5
Film
If you look at a cross section of film under the microscope, you can see that it consists of multiple layers. First, there is the film base. Early types of film often had a base of highly flammable celluloid that made photography and storing film somewhat dangerous. Today, film does not explode any more because triacetate and polyester are used as film bases, instead.
During production, the film base is coated with several very thin layers of emulsion containing light-sensitive silver halides suspended in gelatin. Even black-and-white film usually has several layers of differently sized or individually shaped silver halides that serve to make the best use of the light. In addition to the light-sensitive emulsion layers, there are also protective layers and usually an anti-halation layer.
The anti-halation layer absorbs light that would otherwise be reflected back onto the film by the film base or camera back wall, causing light edges (halation or halos) around the lights in the film. Depending on the film, the layer is applied to the back of the film or between the film base and the emulsion. The anti-halation layer increases the contrast options of the film considerably. There are also special types of film that either deliberately omit this layer for artistic reasons (they are referred to as AURA) or that have an anti-halation layer that is not particularly effective (for example Lucky, from China), so they tend still produce highlight halos.
At one time, there was no gelatin of good enough quality for film production available in the United States, so for a while, Kodak became one of the largest operators of cattle ranches in the U.S.
Medium and large format film has an additional backing layer for stability. Plus, some manufacturers coat their film with an anti-curling layer to prevent excessive curling during the drying stage. All the emulsion layers of a black-and-white film taken together are about ten times thinner than a human hair.
Color film is even more complex in structure than black-and-white film, color film has separate layers for the colors cyan, magenta, and yellow, and these in turn each consist of two or three differently light-sensitive layers. Plus there are several filter and correction layers: the anti-halation layer, the protective layer and, depending on the film type, a backing layer, and perhaps a layer to prevent curling. A color film can have 10 to 20 layers and still be only several micrometers thick.
http://www.makingkodakfilm.com/ A fascinating book on film production with many insights into the manufacturing process.
Schematic structure of a black-and-white film (not to scale)
Schematic structure of color film
5.1Black-and-White Film
If you decide to work with black-and-white film, the choice of film plays just as significant a role as the exposure settings on your camera. Depending on the aesthetic criteria that matter to you, or which style best suits your way of shooting and your favorite subject, it’s worth playing around with the different types of film and finding out which one is best for you.
Each different film will have a different look in terms of the grain and tonal value characteristics, sharpness, contrast, ISO value, and nominal film speed. The interplay with different types of developer are another aspect to consider in terms of the film you chose. The question of which range of the light spectrum the emulsion is sensitive to is more important than the brand or manufacturer of the film. The way in which the film is sensitized has a great deal of influence on how the colors we perceive are rendered as shades of gray.
Film types and their spectral range
The human eye has its strongest spectral sensitivity in the yellow-green range. A photographic emulsion in which the silver grains have not been sensitized with embedded color particles is mostly color blind—it’s only sensitive to the short-wavelength spectral range, around 380–420 nanometers (i.e., to blue light). Only subjects that reflect light of this wavelength are rendered in gray tones.
5.1.1From Color to Black-and-White
Whether we are shooting digital or analog, or using color film or black-and-white film, the world around us is in color. The visible spectrum we perceive with our eyes is in between short-wave ultraviolet (UV) light and long-wave infrared (IR) thermal radiation. In between lies the complete rainbow, from violet and blue to green, yellow, orange, and red. This corresponds to wavelengths of about 380 to 780 nanometers.
The spectral areas of light
If we load a black-and-white film today, it will render the visible colors in as many shades of gray as there are shades of color perceptible to our eyes. That was different in the early days of photography. The early types of film were only sensitive to a fraction of the visible spectrum.
The white sunlight (color temperature around 5800 K) reaches us through a huge color filter—the atmosphere. Not all parts of the visible light spectrum can make it through the atmosphere evenly, so the color of the sunlight we see changes constantly. This is particularly noticeable in the morning and in the evening, when the sun is low in the sky and the light has to travel farther through the atmosphere.
Even many modern black-and-white films render red quite dark and blue lighter than yellow
5.1.2Orthochromatic Film
The name for this black-and-white film is derived from the Greek (orthos = right and chroma = color). An orthochromatic emulsion is highly sensitive to blue light, but by adding organic coloring, it has been sensitized to green and yellow light, as well. Light with a wavelength between 400 and 600 nanometers is rendered in shades of gray. As orthochromatic film is blind to red light, red objects are rendered black. An advantage of this insensitivity to red is that this type of film can be developed by inspection in red darkroom light, so you can see what you are doing. Orthochromatic film usually has a fine resolution with high contrast (Ilford Ortho+, Rollei Ortho 25, wephota Ortho 25, and Adox Ortho 25).
Telekia Speciosa. Example of a plant shot on orthochromatic film. Graflex Crown Graphic on wephota Ortho 25.
Incidentally, in the early days of film, this red blindness was the reason why actors and models had to wear different makeup than today. Red lips would have been rendered as black without special makeup, and red cheeks also looked dark. To achieve a more natural looking grayscale representation on film, actors wore blue and green makeup. Camera-people and directors had to use blue filters to be able to render the color red on film.
Green, red, yellow, blue: bocce balls on orthochromatic film
The same scene as a smartphone snapshot
5.1.3Panchromatic Film
Panchromatic means: sensitized to all visible light colors. While orthochromatic film is insensitive to red light, panchromatic film can render red objects in shades of gray because it is also sensitized to light wavelengths of up to 660 nanometers (in special cases, up to 750 nanometers; then it’s sometimes referred to as super-panchromatic film), i.e. orange and red. Unlike orthochromatic film, classic panchromatic film has a slightly reduced sensitivity in the blue and green areas of the spectrum (490 to 540 nanometers). But the latter is still so strong that sky is often rendered very bright and clouds are hardly visible. If you are planning to use this type of film in landscape photography, you should consider using a yellow or orange filter. This will darken the blue sky and increase the contrast to the white clouds. Examples of panchromatic film are Tri-X 400, Kodak TMAX, Agfa APX, Ilford HP5, and Ilford FP4.
Field near Salem. Example of landscape shot on panchromatically sensitized film. Pentax 67 on Kodak Tri-X 400
Compared to the human eye and its predominant sensitivity in the yellow-green range, panchromatic film is more strongly sensitized in the red range. Film that shows reduced sensitivity in the red range of the spectrum—similar to the human eye—is referred to as orthopanchromatic or rectepanchromatic. Unlike orthochromatic film, red and black are not rendered as the same dark shade (Fuji Neopan 100 Acros, Adox CHS 100 II).
Wadden Sea. Example of landscape shot on orthopanchromatic film. Pentax 67 on Fuji Neopan Acros 100.
Another variety of panchromatic film has greater sensitivity in the red range. These films, referred to as super-panchromatic, are sensitized in spectrum ranges of 680, and sometimes even up to 750, nanometers. They were originally designed for use in (warm) lightbulb light. When using dark red filters, you can sometimes even observe infrared-like effects, such as white foliage against almost black water surfaces.
This is an example of a shot on super-panchromatic film. You can see the increased contrast caused by push processing, without losing detail in the shadows. Pentax 67 on Rollei R3 at ISO 1600.
Most super-panchromatic film (with the exception of Rollei Retro 80 S) is frequently available as medium- or higher-sensitivity film (ISO 200 to 400). (Rollei R3, Rollei Superpan 200, Ilford SFX 200, and Foma Retropan 320 soft new are sadly no longer available.)
With the introduction of panchromatic film, it also became necessary to add a cover so you could close the red window for counting the exposures. Otherwise, the numbers printed on the backing paper of the film could be exposed onto the red-sensitive film by the light shining through the little window.
Zeiss Ikonta with red window cover open
Zeiss Ikonta with red window cover closed
5.1.4Infrared (IR) Film
Classic panchromatic black-and-white film that is sensitive from the ultraviolet to red range of the spectrum is designed to render pictures as we visually perceive them. By using filters, you can manipulate how the tonal values are rendered, but you will not be able to achieve the dramatic effects that are possible when using infrared film. Infrared film is generally sensitized to the full light spectrum, but its sensitivity also goes into the infrared range, as the name indicates.
What sets this film apart from normal black-and-white film is how it records heat radiation. This is most noticeable in spring and early summer, when plants grow the most and a lot of photosynthesis takes place. A waste product of photosynthesis is heat or infrared radiation, and on films that have been sensitized to infrared rays, this increased heat generation results in better-defined shadows under trees and around dense vegetation. You can use IR film like normal black-and-white film and make use of this property, for example, when shooting gardens. Manufacturers usually specify on the packaging the nominal film speed for using this film without an IR filter.
The black filter blocks out the light
If you use a black filter (actually, it’s a very dark red filter), which blocks out visible light and only lets through infrared light of bigger wavelengths (depending on the type, >700nm), you can observe what’s referred to as the Wood effect (named after a person, not the material): green plants in sunlight are rendered almost white, and water areas or blue sky are rendered black. This effect produces dramatic pictures with strong contrast.
photo: Heinz Wille
5.1.5Infrared (IR) Film with Aura Effect
Certain infrared film brands, such as the Efke IR 820 aura, do not have an anti-halation layer. This can result in light reflection on the film base, which causes a halo or aura around the highlights. You can use this effect creatively, with or without the filter.
Backyard in Vienna, Graflex Crown Graphic on Efke IR 820 aura
In film without an anti-halation layer, the film base can act as a light conductor. This can cause light to leak into the film cartridge from outside, for example via the front film edge, and partially expose the first few negatives. To avoid this, you should always load this type of film in the dark.
In the following table, we introduce a few common types of black-and-white film with their properties and areas of application.
Black-and-White Film
5.1.6Color Filters
Depending on which film you choose and its particular spectral sensitivity, color will be rendered as shades of gray in different ways. In early photographs, when film was almost exclusively sensitive to blue light, you could, for example rarely see clouds in the sky. The orthochromatic film was unable to distinguish between blue sky and white clouds. Even today, blue light is almost always rendered brighter than green or red tones. That’s why we like to use filters in front of the lens in black-and-white photography, to prevent parts of the blue spectrum from reaching the film.
Photo with red filter
With a red filter, you get a dark or almost black sky with a great contrast to the white clouds. Plus the red filter increases the distance vision. To get a weaker version of this effect, you can use an orange or yellow filter.
Today, color filters (“gels”) are made of glass, polycarbonate, or plastic foil. Older color filters (e.g., Kodak Wratten) were made of gelatin and had to be kept absolutely dry. The term gel for filter foil goes back to that time of gelatin filters, and is still used today.
Color filters and gelatin filters
Light Metering with Color Filters
Color filters extend the exposure because they always result in a reduction of incident light. A red filter, for example, blocks out blue and green light. We need to factor in this light loss in our exposure metering. Many manufacturers specify a filter factor—the correction factor by which you need to extend the exposure—for their filters. A factor of three means adjusting by three aperture stops, so a measured exposure time of 1/200 second is reduced by 3 stops to 1/25 second.
If you cannot find a specified factor, here is a table with a (very approximate) rule of thumb for correction factors:
Proceed as follows: measure the exposure as usual, and then correct the value by the number of stops shown in the table. If your specific filter produces results that are too dark or otherwise unsuitable, do a small exposure bracketing and then remember the correction value that provides the best photo taken with this filter.
Some photographers measure the exposure through the filter to factor in the light loss during metering. That can work, but depends to a certain extent on the spectral sensitivity of the processing meter and how much it matches the speed of the film used. We have had some unexpected results, particularly when using red filters.
5.2Color Film
While black-and-white film offers a wealth of film speeds, processing options, and creative variations, the processing methods for color film are much more standardized. The commonly used method of developing color film has been designed for industrial mass processing. In 1996, the German industrial photo lab CEWE processed more than 2 billion color pictures alone (according to their own statistics). The only way to cope with such quantities is to fully standardize the processes involved.
In industrial labs, the day with the highest throughput was always the Tuesday after the holidays. The holiday film rolls were handed in to the drugstore on Monday morning, and arrived at the lab for processing on Tuesday.
5.2.1Color Negative Film
Over the years, different standardized color processes have become established. Today, only the C-41 process is left. All C-41-rated color negative films, regardless of the brand, can be machine-processed fully automatically in suitable chemicals. Processing times and even temperatures are normed. The associated processing machines were integrated and compact enough (a footprint of less than ten square feet) for local use. Processing and enlarging a color film (“dry to dry”) could be carried out within one hour.
For manual processing, you can get press kits. These are differently sized packets with all the chemicals you need for processing color film at home. Color negative film consists of several layers of color emulsion and filters that interact during the exposure, and divide the picture into its yellow, magenta, and cyan parts. The three light-sensitive layers contain silver halides, just as in black-and-white film. In addition, the color film has dye couplers that form color in the relevant places when the exposed silver is processed.
The color film undergoes a special bleach bath after processing (usually a combination of bleach bath and fixer, also known as “blix” (bleach + fix), which removes the black (exposed) silver and only leaves the colors in the film. Color film is also referred to as grain-free because the bleaching removes the silver image completely.
If need be, you can also process color film with black-and-white chemicals. The result is a (very dense) black-and-white image that usually scans reasonably well.
If you look at a processed color negative film, you will notice its orange tint. This is caused by a combination of different mask dyes that the film contains to compensate for color errors. The analog color enlargement process is matched to this mask so the prints look color corrected. In digital post-processing, this mask can get in the way, and will need to be color corrected after scanning. In contrast to color positive film (slide film), color negative film has a great exposure tolerance and usually forgives exposure errors of several aperture stops.
The orange mask often causes color issues in the analog-digital hybrid process. Rollei offers a daylight color negative film, the Digibase CN 200, which managed to eliminate this mask. After scanning, you no longer have to make complex color corrections.
Orange mask, Kodak Portra 160
5.2.2Slide Film
The reversal of the image is a typical process in film photography. Anything that’s black on the film is going to be white on the finished picture through exposure or digital reversal. That’s not the case with a reversal film, with which the negative is reversed directly onto the film to get a positive image again.
The layer structure of reversal film (also referred to as color positive, slide, or transparency film) is almost identical to that of negative film. Today, slide film is developed using the E6 process. An additional reversal step in processing turns the negative into a positive image.
Canyonlands National Park, Graflex Crown Graphic on Fuji Provia 100F
While color negative film shows an enormous exposure latitude and can easily handle incorrect exposures of up to several aperture stops, slide film is much more sensitive. To avoid demanding too much or too little from its low contrast range during the shot, the exposure should be absolutely spot-on. You will be rewarded with brilliant colors and a vibrant picture. Precise exposure is even more important when showing the pictures as a slide projection because you have no option for correction here; unlike digital editing or analog enlargement, where you can still iron out small flaws.
Kodachrome
We also want to mention what is possibly the most legendary slide film of all time: Kodachrome, which Kodak made from 1939 to 2009. Kodachrome was the first commercially available slide film with natural color representation. Its fine grain, ability to reproduce vivid colors, and archival longevity made it the film of choice for many professional photographers.
Unlike other reversal film processed via the E6 process, Kodak used its proprietary K-14 method for Kodachrome. In contrast to the C-41 process, K-14 was more demanding in terms of chemicals and machinery (the original K-14 processor required floor space of over 1,000 square feet), this film could not be developed in the local lab around the corner. It had to be sent to Kodak or a special lab for processing.
Black-and-White Slides
Black-and-white slides, produced from black-and-white negative film, are becoming more and more rare. The procedure for processing this type of film is considerably more complicated than normal film processing.
For Fomapan 100 R film, a reversal kit for reversal processing is still available. On the German website www.schwarzweissdia.de, Klaus Wehner offers reversal processing for Fomapan R with a process he developed himself. It allegedly achieves a considerably greater density range. In addition to Fomapan 100 R, there is also the black-and-white slide film Agfa Scala, which can be either processed using its own Scala process or one of the other two processes mentioned above. Sadly, the reversal kit for Kodak TMax 100 is no longer available.
5.2.3Other Types of Film
In addition to the normal versions of negative and positive film, there are also a few oddballs and special treatments with which you can turn normal film into something special.
Redscale
Depending on the exposure, redscale film creates results in surprisingly deep reds and oranges. You don’t even need special film for it, because redscale film is just normal color negative film that has been wound in reverse so it’s exposed from the back. Color film consists of several color, filter, and correction layers. When exposing it from the back, the color and filter layers are exposed in reverse order, producing the corresponding effect. You can buy redscale film ready-made or simply wind color film in reverse yourself in the changing bag.
Cross Processing
Color negative film (process C-41) and slide film (process E6) are almost identical, apart from the red mask of the color film. The reversal—turning the negative into a positive—happens as an additional chemical step during processing. Since both types of film are structured almost identically, you can also cross process them, i.e., process the slide film in the C-41 chemistry intended for color negative film and the color negative film in the E6 process.
Slide film works particularly well and can be enlarged just like a normal negative after the C-41 process. The results are very interesting, depending on film and exposure, and can produce high color saturation, strong contrasts, rough grain, and strong color shifts. If you hand in slide film to be cross processed in the drugstore, please write clearly “C-41 Process Please!” onto the film pouch—perhaps even directly onto the film cartridge with a waterproof pen.
Some labs charge extra for cross processing. You do not usually have to pay extra if you are using slide film sold as C-41 and designed specifically for cross processing, such as Rollei Crossbird.
Go ahead and play around with overexposing and underexposing when cross processing. Some types of film shift from predominantly red tones to green tones with different exposures.
Wind tunnel in Berlin Adlershof, Rollei Crossbird
Chromogenic Film Cross Processing
Chromogenic film is black-and-white film that is developed in the C-41 process designed for color negatives. This film can be processed in any color photo lab anywhere in the world that uses the normal color process. That makes processing much shorter and simpler. Plus, chromogenic black-and-white film has a very high exposure latitude, just like color film. Incorrect exposures are rare.
These advantages are offset by the disadvantage of standardization: The entire creative potential of black-and-white processing with its many different developers, temperatures, and times, and the resulting possibilities regarding contrasts and grain, is now eliminated.
Special Film
Color Negative Film
Special Film
5.3Instant Film
With instant film, we distinguish between two types: peel-apart and integral film.
Different packs of instant film (some are no longer available)
Peel-apart Film
Peel-apart film is mostly used in large format photography. The film consists of two parts: the negative and the positive. The exposed image is pulled out of the film back after the exposure. While you pull it out, two steel rollers squish a paste with developer chemicals between the two parts of the film, and the processing begins. After a processing time of a few seconds to several minutes, you peel apart the two halves to get your photo. Peel-apart film is only produced by Fuji today, though New55 is currently trying to get a new peel-apart film onto the market via a crowd-funding campaign.
Polaroid is the integral film most of us probably remember best. This film contains everything needed for instant pictures. In addition to the picture, the film cartridge comes with a battery that provides power for the camera. The Polaroid film integrates everything that’s needed for the picture. You do not have to peel anything apart or dispose of any negatives. After the exposure, a motor in the camera ejects the picture forwards and processing starts automatically. After a few minutes, you have a fully developed photo.
Polaroid SX-70 uses integral film
Polaroid Spirit 600 CL with Impossible PX600 Silver Shade, First Flush
Polaroid Spirit 600 CL with Impossible PX600 Silver Shade, First Flush
You often see people shake a Polaroid picture after shooting. That’s not necessary at all. On the contrary: the movement can even have a negative impact on the processing. Instead, you should keep the picture still (a dark coat pocket is best) until the processing is complete.
After Polaroid declared bankruptcy in 2008 and announced that integral film would no longer be produced, “The Impossible Project” was founded to continue producing instant film. They purchased the last Polaroid production site in the Netherlands and have been producing various types of film for the different Polaroid cameras since then.
Fuji Instax
Under the brand name Instax, Fujifilm offers not just digital photo printers but also two types of integral analog instant film that, like Polaroid film, contain everything you need for the picture. The film is suitable for the corresponding Fuji Instax cameras.
5.4ISO—The Film Speed
The ISO number on the film packaging (the nominal film speed) is a guideline on how to set the exposure meter so the film gets the optimal amount of light. If the film box says ISO 400, set the exposure meter to ISO 400, and all will be well.
But you can do much more. Exposing the film should not be seen as completely independent from the subsequent processing. Take a quick look at the “Massive Dev Chart” online database, which is a source for processing recipes (see page 152). As an example, let’s look at a common combination of film and developer: Kodak Tri-X 400 and Kodak HC-110. Instead of just one recipe for processing, the Massive Dev Chart will offer a long list of dilutions, processing times, and temperatures. This list includes ISO 200, 250, 320, 400, 800, 1600, 2400, 3200 and 6400.
If you have only ever dealt with digital photography, this may astonish you. Why should you change the exposure of the film? After all, there is no little wheel to adjust the film speed. The secret lies in processing. If we expose Tri-X at ISO 1600 instead of its nominal speed of ISO 400 (in other words, we give it 2 stops less light by setting the exposure meter accordingly), then we can process it later with the corresponding recipe to get a useful result. This is referred to as push processing. We could just as well expose the film for ISO 200 instead of ISO 400, giving it twice as much light. This type of compensation is referred to as pull processing.
So why do the film manufacturers bother specifying film speeds at all? In an ideal case, these film speed numbers mean that the film shows the biggest possible contrast range at the corresponding exposure. More important is the creative potential hidden within this information.
Push/Pull
Changing the exposure and using various ways of processing causes different results. Push processing increases the contrast; pull processing increases the film’s contrast range. Night shots that have been pushed over several aperture stops tend to show deep blacks and a strongly increased contrast. But you need to expose very precisely. The contrast range of a pull processing, on the other hand, can sometimes be so big that exposure errors are hardly possible.