How-To: Push and Pull Photographic Film and Why

by Chuck Baker

Pushing and pulling film are techniques used in film photography to intentionally alter the effective sensitivity (ISO/ASA) of a film roll during shooting and compensate for this change during the development process. This allows for greater flexibility in challenging lighting conditions and can be used to achieve specific artistic effects.

1. Understanding Exposure and Film Speed (ISO/ASA):

  • ISO/ASA: This number indicates the film’s sensitivity to light. A lower ISO (e.g., 100) means the film is less sensitive and requires more light for proper exposure. A higher ISO (e.g., 400, 800) means the film is more sensitive and requires less light.
  • Exposure: Proper exposure is a balance between aperture, shutter speed, and ISO. Changing the ISO effectively alters the amount of light needed for a correctly exposed image.
  • Stops: Exposure changes are often measured in “stops.” One stop represents a doubling or halving of the amount of light. For example, going from ISO 400 to ISO 800 is a +1 stop change, requiring half the amount of light for a proper exposure. Going from ISO 400 to ISO 200 is a -1 stop change, requiring twice the amount of light for a proper exposure.

2. Pushing Film (Increasing Effective Sensitivity):

  • Shooting: To push film, you set your camera to a higher ISO than the film’s box speed.
    • +1 Stop Push: Set ISO to double the box speed (e.g., ISO 400 film shot at ISO 800).
    • +2 Stop Push: Set ISO to four times the box speed (e.g., ISO 400 film shot at ISO 1600).
    • And so on…
    • This intentional underexposure is done when you need a faster shutter speed in low light or a smaller aperture for greater depth of field than the film’s rated speed would allow.
  • Development: To compensate for the underexposure, the film needs to be overdeveloped. This means:
    • Longer Development Time: The film is left in the developer for an extended period. The exact time increase depends on the film, developer, and the number of stops pushed. Development charts, like those on the Massive Dev Chart or instructions provided by film and developer manufacturers, provide guidelines for adjusted times.
    • Potentially Higher Developer Temperature or Stronger Developer Concentration: In some cases, adjustments to temperature or developer dilution might also be recommended, but increased development time is the primary method.
  • Effects:
    • Increased Contrast: Highlights become denser faster than shadows during extended development, leading to higher contrast.
    • Increased Grain: The silver halide crystals in the emulsion are forced to develop more, making the grain more visible. The degree of grain increase depends on the film stock.
    • Increased Saturation (Color Negative): Colors may become more saturated, sometimes with color shifts.
    • Loss of Shadow Detail: Severely underexposed shadow areas may lack information and become very dark, even with extended development.
    • Brighter Overall Image: The overdevelopment compensates for the underexposure, resulting in a more usable negative or transparency.

3. Pulling Film (Decreasing Effective Sensitivity):

  • Shooting: To pull film, you set your camera to a lower ISO than the film’s box speed.
    • -1 Stop Pull: Set ISO to half the box speed (e.g., ISO 400 film shot at ISO 200).
    • -2 Stop Pull: Set ISO to one-quarter the box speed (e.g., ISO 400 film shot at ISO 100).
    • This intentional overexposure is done in very bright, high-contrast situations to retain highlight detail.
  • Development: To compensate for the overexposure, the film is underdeveloped. This means:
    • Shorter Development Time: The film is removed from the developer earlier than the standard time. Again, development charts provide guidance for reduced times.
    • Potentially Lower Developer Temperature or Weaker Developer Concentration: Similar to pushing, temperature or dilution adjustments might be suggested in some cases.
  • Effects:
    • Decreased Contrast: Highlights are prevented from becoming too dense during the shorter development, resulting in lower overall contrast. This helps retain detail in bright areas.
    • Finer Grain (Potentially): With less aggressive development, the grain structure may appear slightly finer.
    • Reduced Saturation (Color Negative): Colors may become less saturated and more muted.
    • Better Highlight Detail: The main benefit is the preservation of detail in bright areas that might otherwise be blown out.
    • Darker Overall Image: The underdevelopment compensates for the overexposure, resulting in a less dense negative or transparency.

4. Practical Considerations and Techniques:

  • Metering: Accurate metering is crucial. When pushing, metering for the mid-tones or slightly darker areas can help retain some shadow detail. When pulling in high-contrast scenes, metering for the highlights is often recommended to prevent them from overdeveloping.
  • Film Choice: When looking at quite a number of sources for B&W films that push and pull better than others, I realized that this is a matter of taste. Fomapan is loved by some and disliked by others. The same seems to be the case for just about any B&W film. I personally have found Kodak Tri-X and Fomapan 400 to push very well. Fomapan produces a grainier result. For Pulling film my experience has included Rollei RPX 100, Fomapan 100 and Rollei Infrared 400, again with success. However, success for me can easily mean failure for another photographer. Color negative films can also be pushed or pulled with varying results in terms of color shifting and grain. Slide film (E-6 process) has a much narrower latitude and is less forgiving to significant pushing or pulling often resulting in noticeable color shifts.
  • Whole Roll Commitment: Pushing or pulling must be decided before you start shooting a roll of film, as the entire roll will require the same altered development.
  • Marking Your Film: Clearly mark your film canister indicating that it has been pushed or pulled and by how many stops. This is essential for the lab if you’re not developing it yourself. Include this information on any lab processing forms.
  • Home Development: If developing at home, consult reliable development charts and be precise with your timing and temperature. Experimentation might be necessary to fine-tune your results with specific film and developer combinations. Keep detailed notes of your processes and outcomes.
  • Pushing/Pulling Limits: You may like the results of extreme pushing and pulling so take the limits of this technique for what it is worth. So here are the words of advice from some photographers: avoid extreme pushing or pulling (more than 2-3 stops) as the image quality can degrade significantly with excessive grain, contrast, and color shifts.
  • Creative vs. Corrective Use: While pushing is often used out of necessity in low light, both techniques can be used creatively to achieve a desired aesthetic.

In Conclusion:

Pushing and pulling film are valuable techniques for photographers to gain more control over their images. They allow for adaptation to challenging lighting situations and offer creative possibilities to alter the contrast, grain, and overall look of photographs. Understanding the effects of over and under development and carefully adjusting both shooting and development processes are key to achieving the desired results. Experimentation and meticulous record-keeping are highly recommended, especially when developing film at home.