Exposing and metering negative film is important, although not hard as slide film. If you’re coming from digital photography, you’ll see that you have to change how you expose your shots. What is recoverable in post-editing in digital cannot be recoverable in film and the opposite as well. In this post, I’ll first very briefly explain how digital and film register light for you to understand why their metering should be different. Afterward, I’ll then tell you how we should meter and expose negative film. I’ll talk about reversal film (slides) in another future post.
Before starting let me give you a cool analogy to make you start thinking. Negative film is to film photography as RAW photos are to digital photography. But how we edit one is the opposite of the other. Let’s see why.
How a Digital Sensor Records Light
There are millions of pixels on a digital camera sensor. Each pixel has a small cavity that is uncovered when we press the shutter button and measures how much light is hitting it. With that information, the camera then measures the intensity to give to each pixel and saves it into a RAW and JPEG file.
Let’s say that we’re editing a photograph in RAW format. If we want to lift up the shadows, we can do it, a lot. Why? Because the sensor still captured light. That light, that information, can then easily be amplified. However, if not properly exposed, we can’t recover all of the highlights! They keep being white, even if we reduce the exposure several stops. Why does this happen? It’s because each cavity in the sensor can only record light until reaching a certain amount of maximum light. From then on, the sensor loses all the excess light that it can register. We cannot recover it. So, we have to be very careful about properly exposing the highlights and then lift the shadows in post-editing. This is why there is a maximum of expose for the highlights.
How Negative Film Records Light
Film cameras are essentially black boxes to which we attach a lens and can put film inside. Film is made of a chemical emulsion scattered over one side of a plastic. This chemical emulsion is basically made of tiny silver crystals that are light sensitive. Each film’s sensitivity/speed depends on how large and sensitive those tiny silver crystals are.
When we press the shutter button, the mirror flips out of the way (if it’s an SLR) and the shutter curtains open. That is when the light enters the camera through the lens and hits the film. After shooting an entire roll of film, then it’s developing time. The crystals that were sufficiently excited stay on the film and the others that weren’t are washed away. All the areas where each photo didn’t receive enough light are completely or almost entirely lost. These start to be noticeable right when you are one -to two stops underexposed. While the areas that received a lot of light still retained information. Even if they were exposed 6+ stops above, which shows how much exposure latitude film has. This is why it’s almost always better to overexpose your film photos.
If we grab a developed film, we see that the photographs are actually negatives. The highlights are (or should be) almost black and the deep shadows are transparent. This blackness and transparency is often referred to as thickness. Almost black, full of emulsion negatives are well or overexposed photos and these are called thick negatives. While almost transparent negatives are underexposed photos and are called thin negatives.
Exposing and Metering Negative Film
Having said this, how should we expose and meter film? Well, it depends on the look you want to achieve. However, for general good results you really should overexpose what you get from your camera meter. Why? Because of how film works and how it retains highlight information so well! This will minimize grain in black and white and color negative film. It will also result in better colors in the shadow areas for color negative film.
And how should you do it? You can do it in two ways:
Expose for the Shadows
It’s simple and it’s what I personally do. Point your viewfinder/meter to the shadow areas of your subject/scene and meter it. Depending on how strong the contrast is, you will generally overexpose your photo by 1 or 2 stops. Don’t worry, your negative film will handle it and probably get better results. Actually, lots of photographers overexpose their color negative film by 1 or 2 stops.
Set a Slower Film Speed / Smaller ISO
It’s also simple. Reduce your camera film speed / ISO by one or two stops and just normally meter and shoot. For instance, if you’re shooting Portra 400 just set your camera’s film speed to 100 or 200 instead of at 400. This way you don’t have to meter for the shadows and recompose. You only have to meter your scene normally and shoot, without recomposing.
Do you want to see examples of how a scene differs if you overexpose and underexpose it? Please do check this excellent blog post from Carmencita Film Lab that already did this experiment.
Do The Opposite of What I Just Said
Photography can still be art for us to express ourselves and have a unique look. And how can you do that? Shoot different themes that are relevant to you. And experiment with different ways to get a look that appeals to you. How? Do the opposite of what I just said to you. Actually, lots of photographers that really like the grainy, muddy and vintage look that you can get with underexposed film. And they’ll attract an audience that also enjoys that look.
Final Thoughts on Metering Negative Film
We’ve seen how film differs from digital sensors in how they record light. Film is light hungry, while digital sensors are light sensitive. We also saw that exposing and metering negative film is actually the opposite of what we already do for digital! You’re in doubt if your film metering is actually correct? Overexpose a stop, you don’t lose anything by doing that. Do you already do all of this and want to try something new? Then do the exact opposite. You might be surprised.