Pushing and Pulling a How-to-Guide
Pushing and Pulling film is a technique in which you rate a film stock higher or lower than the recommended speed on the box and then change the development time of the film accordingly to combat the change. The box speed is always shown as the ISO or ASA and shows the temperature the film should be kept at for best results. In the example image below, the box speeds are shown as ISO 125/22, ISO 400/27 and EL 800. Most film speeds are easily identified in the name and brand like Cinestill's 800T.
When pushing or pulling, we usually talk in terms of stops which is how much more or less light we'll be exposing the film. For example, if you want to shoot a roll of Ilford Delta 3200 as a lower speed film for sharper landscape images, we could rate the film as 400 or 800. For 800 we would be a pulling the film down 2 stops.
To work out how much a stop is when we are pulling the film, we start by halving the box speed ISO. 3200 decreased by 1 stop would be 1600, and decreasing by another stop again would result in the film now being rated at 800 ISO. This means that you would have pulled your roll of Delta 3200 film to 800.
For pushing, this is similar but goes in the opposite direction - to add a stop we double the starting value, e.g 200 ISO > 400 ISO> 800 ISO equals 2 stops.
When and why you would Push or Pull film.
Pushing or Pulling film is done for a few reasons. The first and most important is available light. When loading your film you have a chance to decide based on the conditions you will be shooting in whether or not to expose the film to more light or less light. For example, if you know you'll be shooting at a concert and it'll be quite dark, you can push the film to expose for more light. Likewise, the opposite goes for if you are shooting on a very sunny day with a high speed film and you want a lower speed to use slower shutter speeds.
The second reason we push or pull is for film grain. Generally when pushing film, we gain more grain - the film is developed for longer and it is pushed to a level that it is not completely designed for. Pushing results in usually more contrast and less sharpness as the grain becomes enlarged. On the other hand, when pulling film, we get less grain which results in sharper images but slightly flatter photographs as the film is developed for less time, meaning the time for contrast and shadows to form is reduced. Pulling higher speed films (decreasing the ISO) is especially useful if you are doing portraits. A 400 ISO speed film like portra can result in sharper images when pulled, giving you a portra 160 like look and feel.
Reasons to Push
Dark interiors with less light and low shutter speeds.
Wanting more grain to achieve a gritty feel with your images.
Wanting a darker and more contrasty image with richer blacks.
Reasons to Pull
There is plenty of light available and we want to use slower shutter speeds.
- To have less grain with more sharpness, especially useful for portraits and landscapes.
Wanting flatter images or when shadows are strong and you'd like more detail in the shadows
When taking your photos and what to remember!
So you are planning on pushing your film! The number one thing to remember when pushing or pulling your film is the ISO, always set your ISO or ASA on your camera to the value of your push. If you don't have a setting on your camera that you can change to remind you of the ISO, write the new ISO on a piece of paper and stick it to the back of your camera as a reminder.
In the example image below, we are working with less light so we will be increasing our film speed for FP4 from 125 to 200. After setting the speed on your camera, you will need to set any external light meters that you are using to 200 as well. This will mean that every shot you take with your roll will be exposed for 200 and will be consistent with one more stop of light. Now you can go out and shoot!
Telling your lab!
When you have pushed or pulled your rolls, always tell your photolab. This will allow us to accurately develop your rolls for the speed that you have pushed or pulled to. On the film you can mark this with either a +1,+2,+3 or +4 and -1, -2 stops with a sharpie. We also have a section on our order form under Custom Processing, where you can include the +/- value, just make sure you also highlight the roll in your parcel.