fast-paced world that photojournalism was becoming.

Further reading:

Diamonds Are Forever – the Nikon F

In 1971, two of the villains in the James Bond movie, Diamonds Are Forever used a Nikon F to take photos. The question is why the Nikon F? I mean it’s not like it was a new camera. First unveiled in 1959, it was no doubt an influential camera, but a decade later was it still cutting edge?

It was not the only time Nikon cameras were used in movies. The list is actually quite long, including the likes of The French Connection, Jaws, and Apocalypse Now (here’s another list of cameras in movies and TV shows). Nor was it the only camera used in Bond films – Bond used a Rolleiflex T in From Russia with Love (1963), a in Goldfinger (1964), a Nikonos Calypso in Thunderball (1965), and a Minox subminiature in On Her Majesty’s Secret Service (1969).

The Nikon F was at the forefront of SLR technology in the 1960s, and had a wide audience of users, from photojournalists covering the Vietnam War, to NASA. In March 1968 the Nikon F was laboratory tested by Popular Photography. Reviewers found little to complain about, it was an easy camera to function with, and extremely well built, except for the fact that it was heavy, “like a military tank of a camera”. It had a presence which was hard to dispute.

Choosing a camera for any movie may be a mere factor of chance. A personal preference of the director, or somebody facilitating props. Sometimes it’s product placement, although considering the Nikon F2 was released in the same year as the movie, it’s unlikely that is the case.

further reading:

the image histogram (vii) – log histograms

Sometimes a histogram is depicted logarithmically. A histogram will typically depict only large frequencies, i.e. histogram intensities with limited values will not be visualized. The logarithmic form helps to accentuate low frequency occurrences, making them readily apparent. In the example histogram shown below, intensity level 39 has a value of 9, which would not show up in a regular histogram given the scale, e.g. intensity 206 has a count of 9113.

The fastest vintage 50mm lenses ever made – light gathering behemoths

Some of the most interesting vintage lenses are the sub-f/1.2 lenses, of which there are very few. In the 1950s Japanese lens makers wanted to push the envelope, racing to construct the fastest lenses possible. There were four contenders: the Zunow 50mm f/1.1, the Nippon Kogaku’s Nikkor-N.C 50mm f/1.1, Konishiroku (Konica’s predecessor) Hexanon 60mm f/1.2 and the Fujinon 50mm f1.2 LTM. This spurned research which led to the development of the Canon 50mm f/0.95 (1961), which at the time was the largest aperture of any cameras lens in the world. The other, which did not appear until 1976 was the Leitz (Canada) Noctilux-M 50mm f/1.0.

(Note that these lenses were made for 35mm rangefinder cameras.)

Why were these lenses developed?

The most obvious reason was the race to produce fast lenses. An article in the February 1956 issue of Popular Photography sheds more light on the issue. The article, titled “Meet the Zunow f/1.1” [1], by Norman Rothschild, described the virtues of the Zunow lens (more on that below), and concluded with one of the reasons these lenses were of interest, namely that it opened up new areas for the “available-light man”, i.e. the person who wanted to use only natural light, especially with slow colour films. This makes sense, as Kodachrome had an ASA speed of 10, and Type A’s speed was ASA 16. Even Kodachrome II released in 1961 only had a speed of 25 ISO. Conversely, black and white film of the period was much faster: Kodak Super-XX was 200 ISO, and Ilford FP3 was 125 ISO. Ilford HPS, introduced in 1954 pushed the ISO to 800. The newer Ektachrome and Anscochrome colour films were rated at ASA 32. In the patent for the Zunow f/1.1 lens [3], the authors claimed that objectives with apertures wider than f/1.4 were in more demand. In reality, the race to make even faster lenses was little different to the race to get to the moon.

Zunow 50mm f/1.1

The first of the sub-5/1.2 lenses was the Zunow 50mm f/1.1. Teikoku Kōgaku Kenkyūjo was founded by Suzuki Sakuta circa 1930 and worked for other companies grinding lenses. The company started working on fast lens around 1948, with the first prototypes completed in 1950, and the 50mm f/1.1 Zunow released in 1953. It made a number of lenses for rangefinder cameras, including slower 50mm lenses in f/1.3, and f/1.9, a f/1.7 35mm, and a 100mm f/2 lenses. In 1956 it became the Zunow Kōgaku Kōgyō K.K., or Zunow Optical Industry Co., Ltd., but closed its doors in early 1961. During the last years the company designed a couple of camera’s including a prototype of a Leica copy, the Teica, and the Zunow SLR, the first 35mm SLR camera with auto diaphragm, instant-return mirror, and bayonet mount interchangeable lenses (only about 500 were ever produced).

The Zunow 50mm f/1.1 was derived from the Sonnar-type f/1.5 lens. The patent for the Zunow f/1.1 lens [3] describes the lens as “an improved photographic objective suited for use with a camera that takes 36×24mm pictures”. Many of these fast lenses were actually manufactured for the cine industry. For example the company produced Zunow-Elmo Cine f/1.1 lenses for D-mount in 38mm and 6.5mm (and these lenses are reasonably priced, circa US$500, however not very useful for 35mm). The Zunow 50mm f/1.1 is today a vary rare lens. Sales are are US$5-10K depending on condition. The price for this lens in 1956 was US$450.

  • 1953 – Zunow f/1.1 5cm, Leica M39 mount/Nikon S, 9 elements in 5 groups.
  • 1955 – Zunow f/1.1 50mm, Leica M39 mount/Nikon S, 8 elements in 5 groups.

Nikkor-N 50mm f/1.1

Hot on the heals of Zunow was the Nikkor-N 5cm f/1.1 developed by Nippon Kogaku. Introduced in 1956, it was the second sub-f/1.2 lens produced. The lens was designed by Saburo Murakami, who received a patent for it in 1958 [5]. While the Zunow was an extension of the Sonnar-type lens, the Nikkor lens was of a gaussian type. It was also made using an optical glass made using the rare earth element Lanthanum in three of its optical elements. The lens was made in three differing mounts: the original internal Nikon mount (for use on Nikon S2, SP/S3 cameras), the external Nikon mount, and the Leica M39 mount. The original lens mount was an internal mount, and the heavy weight of the lens (425g) could damage the focusing mount, so it was redesigned in 1959 with an external mount. The lens had a gigantic lens hood with cut-outs for setting the focus with the rangefinder through the viewfinder.

  • 1956 – Nikon Nikkor-N[.C] 50mm f/1.1, Leica screw mount/Nikon S, 9 elements in 6 groups (Nikon, 1200 units; M39, 300 units)
  • 1959 – Nikon Nikkor-N 50mm f/1.1, Leica screw mount/Nikon S, 9 elements in 6 groups (1800 units)

A 1959 price list shows that this lens sold for US$299.50. Today the price of this lens is anywhere in the range $5-10K. Too few were manufactured to make this lens the least bit affordable. Nippon Kogaku also supposedly developed an experimental f/1.0 lens for the Nikon S, but it never went into production.

Canon 50mm f/0.95

In August 1961, Canon released the 50mm f/0.95, designed as a standard lens for the Canon 7 rangefinder camera. It was the world’s fastest lens. The Canon f/0.95 was often advertised attached to the Model 7 camera – the Canon “dream” lens. The advertising generally touted the fact that it was “the world’s fastest lens, four times brighter than the human eye” (how this could be measured is questionable). It is Gauss type lens with 7 elements in 5 groups. The lens was so large on the Canon 7 that it obscured a good part of the view in the bottom right-hand corner of the viewfinder, and partially obscured the field-of-view.

In a 1970 Canon price list, the 50mm f/0.95 rangefinder lens sold for $320, with the f/1.2 at $220. To put this into context, $320 in 1970 is worth about $2320 today, and a Canon 7 with a f/0.95 lens in average condition sells for around this value. Lenses in mint condition are valued at around $5K.

The verdict?

So why did these lenses not catch on? Cost for one. While f/1.2 lenses were expensive, faster lenses were even more expensive. For specialist applications, the development of these lenses likely made sense, but for the average photographer likely not. There were a number of articles circa 1950 in magazines like Poplular Photography which seemed to downplay their value, which likely contributed to their decline. It is notable that by the the early 1960s, Nikon stopped advertising its 50mm f/1.1 lens, and never produced another sub-f/1.2 lens. By the late 1960s even Canon had ceased production of the f/0.95.

There were probably more sub f/1.2 lenses created for non-photographic applications, in many different focal lengths. For example x-ray machines (Leitz 50mm f/0.75), D-mount film cameras (e.g. Kern Switar 13mm f/0.9), C-mount for film, medical and scientific imaging (e.g. Angenieux 35mm f/0.95), and aerial photography lenses (e.g. Zeiss Planar 50mm f/0.7). Not until recently have super-fast lenses once again appeared, likely because they are technologically better lenses, made much cheaper than they ever could have been in the 1950s and 60s.

References:

  1. Norman Rothschild, “Meet the Zunow f/1.1”, Popular Photography, pp.126/128, February (1956)
  2. Kogoro Yamada, “Japanese photographic objectives for use with 35mm cameras”, Photographic Science and Engineering 2(1), p.6-13 (1958)
  3. U.S. Patent 2,715,354, Sakuta Suzuki et al., “Photographic Objective with Wide Relative Aperture”, August 16, (1955)
  4. Hagiya Takeshi, Zunō kamera tanjō: Sengo kokusan kamera jū monogatari (The birth of the Zunow camera: Ten stories of postwar Japanese camera makers) Japanese only (1999)
  5. U.S. Patent 2,828,671, “Wide Aperture Photographic Objectives”, April 1, 1958.

Further reading:

Why don’t cameras use plastic lenses?

The term plastic is somewhat relative – it actually means any material that is moldable, shapable, ductile. At extremely high temperatures even rocks can become plastic. The most common use of the word is likely to describe a synthetic material made from a wide range of organic polymers. The first plastic made from synthetic materials was Bakelite, which was invented in 1907. It was used in the 1930s to make cameras such as the Kodak Baby Brownie, and Purma Special. Plastic materials such as methyl methacrylate, or acrylic (often better known by its trade names, e.g. Lucite, Plexiglas, Perspex), were developed in the 1920s, largely to make unbreakable eyeglasses.

There was little interest in the use of plastics as substitutes for optical glass until WW2. Many plastic materials were examined during the war period, but few were found to have the right optical characteristics for use in photographic lenses. After the war, research continued, and plastics replaced glass in a number of non-critical optical purposes. But in the realms of photography, few if any manufacturers gave up their dependence on glass, save perhaps for lenses in inexpensive box-cameras. In 1946 Andrew Hecht wrote an article on plastic lenses [1]. The first statement he made was “Plastic lenses are here, and they are here to stay…”. Hecht suggested they would only be economical in lenses of 2.5” or more in diameter. The article focuses on Thomas S. Curtis Laboratories, which produced thousands of lenses up to 18” in diameter for the US Army. These lenses were manufactured from large slabs produced in electric furnaces which is then cut, and shaped on lathes, ground and polished. The article seemed to focus on lenses for applications such as industrial magnifiers.

The HOLGA 120N and DIANA cameras with plastic lenses

The 1950s saw a growing trend towards the idea of using plastics in cameras. In 1952 Kodak was experimenting with plastic viewfinders in its simple cameras, and by 1957 was making injection molded meniscus lenses for use in snapshot cameras. In 1959 it was using triplet lenses with an f/8 aperture in its Starmatic Brownie cameras. The March 1961 issue of Modern Plastics [2] had an article on plastic lenses, with a cover touting “Lenses – The Focus is on Plastics”. The article describes large plastic lenses made of acrylic, 4-30” in size, used in applications such as magnifiers and reflectors. The article described the many benefits of plastic lenses: reduced weight, more light transmission, impervious to thermal shock, and chip-proof. However of the varied applications it suggests the “prospects are not overly bright for injection molded methacrylate”, largely due to the refractive index. Doubts had already started to set in.

Lloyd Varden investigated plastic lenses in the August 1961 of Popular Photography [3]. He describes a long list of properties that glass had that made it superior to plastic: (i) range of refractive indexes, and dispersion values available, (ii) homogeneity, (iii) physical hardness, (iv) transparency, (v) selective absorption, i.e. absence of colour, (vi) light and atmospheric stability, (vii) freedom from excessive bubbles, (viii) thermal expansion, (ix) moisture absorption, (x) chemical reactivity and solubility, and economy in manufacturing. Unfortunately, plastics of the period could not match up to all these requirements. Plastics could have a high degree of transparency, a low selective absorption, and an absence of bubbles, but failed in other categories such as physical hardness, making them susceptible to scratches, or a high refractive index/low dispersive power.

In 1964 Leonard Lipton wrote Popular Photography article, again looking at plastic lenses: “Plastic Lenses: Good Enough!” [4], in which he said “we are already deep into the plastic lens revolution.” He estimated that in 1963 five million plastic lenses were manufactured, and good photographic objectives could be made up to f/8. He suggests that Kodak was reluctant to admit their inexpensive cameras contained plastic lenses, largely due to the perception that the public associated plastic with an inferior product. Kodak instead preferred to use the term “acrylic”. Many companies were at the time using plastic in products such as viewfinders, and slide viewers. Lipton’s article was a lengthly one, describing the virtues of plastic (over glass), how plastic has dealt with issues such as striation, and changes in temperature, the process of molding lenses, and their limitations.

Plastic lenses are typically molded from polymers such as methyl methacrylate (MM), and styrene acrylonitrile copolymer (SAC). Optical glass is chemically nothing like optical grade plastic. Plastic has a definite molecular structure, whereas glass does not. Plastic is basically made from carbon, hydrogen and oxygen, whereas glass can contain a wide variety of materials, e.g. silicon dioxide, barium, boron, lead, and even thorium. The single biggest benefit of plastic is that it could be injection molded. Glass on the other hand, could not be injection molded as it would produce surface irregularities, which would then have to be ground and polished out (modern glass can be precision moulded). Injection molding allowed for complex shapes to be made easily, and inexpensively. Early plastic lenses suffered from something called “striation” whereby a lens has regions which with an index of refraction different from the rest of the lens, resulting in fuzzy pictures. It was caused by uneven cooling in the mold, but by the mid-60s this had been eliminated from lenses.

Plastics were said to suffer from defects, e.g. becoming pitted, or discoloured. However as they were usually used in simple, small lenses, this was hardly ever a real issue. Scratching (of the outer lens) was reduced through the use of plastics like Plexiglas V100, another acrylic which is very hard. The biggest issue with plastic lenses centred around the index of refraction (IR), which is a dimensionless number that indicates the light bending ability of a medium. The IR of plastics was (and is) rather low compared to optical glass. Acrylic has an IR of 1.49, and styrene acrylonitrile copolymer, 1.57. Compare this against modern glass of the period, at 1.52 to 1.89. Another problem was the fact that the IR of acrylics decreases as temperatures increases, changing the focus. Some plastic lenses were designed to automatically compensate for this. For example the plastic f/8 Cooke triplet, which used lens elements made from both acrylic and SAC. The focus of the acrylic elements (front and rear) increases, while the focus of the middle SAC lens decreases, balancing out any changes in focus.

The plastic lenses: Cooke triplet and the single lens

Lipton went a long way to describe the manufacturing benefits of plastic (and the drawbacks of optical glass) [4]. Optical glass is made by melting raw materials, which is processed when it cools into glass. Optical glass requires a number of steps including grinding, polishing, and testing, which made them expensive to manufacture. Plastic lenses on the other hand were simple to manufacture:

“Plastic lenses are made in air conditioned pressurized rooms, and in the case of Plexiglas or Lucite, the plastic, in powder form, is fed to a machine where it is heated and softened. It may be heated to a temperature of 400 to 500 degrees Fahrenheit. The softened plastic is then forced, under a pressure of at least 16,000 pounds per square inch, into a mold when it remains until it cools enough to retain the mold’s shape. The mold is then opened, and the lens is popped out, ready to be used as is, or assembled with other elements with no necessity for working to a finished size.”

Not that manufacturing optical plastics didn’t have its limitations. It was challenging to mold large diameter optical lenses, lenses with plane surfaces, and those with thick centres and thin edges. Lipton considered two stumbling blocks prohibiting the creation of high-speed 35mm lenses: low refractive indices, and the inability to mold large diameter lenses. In fact Dr. Rudolf Kingslake, director of optical design for Kodak, said of plastic objectives: “It’s the low indicies of refraction that are stopping us, it’s just a matter of substituting plastic for glass.”[4].

In 1972 Bob Schwalberg wrote an article describing why glass still reigned supreme [5]. He suggested SLR pentaprisms were a good candidate for conversion to acrylic which would reduce production costs. Schwalberg outlines five benefits:

  1. Lower cost – Raw materials are cheaper, and less expensive to work.
  2. Complete form freedom – Aspherical (non-spherical curvature) lenses are expensive to make in glass.
  3. Exceptional clarity – Not all optical glass is perfectly colourless, the highest grades of optical plastics are quite colourless, and their clarity frequently superior.
  4. Light weight – Plastic lenses are lighter.
  5. High impact resistance – Glass is brittle, plastics are flexible.

and five counter-arguments:

  1. Too limited range of optical specifications – i.e. The refractive index, and the dispersion. Refractive indexes for optical plastics are close to 1.5, optical glass ranges from 1.42 to 1.95.
  2. Poor curve holdability – Accurate lens curvatures are critical for quality performance. Plastic lenses have poor curve conformity because of (3) below, and their inherent flexibility. Glass is stronger and more stable, it holds curvature much better in the face of external forces.
  3. High temperature coefficients – The expansion and contraction of optical plastics is much greater than for optical glass. Muti-element plastic lenses have been developed with elements possessing opposing temperature coefficients. Unthinkable for precision camera lenses.
  4. Clear plastics are hygroscopic – They absorb airborne moisture. Optical media must be isotropic, i.e. equal in all directions. The absorption of moisture destroys this homogeneity.
  5. Low abrasion resistance – Plastics are softer and more prone to scratching than optical glass.
The Kodak Starmatic and its lens

Many of the cameras that use(d) plastic lenses are considered to be “toy” cameras. In 1959 Kodak introduced the Starmatic, the top of Kodak’s Brownie line. It had an 44mm f/8 three-element, plastic lens. The Lomography Diana appearing in the 1960s, and was made entirely of plastic (and in 1975 cost less than $2). The Polaroid Pronto Land camera (mid 1970s), also had a 116mm 3-element Polatriplet plastic lens. Most Holga cameras, had a 60mm f/8 plastic meniscus lens.

But the breakthroughs and sophisticated designs associated with plastic lenses never really materialized. In the end, low refractive indices, and the inability to successfully mold large diameter lenses may have been stumbling blocks to making 35mm lenses from plastic. There are some plastic optical materials [6] that have reached a refractive index of as high as 1.68, e.g. PolyEtherImide, but they often suffer from having a lower transmission rate (36-82% for PolyEtherImide, versus 92% for acrylic). Leica APO glass, on the other hand, has a refractive index of 1.9005.

Apart from their use in inexpensive cameras, there is another use of optical plastic, that is in hybrid aspherics. A hybrid aspherical element is a lens element consisting of a glass base upon which plastic is glued, creating the desired aspheric shape. They are typically used in zoom lenses, e.g. the Nikon 28-70mm f/3.5-4.5 AF, first introduced in 1991. Companies like Tamron use hybrid aspherical lenses, likely to reduce the cost of the lenses. Lipton somewhat predicted this use in 1964 [4] when he suggested it would be difficult to grind an aspheric lens in optical glass, yet the manufacture of aspheric lenses in plastic would be no problem. Ironically, many smartphones have lenses which are actually plastic. This is not surprising considering the small size of the lenses required for mobile devices – it is less of a technological challenge, and hence costs less to manufacture (but as manufacturers don’t publish lens diagrams, it’s hard to know). For example the Leica lenses used in Huawei smartphones are plastic. Are there smartphones with glass elements? Sure, but they are usually quite expensive.

Ultimately the inability to derive high precision optics is one of the reasons we don’t see more plastic lenses. But there is another, human factor involved in companies shying away from the use of plastics – the perception of quality. Glass is more associated with quality that plastic, whereas plastic is considered “cheap”, and disposable. This is largely due to its use in inexpensive cameras, and the stigma attached to plastic itself.

  1. Andrew B. Hecht, “And Now Plastic Lenses”, Popular Photography, 18(5) pp.72-74,128 (1946)
  2. “Learn from Lenses”, Modern Plastics, 38(7), pp.90-93 (1961)
  3. Lloyd E. Varden, “Plastic Lenses”, Popular Photography, 49(2) p.48,97,98 (August, 1961)
  4. Leonard Lipton, “Plastic Lenses: Good Enough!”, Popular Photography, 55(2) p.44-45,100-101 (August, 1964)
  5. Bob Schwalberg, “Plastic optics vs. glass, and why glass still reigns”, Popular Photography, 70(2) p.52,118 (1972)
  6. Kingslake, R., Johnson, R.B., “The Work of the Lens Designer”, in Lens Design Fundamentals, 2nd ed. (2010)
  7. C.B.Estes, Thermally Compensated Plastic Triplet Lens, (July 24, 1961), Eastman Kodak Company, U.S. Patent No. 3,205,774

Further reading:

Rear Window – the 400mm lens

In a previous article, I discussed the Exakta VX camera used in Alfred Hitchcock’s “Rear Window”, suggesting that photojournalists of the period likely didn’t use super-telephoto lenses all that often (or at all). My view on this is based largely on articles I have read in magazines like Popular Photography during the 1950s.

The telephoto lens used by Jefferies in the movie is the Kilfitt Fern-Kilar f/5.6 400mm lens. The lens fits into the category of super-telephoto lenses with focal lengths in the range of 300-600mm. A number of manufacturers produced these lenses, although in all likelihood they had a narrow market. One of the earliest ads for Kilfitt lenses in Popular Photography appears in 1953, advertising their KILAR lenses for “medium and long tele shots” – it includes the 300mm and 400mm lenses. A review of the ads section of Popular Photography in 1954 reveals that the Kilfitt 400mm was being sold alongside the f/5.5 Hugo Meyer-Goerlitz Tele-Megor (which was the lens promoted by Exakta as well), and the Astro f/5.

The Kilfitt-Fern-Kilar 400mm f/5.6

Literature from Heinz Kilfitt Optische Fabrik suggests the lens could be used for “nature and expedition photography“, and also for “special press and feature assignments“. It is then likely that these long lenses were used in situations where a large kit could be carried. Some may argue that Jeff used the lens for sports photography, but that is unlikely, as many photojournalists tended to focus their careers on a particular genre of photography. For example Robert Capa, upon who Jefferies character is loosely based, worked predominantly in war zones: the Spanish Civil War, WWII, Palestine, and the war in Indochina (where he was killed by a landmine). In 1951 Bruce Downes wrote an article in Popular Photography, describing David Douglas Duncan’s photo coverage of the Korean War [2]. He photographed the carnage of war using two Leica IIIc’s, “practical combat cameras” that were “…light, compact and could stand a beating.”. From the perspective of lenses, he used Nikkor lenses: a 50mm f/1.5, a 85mm f/2 and a 135mm f/3.5. No large telephoto lenses in sight.

A steady telescope

In addition, even sports-photojournalists did not generally use long-tele lenses. Jesse Alexander (1929-2021), a motor-sports photographer, reportedly did not use long telephotos lenses. At the start of his career in early 1950s (his first photographic assignment was the 1953 La Carrera road race in Mexico), he used a Leica with 35mm and 135mm lenses, and a Rolleiflex for close-ups and portraits. I would suggest that the 400mm lens was either something Jefferies used occasionally, perhaps for some hobby photography, or merely something added to meet the needs of film. The only real evidence of Jefferies taking sports shots is the motor racing shot that ended up with Jefferies stuck in his apartment with a broken leg. The camera used there was a large format camera (most likely a Graflex), as evidenced by the photo hanging on the wall, taken in the middle of the racetrack.

Identifying the lens

The biggest elephant in the room with these telephoto lenses is their weight. The f/5.6 400mm lens weighed 62oz, or 1.76kg in weight. The faster Sport-Fern-Kilar f/4 400mm lens was even heavier, at 3.1kg. These lenses were just too heavy for a photojournalist to carry and use effectively in an active situation, e.g. a war zone. Even in everyday settings, the length of the telephoto would require the use of a tripod, otherwise shake will be greatly exaggerated – “A slight jiggle that would not be noticed if the scene were filmed with a standard lens will look like something shot on a pogo stick when you use a long telephoto lens.” [1]. It might be okay to use as a de facto telescope and prop up on your knee.

The interesting thing about Exakta is that their literature touted the idea of attaching a telephoto lens to a camera and turning it into a telescope – “a telescope that gives you long-range viewing with high magnification“. A 400mm telephoto lens would provide an eight-power photo-telescope.

NB: Sometimes it is speculated that the lens was actually an Astro-Berlin, a German company that made some pretty cool lenses, especially for the super-super telephoto (we’re talking 2000mm, f/10). These telephotos were often seen on Exakta cameras, hence the association.

  1. Herb A. Lightman, “Choosing and using lenses”, Popular Photography, 35(3), pp.107-117 (1954)
  2. Bruce Downes, “Assignment: Korea”, Popular Photography, 28(3), pp.42-51, March (1951)

the image histogram (vi) – contrast and clipping

Understanding shape and tonal characteristics is part of the picture, but there are some other things about exposure that can be garnered from a histogram that are related to these characteristics. Remember, a histogram is merely a guide. The best way to understand an image is to look at the image itself, not just the histogram.

Contrast

Contrast is the difference in brightness between elements of an image, and can determine how dull or crisp an image appears with respect to intensity values. Note that the contrast described here is luminance or tonal contrast, as opposed to colour contrast. Contrast is represented as a combination of the range of intensity values within an image and the difference between the maximum and minimum pixel values. A well contrasted image typically makes use of the entire gamut of n intensity values from 0..n-1.

Image contrast is often described in terms of low and high contrast. If the difference between the lightest and darkest regions of an image is broad, e.g. if the highlights are bright, and the shadows very dark, then the image is high contrast. If an image’s tonal range is based more on gray tones, then the image is considered to have a low contrast. In between there are infinite combinations, and histograms where there is no distinguishable pattern. Figure 1 shows an example of low and high contrast on a grayscale image.

Fig.1: Examples of differing types of tonal contrast

The histogram of a high contrast image will have bright whites, dark blacks, and a good amount of mid-tones. It can often be identified by edges that appear very distinct. A low-contrast image has little in the way of tonal contrast. It will have a lot of regions that should be white but are off-white, and black regions that are gray. A low contrast image often has a histogram that appears as a compact band of intensities, with other intensity regions completely unoccupied. Low contrast images often exist in the midtones, but can also appear biased to the shadows or highlights. Figure 2 shows images with low and high contrast, and one which sits midway between the two.

Fig.2: Examples of low, medium, and high contrast in colour images

Sometimes an image will exhibit a global contrast which is different to the contrast found in different regions within the image. The example in Figure 3 shows the lack of contrast in an aerial photograph. The image histogram shows an image with medium contrast, yet if the image were divided into two sub-images, both would exhibit low-contrast.

Fig.3: Global contrast versus regional contrast

Clipping

A digital sensor is much more limited than the human eye in its ability to gather information from a scene that contains both very bright, and very dark regions, i.e. a broad dynamic range. A camera may try to create an image that is exposed to the widest possible range of lights and darks in a scene. Because of limited dynamic range, a sensor might leave the image with pitch-black shadows, or pure white highlights. This may signify that the image contains clipping.

Clipping represents the loss of data from that region of the image. For example a spike on the very left edge of a histogram may suggest the image contains some shadow clipping. Conversely, a spike on the very right edge suggests highlight clipping. Clipping means that the full extent of tonal data is not present in an image (or in actually was never acquired). Highlight clipping occurs when exposure is pushed a little too far, e.g. outdoor scenes where the sky is overcast – the white clouds can become overexposed. Similarly, shadow clipping means a region in an image is underexposed,

In regions that suffer from clipping, it is very hard to recover information.

Fig.4: Shadow versus highlight clipping

Some describe the idea of clipping as “hitting the edge of the histogram, and climbing vertically”. In reality, not all histograms exhibiting this tonal cliff may be bad images. For example images taken against a pure white background are purposely exposed to produce these effects. Examples of images with and without clipping are shown in Figure 5.

Fig.5: Not all edge spikes in a histogram are clipping

Are both forms of clipping equally bad, or is one worse than the other? From experience, highlight clipping is far worse. That is because it is often possible to recover at least some detail from shadow clipping. On the other hand, no amount of post-processing will pull details from regions of highlight-clipping in an image.