Pushing film is a technique that lets you extend the characteristics of a film stock to shoot in low-light conditions. The idea is simple: you deliberately underexpose your film in-camera and then compensate for it by overdeveloping the roll.
What Does “Pushing Film” Mean?
When developing black-and-white film, every film and developer combination has a specific development time. This time changes depending on the ISO at which the film was exposed.
If you shoot a roll at box speed, it means you exposed it at the ISO recommended by the manufacturer and printed on the film packaging.
Film speed (ISO) measures how sensitive a film is to light:
Higher ISO → more sensitivity to light, more grain.
Lower ISO → less sensitivity, finer grain.
Underexposing and Development
By setting a higher ISO on your camera than the film’s box speed, you are telling the camera that the film is more sensitive than it actually is. As a result, the camera gives less light to each frame—this is underexposure.
To compensate for this lack of light, the film must be overdeveloped. Increasing development time helps recover detail in both highlights and shadows.
Important: you can underexpose a few frames or an entire roll. However, if you plan to push film, you must underexpose the whole roll consistently.
Setting ISO on Film Cameras
When loading film, the camera needs to know the film’s ISO. This can happen in two ways:
1. Manually, using an ISO dial;
2. Automatically, by reading the DX (ISO) code on the film canister.
Many modern cameras allow you to override the ISO manually. However, some cameras—especially point-and-shoot models—do not.
Cracking the ISO Code
Most point-and-shoot cameras automatically read the DX code and set the exposure accordingly, without allowing manual control. This makes pushing film difficult—unless you alter the DX code yourself.
By physically modifying the DX code on the film canister, you can trick the camera into thinking you are using a higher-ISO film.
Example:
Ilford HP5 Plus is rated at ISO 400. By editing the DX code to ISO 1600, the camera will expose the film as if it were two stops more sensitive. This means each frame receives less light, effectively underexposing the film by two stops.
This technique allows you to:
- shoot in lower light;
- use faster shutter speeds;
- stop down the aperture for greater depth of field.
At the Lab
When submitting your film for development, always indicate the ISO at which the roll was exposed or how many stops it was pushed. The lab will adjust the development time accordingly.
Choosing the Right Film
Analog photography requires intentional decisions at every step. Choosing the right film involves balancing sensitivity, grain, contrast, and overall image quality.
Bonus tip: some films handle pushing better than others. We particularly like Ilford HP5 Plus when pushed—it gains contrast while maintaining a pleasing balance between highlights and shadows.
While color negative films can be pushed, doing so often increases contrast and causes color shifts. For this reason, we recommend pushing black-and-white films rather than color negatives.