What is Film For?
Portable cameras were in use in the eighteenth century which projected an image onto a piece of paper so that you could draw round it. It wasn't long before people got lazy! They started to wonder whether the camera could draw the picture for itself.
The first book of photographs, produced by Fox Talbot, was called "The Pencil of Nature". Nature, it seems was still being thought of as an artist. The photographs for the book were printed in Reading, at Fox Talbot's establishment in Baker Street.
So, we use film because it is easier, and quicker, than learning to draw!
Common Types of Film
Colour Negative Film
Most of the film sold in this country produces colour prints. This is the kind of film which is used to take holiday snaps (and, incidentally, most press photographs; the black and white pictures you see in your daily paper are often made from colour negatives!).
The name of this kind of film usually contains the word "color" (for example, Kodacolor and Fujicolor). This is a "negative film". This means that once the film has been processed, it must be printed before recognisable pictures are produced. Typical colour negatives have an overall orange colour. The advantage of this two stage process is that the second stage, printing, can be repeated many times. Many prints can be produced from the same negative.
Colour Transparency Film
The next most popular film produces colour transparencies. It is sometimes called "reversal film". The name of this kind of film usually contains the word "chrome" (for example, Kodachrome and Ektachrome). This is a "positive" film. This means that once the film has been processed there are recognisable pictures. There are no negatives. The film which was in the camera is cut up, the individual pictures mounted in plastic or card frames and loaded into a projector to be shown.
Prints can be made from transparencies; many of the colour prints shown in camera club competitions are made from transparencies. However, if you asked a photographic laboratory to produce several prints from a transparency, they would start by photographing the transparency using negative film. They would then make the prints from the negative. This kind of negative is called an "internegative".
Black and White Film
So much for colour, what about black and white? The same distinctions apply; there is "negative" black and white film and there is "positive" black and white film. The black and white prints which you see in club competitions are produced from black and white negative film.
There is only one commercially available black and white positive film. This comes from Agfa and is called Dia-Direct.
Less Common Types of Film
There are many kinds of film many of which have only specialist applications. There are a few, however, which you may come across.
Infra Red Film
"Infra Red" film which produces a black and white image from a form of light which the human eye cannot detect. The result is to produce distortions of the expected tones. Green leaves come out white while blue skies appear black. Overall the effect is like a ghost landscape.
The film has more serious applications than simply to produce distorted tones. It has medical applications; some skin complaints show up more clearly when photographed using infra-red film. Since infra-red cannot be seen by the unaided eye, it can be used to take photographs of wild animals at night without the animals being disturbed.
Tungsten Balanced Film
If you use ordinary colour film indoors using artificial light, the resulting picture will have a yellow cast. This is, not surprisingly, because the light is yellow! We don't normally notice this because our brains compensate for it. Film has no brain so it can't compensate.
Tungsten balanced film produces a slightly blue image to counter the yellow produced by artificial light.
Slide Copying Film
If you try to copy a transparency using ordinary film, the result will have increased contrast. This is OK if that is the effect required... However, normally what is wanted is an accurate copy.
Slide copying film produces an especially low contrast image in order to produce a copy closer to the original.
Polaroid
Polaroid film has been around for many years now. Sometimes called "instant film", it can be processed quickly outside a darkroom. Indeed, in some cases the film can develop itself!
There is a range of 35mm films produced in this form. These cannot develop themselves, but come with a separate chemical pack which must be used in conjunction with a special developing tank. Both "black and white" and "colour transparency" films are available.
One consequence of the process used to produce these colour transparencies is that they are darker than conventional transparencies. If they are projected alongside conventional transparencies they will look underexposed.
Lith Film
This is an extremely high contrast black and white negative film.
Formats
You can't use any kind of film if you can't fit it into the camera! Not all types of film are made to fit all types of camera. You would find it difficult, for example, to fit sheet film into a 35mm SLR. Sheet film doesn't come rolled up, it comes packed flat in boxes. The sheets can come in many sizes, but the commonest is probably 4 x 5 inches.
The commonest film sizes are:
| Film | Image Size | Common Name |
| 135 | 24mm x 36mm | (35mm) |
| 120 | 50mm x 50mm | (2¼ square) |
| 126 | 28mm x 28mm | (Instamatic) |
| 110 | 13mm x 17mm | (one-ten) |
"135" is the 35mm film used by most amateurs. (The name 35mm comes from the width of the film including perforations.) "120" is the roll film which fits those slightly larger cameras such as the Hasselblad and the Rolleiflex. Most types of film are available in "135" and "120" formats.
The "126" and "110" formats are used in cheaper "point and shoot" cameras. The film is loaded into a cartridge which doesn't need to be wound back before being unloaded. Only a few film types are available as instamatic cartridges.
The Writing on the Box
If you buy a box of film there will be various numbers written on it, not all of which seem to make any kind of sense. It is not possible to be exhaustive here, but here are a few pointers.
On the end of the box will be a code something like "135-36". The first number tells you the film size; in this case 35mm, the second number is the number of exposures.
Somewhere on the box will be something like "ISO 100/21°". This is the film speed. In this example, 100 is film speed in the old American ASA form, while 21 is the same film speed in the equally old German DIN form.
Most camera light meters use the ASA form.
The film box will also give an indication about the processing required. There are three codes to watch out for. C-41 is the standard processing required for colour negatives. E-6 is the standard processing required for most colour transparencies. The exception is Kodachrome which uses K-14.
Finally don't forget that every film box has a "process by" date stamped on it. If you are buying from an unknown chemist who had to blow the dust of his stock in order to find the film, check this date very carefully.
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