In the Darkroom - Push Processing Your Film

Do you have some practical experience processing your own film? Want to go to the next level and have more control over your negative quality? Then push processing is your next step.

Push processing is exposing a particular film at a higher ISO than it is rated, and modifying development (usually time) to compensate. Push processing is generally done for one or more of four reasons:

1. A faster film is required

2. Pushed for effect (increase grain size)

3. Pushed for contrast (increased contrast)

4. Economy

Generally, the most widely used reason for pushing a film is to access a more light sensitive system. It can be used in an emergency - when fast film is not available - or to have the flexibility of using existing film stock to push to a desired ISO requirement.

It is generally cheaper to push slower film than to purchase very fast film (the faster the film the more expensive). It is conceivable to push a 400 ISO film to 6400 ISO (4 stops) and beyond. However, there are consequences to keep in mind when pushing film to these limits. The most obvious consequence when pushing film is an increase in grain size and change in contrast. These can be excessive and considerable testing is required to balance all these factors.

Pushing a 400 ISO film to 3200 or 6400 ISO gives you the ability to photograph under very low light conditions. This may be very useful for night photography or indoor photography where a flash is unavailable or not allowed.

In addition to push for speed, many photographers like to intentionally push for effect. The main characteristic change when pushing film is grain size. The further you push a film, the greater the grain size. This effect can produce huge grain size and is used widely for aesthetic reasons.

The other effect that can be obtained is to push for contrast. Increased contrast is another effect that some photographers use for aesthetic and/or quality reasons. A harder looking print may suit some genres better than a normal or soft contrast. This can be resolved by manipulating the development time.

A combination of push for grain and push for contrast may also be used. Two world renowned photographers who use this method are Ralph Gibson and Don McCullin. This results in a high contrast, large grain negative. Determining how much of each characteristic to be acquired for the image is to be resolved by the photographer and may take much experimentation.

Another reason for pushing is you simply made a mistake. The last film in your camera was 800 ISO and you just shot a new roll of 100 ISO at 800 ISO. The film is going to be 3 stops under exposed if you process normally. To resolve this you simply push process 3 stops, problem solved.

Push processing your negatives can take you into a new mysterious world of negative characteristics when you experiment with this method. As well as extending the development time for pushing, decreasing developer to water ratio and increasing temperature are two additional means to achieve the same result.