Photographic Film has a long and interesting history. We invite you to journey back in time with us as we take a look at the milestone developments in this exciting medium over the last 180 years.Light, Colour, Action!
It all started when the daguerreotype was introduced in 1839. This was the earliest practical photographic process and did not use film. Light-sensitive chemicals were formed on the surface of a silver-plated copper sheet.
The first photographic film was pioneered by George Eastman, founder of Eastman Kodak, in 1885 and the first version was a coating on a paper base. The image-bearing layer was stripped from the paper and attached to a hardened clear gelatin. In 1889 the first plastic roll film was manufactured. It was called “nitride film” and it was made from highly flammable nitrocellulose (“celluloid”).George Eastman
In 1908 Kodak introduced the first safety film or “cellulose acetate film”. This film was an alternative to the hazardous nitrate film and was cheaper, tougher and slightly more transparent than the nitride film. Safety film was used for 16mm and 8mm movies, while nitride film remained the standard for 35mm theatrical film. The nitride film was finally discontinued in 1951 when it was also replaced by safety film.
Photographic film as we know it today, is a strip of a transparent plastic film base, coated on one side with a gelatin emulsion containing microscopically small, light-sensitive silver halide crystals. The characteristics and size of the crystals determine the contrast and resolution of the film.
The black-and-white photographic film only has one layer of silver halide crystals, while the colour film has a minimum of three sensitive layers which incorporate different combinations of sensitising dyes. Normally a blue-sensitive layer is on top, followed by a yellow filter layer to stop any remaining blue light from affecting the layers below. Then a green-and-blue sensitive layer, followed by a red-and-blue sensitive layer. The last two record the green and red images respectively.
There are mainly two types of photographic film:
- When developed, Print Film yields transparent negatives with the light and dark areas. When using colour film, the respective complementary colours get inverted.
- Colour Reversal Film. This process produces positive transparencies and is also known as slides. If mounted in cardboard, metal or plastic frames it can be viewed with a slide projector or slide viewer. Alternatively, it can be viewed with a loupe or on a light box.
The most significant event in the history of film was probably when George Eastman developed the Box Brownie Camera in July 1888. The camera came loaded with a 100 exposure film. When the roll was full, the camera together with the film was sent back to the factory in Rochester, New York, where it was printed. It was then reloaded and sent back to the customer. The genius of Eastman’s business model was not the product, but his marketing strategy. He made photography accessible to millions of amateurs with no particular professional training. His advertising campaign was effective and simple: “You take the picture, we do the rest best!”
The Speed of Light A roll of 400 speed Kodak 35mm film.
Film speed rates a film's sensitivity to light. The International Standards Organization (ISO) scale is the international standard for rating film speed and combines both the ASA speed and the DIN speed in the format ASA/DIN. Using ISO convention film with an ASA speed of 400 would be labelled 400/27°.
The most common film speeds are ISO 25, 50, 64, 100, 160, 200, 400, 800, 1600, 3200, and 6400. Most consumer print films are in the region of ISO 100 to ISO 800. The higher the speed, the higher the F/stop can open given the available light. Also, the higher the ISO, the grainier the picture gets. ISO 25 is very slow film, as it requires much more exposure to produce a usable image than "fast" ISO 800 film. Films of ISO 800 and greater are therefore better suited for sports photography where the short exposure time limits the total light received and for low-light.
The slower film speed has the benefit of having a fine grain that has better colour rendition and saturation than fast film. Professional photographers of static subjects, such as portraits or landscapes, usually seek a fine grain ISO. It requires a tripod to stabilise the camera for a longer exposure.
Special films Polaroid camera with picture being processed
- A very good example of a special film is a Polaroid or instant film. The camera takes the picture, and the photo immediately comes out of the camera. The film consists of a special type of chemistry that automates and integrates development, without the need of further equipment or chemicals.
- X-ray film is commonly used in the medical profession. A subject gets placed between the film and a source of X-rays, without a lens, as if a translucent object were imaged by being placed between a light source and standard film. X-ray film has a sensitive emulsion on both sides of the carrier material that reduces the X-ray exposure for an acceptable image – a desirable feature in medical radiography.
- DX Encoding (Digital Index), or DX coding was developed by Kodak in the 1980’s but was later used by all film and camera manufacturers. The DX Encoding provides information on both the film cassette and on the film regarding the type of film, speed (ISO/ASA rating) of the film as well as the number of exposures.