What is pushing or pulling a film?

As a film photographer, you might hear or read the terms “pushing” or “pulling” a film. The concept can sound confusing but it’s actually very simple. Let’s break it down.

Every film comes with a “box speed” ISO rating. This is the speed at which you should shoot the film in order to achieve the best results.

Pushing film is when you shoot the film at a higher rating than its “correct” box speed. e.g. at ISO 800 instead of a box speed of 400. When you push film you are giving the film less light than it needs while your shutter reacts faster, allowing you to keep shooting with your camera handheld. Essentially you are underexposing the film. But you make up for this by altering the development time. This allows you to bring back the details you would have lost from underexposure.

Pushing film requires a longer development time than normal. If you’re getting your film developed at a lab simply tell them how you’d like your film pushed / pulled (e.g pushed +1 stop.) They will adjust the development time accordingly.

Film is pushed (and pulled) in stops. Pushing one stop means doubling the speed of the film. So a 400 ISO film pushed by one stop (+1) would then be rated at 800 ISO. Pushed by two stops (+2) means it would be rated at 1600. Logically then, a 400 ISO film pulled by one stop (-1) would be rated at 200 ISO.

As you have probably guessed, pulling film is simply the opposite of pushing. When pulling film you give the film a lower rating (e.g. ISO 200 instead of box speed 400.) This will overexpose your film as you are giving it more light than necessary, though on a shorter period of time. Again you compensate for this by developing it for a shorter amount of time.

Remember, if you only alter the speed at which you rate the film, all you are doing is overexposing or underexposing. The real pushing and pulling magic comes during development.

But why push or pull film?

The main reason why you might want to push or pull film is that you find yourself in a situation where the film you have at hand is not appropriate for the light. If you’re in a low light situation and the only film you have is ISO 400 then you may want to rate it at 800 or 1600 ISO in order to still be able to take some pictures.

The opposite problem of too much light does not normally pose the same issues. This is because most color negative and B&W film handles overexposure very well so there is little harm in the film receiving too much light. For this reason pulling film is not as common a practice as pushing film, however it may help decrease contrasts and bring more information in the shadows.

Some photographers also like the unique look that can only be achieved by pushing or pulling film. Pushing film typically results in higher contrast and more grain, while pulling film will significantly reduce contrast in the final images. It is a common practice to push B&W film, but it’s much more unusual to do so with color negative film because of the increase in color saturation. However both B&W and color negative film can be pushed and pulled with excellent results.

Experiment with this technique and see which effects are best for you!