One of the beautiful things about film is it allows for all types of experimentation, and one of the most common ways to manipulate film is by pushing it.
To a film newbie, the concept of pushing film is very foreign, since there’s no digital equivalent. I want to give a rundown on it without being too complicated or technical.
If you still have questions after reading this, please drop them below!
What it Means to Rate Film
Before I can talk about pushing film, I have to touch on rating film. (Trust me!)
Every film is labeled with an ISO (a light sensitivity) determined by the manufacturer. The ISO labeled on the roll of film is the ISO setting the film manufacturers intended you to set on your camera or light meter.
For example, Kodak Portra 400 (find on Amazon) is designed to be shot at ISO 400.
The term “rating” is just another way to say how you set the ISO on your camera or external light meter. If you set your ISO to 200, you are rating the film at 200.
The term “box speed” means to rate the film at the ISO listed on the film box or roll. Rating Portra 400 at box speed is setting your ISO to 400 (just like it says on the box!).
Rating Film Differently Than Box Speed
But many times, you’ll want to shoot your film at a different ISO than intended.
This means if I’m shooting a roll of Portra 400, I may want to set the ISO to 200 (telling my camera the film is less light sensitive than it actually is), which will overexpose the film by one stop.
If I set the ISO on my camera or light meter to 200, then I’ve rated my film at 200.
Why Would You Rate Film Differently Than What the Box Tells You?
Some films are notoriously light hungry (ahem…Fuji 400h), so people will set the ISO at 200 or even 100 when they’re shooting to allow for lots of overexposure.
Personally, I tend to rate Fujis at half box speed to overexpose them, and I rate my Kodaks at box speed (except Portra 800, which I also rate at half box).
When I’m shooting on an overcast day or I’m losing light or I’m shooting indoors, I need a faster shutter speed to capture moving kiddos.
In this instance, I might rate my film higher than the suggested ISO on the box so my shutter speed can get a little faster to capture the action.
But when I rate the film above box speed, it means I’m underexposing my film, and film doesn’t like underexposure.
Film gets its information by the amount of light hitting the negative, and if little or no light hits it, that part of the film will have little to no information on it.
Fortunately, there is a way to salvage these purposefully underexposed rolls of film via pushing the film during the development process.
*Note: I would be remiss to not acknowledge what setting a camera’s ISO does and doesn’t do.
The ONLY point of setting a camera’s ISO is for use of an internal light meter. Cameras that don’t have an internal light meter also don’t have an ISO setting.
I’ve heard panicking photographers who use their external light meter say that they forgot to change the ISO on the camera. If you solely use an external light meter, it doesn’t even matter what the ISO on the camera is set at.
*Double Note: Some people use the terms “pushing” and “pulling” for how they rate their film as well.
As matter of personal preference, I ONLY refer to pushing and pulling as the development process and stick to the term “rating” for how I set my meter’s ISO.
I find it far too confusing to not distinguish between what’s happening in-camera vs. what’s happening in the development process because as you’ll see below these things are completely independent.
Pushing Film vs Pulling Film
Pushing film during development means that the film sits in the developer longer than if it was processed under normal conditions. It is effectively allowing the film to “cook” longer.
So what happens when film is pushed in developing? When film is pushed, contrast is increased, saturation is increased, grain is increased, and color shifts can occur.
Pulling film is effectively the opposite. It’s allowing the film to spend less time in the developer thereby lessening its contrast and muting its colors.
This is typically not done with c41 film (color film) since it already sits in chemicals for such a short time, but some people will do this with black and white film, especially black and white film with high ISOs.
I will report back when I take the leap and pull some film.
Why Would You Want to Push Film?
People push film anytime they want to add contrast, grain, or color to their rolls.
Leaving film in the developer longer than normal allows any bit of the negative that has information (basically meaning it has some sort of exposure that hit it) to “cook” for a longer period of time, which can be especially helpful when purposefully underexposing film. It will in some ways compensate for underexposure.
Classically, if you rate your 400 speed film at 800 (thereby underexposing it one stop when shooting), you’d then compensate by pushing the film one stop in development.
This DOES NOT mean your film will look as if it was rated at 400. What pushing WILL do is salvage your underexposed film by keeping it in the developer longer but it will also give your film more contrast and grain than if it was shot at 400 and developed normally.
Regarding ISO, full stop differences are either half or double. So, if I take my 400 speed film and rate it at 1600, that means I’ve underexposed my film by two stops.
400 doubled is 800 (one stop), and doubled again is 1600 (two stops). Typically, that means I would push my film two stops in development.
Similarly, some people like to rate Ektar 100 at 400 (doubling the ISO twice) and push two in development.
This makes an already saturated film even more saturated and constrasty; when done well (read: good light and knowledgeable photographer), it’s gorgeous.
If you want to pull your film, you might take something like Ilford Delta 3200 and rate it at 1600 (overexposing it one stop since half of 3200 is 1600) and pull it one stop in development. But once again, I’ve never done this…..yet.
But this is film and the beauty is that we don’t have to follow the rules.
If you’re like me and you LOVE punchy color, contrast, and grain, then push your film just because you like the look of it.
So experiment! Rate your 400 speed film at 400 and push one in development just to add grain and contrast.
Or one of my favorites lately has been to rate my Tri-X 400 at 1250 and push two in development. It gives me that beautiful black and white grain but doesn’t add gobs of contrast that pushing 2 stops normally adds.
How to Develop Pushed Film
Sending it to a Lab
No matter how you rate your film, the most important piece of information for your lab is to know how many stops you want to push your film.
I always have a Sharpie handy to label my rolls so I don’t forget how many stops I want to push it. The lab needs this same information.
Want to push a roll one stop? Put a “+1” on the roll itself and then make a note on your order form.
Self-Developing Pushed Film
If you’re self-developing, know that pushing film is no more complicated than developing it normally; the film will just sit in the developer longer. All other steps remain the same.
All C41 is developed for the same length of time and that time is determined by the chemicals you use.
When you get your kit, the manufacturer should indicate how much extra time is needed per stop. You can check out my step-by-step tutorial for developing color film at home here.
When developing black and white film, use Massive Dev Chart. It is a completely comprehensive guide to times for pushing different films using various chemicals. It takes the guesswork out of developing and pushing black and white film.