What is film?

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What is Film?

Now this next bit may seem a little obvious, but the first generation of people who may never have seen a film camera are now coming to the age where they are surfing the internet and possibly encountering the mysteries of a film camera for the first time. So what is film? In this day and age it is simply a length of polyester based plastic covered with a silver derived photosensitive coating, that is - it reacts to light striking it (in the past the backing has been celluloid or glass). Now the science behind this would fill an entire website with ease, so we won't be covering this in any depth, search for "silver halides" in your favourite browser. For our purposes we will say that the films used today are very reactive to light and should never be exposed to light except inside the camera, again obvious to the film generation users, but we are a dying breed. Film allowed to come into contact with light outside of a camera will be exposed, ruining it, a condition known as fogging. For this reason film makers developed two principle strategies to allow the user to reload the camera with film in daylight without fogging the film. These are, a paper backing rolled with the film with an excess "leader" before the actual photosensitive film starts, or a small metal canister where the film exits through a slit with tight lightproof felt edges.

Aside from these principle mechanical packaging differences, there are different types of film available, ranging from black and white, or colour negative film, where the film is a intermediate stage - the final image being printed onto paper. Then there is colour transparency (or reversal) film, also known as slide film, viewed by holding to the light or projecting onto a screen. After this there are more technical films such as Infra Red and x-ray sensitive films, which for our purposes are outside the scope of this site. Within all these different film types are different degrees of sensitivity, indicated by the films' ASA rating, the higher the number - the more sensitive the film. A good 'everyday' film is Kodak Gold, 200 ASA, which we use as a standard in all museum 35mm cameras. As a film user you can choose to develop your films yourself or send to a laboratory. Different types of film require different processing treatment, a brief UK guide to methods used by The Living Image below, serve to illustrate the easiest solutions.

Film type	Makers	Brief Explanation	Format	Processors
Black and White	Various, Ilford, Kodak	A film that results in a transparent monotone negative image, normally used to produce a black and white paper print	35mm, 120 roll film & Sheet	Home processing, a worthwhile pursuit that makes you consider the image making process as a whole.
Colour Negative	Various Kodak etc.	A film that results in a transparent negative colour image, used to produce a colour paper print	35mm, 120 roll film	Laboratory C41 Process, we now use AG-photographic
Colour transparency	Fuji, Kodak	A film that results in a positive transparency used for projections	35mm, 120 roll film, sheet	Laboratory E6 process. Getting progressively more difficult now, Fuji still offer a process paid service in Europe, but Kodak have given up. Professional labs will still do E6 in all three formats.

Sadly a good number of the older film formats are now extinct, this makes using our old vintage cameras a bit of a challenge in some cases. However there are still many that can still be used with easily available film, so lets have a look at the film that is still relatively simple to get hold of. The numeric majority of vintage cameras will use one of these films types.

35mm Film

120 roll film