The Basics of Film and Proper Exposures
MARCH 2023 ● ARTICLES
Properly exposing your film is one of the most crucial aspects of photography. Overexposure or underexposure can result in poor image quality and can ruin the vibes you want to capture. It can also make it harder to save your images through editing when you underexpose a frame. But we're here to help! Beyond nailing the "correct" exposure, having background knowledge can enable you to alter exposures to achieve a specific result or look in your image. When you depress that shutter button to snap an image, you're allowing light into your camera to hit your film. Before we dive in and throw out some tips, just remember that practice will be your best friend; as you shoot more, you will naturally progress and gain valuable experience. It can also be helpful to bring a little notepad to jot down your camera settings while snapping away. Once you get your negatives and scans, you can review those notes and make changes for future rolls. Most importantly, don't get discouraged; try new techniques, and have fun! It may sound corny, but when you "screw up" an exposure, don't view it as a "failure." Try to frame the experience more positively, and you'll be headed in the right direction.
First, beginners should try to grasp three main components: aperture, shutter speed, and ISO/ASA (film speed). These elements work together to expose your film. Changing one of these components individually will affect the other two. For example, let's say your camera settings are set to the correct exposure for a given scene. If you change your shutter speed and nothing else, the image will no longer be properly exposed. In this case, you'll also need to change your aperture. You may be wondering how to know when to change your aperture and shutter speed and the reasoning. We'll get there! But for now, you just need to understand that these three components are the main ingredients for cooking up a correct exposure.
Take advantage of a light meter. Some cameras may have built-in light meters (you'll want to test the accuracy, though, as some film cameras can be quite old). You can also buy prism finder attachments for some cameras. With prism finders, you may even have the option of using either spot metering or average metering, which can help you expose for a specific element in your photograph, like the shadows, or you can expose for the overall light in the image. Or, you can buy handheld light meters to read and measure the light in a scene, which will help determine a set of correct exposures. There are even smartphone apps that can get the job done. And yes, several combinations of the three main components can produce a proper exposure. Let's say you're shooting 400-speed film during the day to give you an example. Depending on your surroundings, clouds, etc., a correct exposure could mean using a shutter speed of 1/1000th of a second and an aperture of f/2.8, 1/250th of a second and an aperture of f/5.6, 1/60th of a second and an aperture of f/16, and so on. Bright sunlight, or environments with lots of snow, for example, will generally require a faster shutter speed and a smaller/more narrow aperture. Apertures are "smaller" the higher the f-stop number is. For example, f/32 would be a very small or narrow aperture. Low light conditions will generally require a slower shutter speed and a larger aperture.
To reiterate, determining the correct exposure to match the available light in a scene is a practice in balancing your aperture and shutter speed for a certain ISO. The aperture controls the amount of light that enters the camera through your lens. Shutter speed refers to the amount of time your film is exposed to light. ISO is the film's sensitivity to light.
Bracketing your shots may not be super cost-effective, but it can also help you, especially as a beginner. Or, if you find yourself in an amazing situation where you just can't stomach the thought of incorrectly exposing, you can employ this strategy. Bracketing is the process of taking several shots of the same scene but at different exposures. With each shot, you use varying settings for your aperture and shutter speed. This can help ensure that at least one of your shots will come out how you like.
Tripods can also be tremendous tools for helping you to achieve a proper exposure. Say you need to use a slow shutter speed but don't want to risk your image appearing blurry. Using a tripod can keep the camera steady. Tripods (and shutter release cables, which screw into the top of your shutter button) are also great for shooting at night; they open up the set of exposure settings you can play with without having to risk a blurry final product. Say you want to get car headlights that span the whole width of your image. You'll need to do a long exposure and keep the shutter open for several seconds as the car passes through your entire frame. Once you know how long you want to keep your shutter open or what shutter speed you'll be using, you can use your light meter to tell you the corresponding aperture setting for a correct exposure based on that film's ISO rating. But, reciprocity failure can become an issue. Don't worry, though; we'll also touch on that later.
Before moving on, let's briefly revisit some of the terms and components.
Aperture refers to the size of the opening in the lens through which light enters the camera. It is measured in f-stops, which represent the ratio of the focal length of the lends to the diameter of the aperture. Lager or wider apertures, defined by lower f-stop numbers such as f/1.4, allow more light to enter the camera. Larger apertures also result in a more shallow depth of field, which creates a blurred background and helps to isolate a subject. Smaller apertures let in less light, resulting in a greater depth of field. Larger apertures are perfect for when you want everything in the frame to be in focus, commonly with landscape photography, for example.
Shutter speed refers to the amount of time the camera shutter remains open and the amount of time the film is exposed to light. Shutter speed is measured in seconds or fractions of a second. A faster shutter speed, say 1/1000th of a second, will freeze the action in a scene and prevent motion blur. Faster shutter speeds can also be great for bright settings, as you can risk letting too much light into your camera. Slower shutter speeds, like 1/30th of a second, for example, allow for more light and can create motion blur. If you want to avoid blur, you will need to practice having a steady hand and possibly breathing techniques or mount your camera on a tripod. Be careful, though, as you can risk overexposing your film if the shutter is left open for too long.
ISO refers to the film's sensitivity to light. High ISO films, say 800 speed, are more light-sensitive, allowing for faster shutter speeds and/or smaller apertures in low light conditions. However, higher ISO films are more prone to producing more grain. But that can be a stylistic choice. Low ISO films, say 100 speed, are perfect for well-lit environments. Films with lower ISO ratings generally produce finer grain and cleaner grain structures.
Let's talk about grain!
When someone mentions grain in film photography, they are referring to the texture or granularity in a photograph. What is film emulsion? It is the light-sensitive coating that is applied to the surface of film and is made up of materials that contain silver halide crystals. When the film, or emulsion, is exposed to light, a chemical reaction creates a latent image. Developing the film allows that latent image to become visible on the film. So, grain is the random distribution of silver halide crystals in the film emulsion. Many photographers are drawn to film because of the aesthetic that grain creates.
Your exposure can significantly impact the grain present in your images. Overexposing your film can result in blown-out highlights and loss of detail, increasing the perception of grain. On the other hand, underexposing your film can result in dark shadows, increasing the contrast between the grain and the image, which in turn also makes the grain more noticeable.
As we discussed earlier, ISO plays a role in the amount of grain present in your images. Grain characteristics will vary by film. Choose wisely for your setting and the overall look and mood you want to capture! When an image is exposed correctly, you'll tend to have less noticeable grain and more even tonal range. But, it is all up to you, the artist. Do you want the aesthetic element of grain to be more pronounced in your images? Do you want cleaner, finer-grain structures? Do you want to expose for the shadows in your scene to grab that detail but risk blowing out the highlights? It's all your choice, and up to you to find the right balance. It takes time, though, to find that balance and hit your stride in developing your style and producing images you love.
Let's move on to tonal range!
In film photography, tonal range refers to the degree of brightness values that can be captured by a specific film, from the darkest shadows to the brightest highlights. For example, Kodak Portra 400 will have a different tonal range than Fujicolor 200. Each film's tonal range is determined by the emulsion's sensitivity to light and how it handles varying brightness levels. Films with wider tonal ranges can capture more detail in both shadows and highlights, giving a more balanced and dynamic range. This can be an important factor, especially when shooting in high-contrast environments with a more pronounced difference between a scene's brightest and darkest parts. The development process and the chemicals used during processing can also affect the tonal range.
Now, let's discuss latitude and color profiles!
Latitude refers to a film's ability to capture a range of tones and colors. Sensitivity to light and tonal range play a role in evaluating a film's latitude. Remember when we mentioned the concept of "saving" an improperly exposed image? This is much more easily done with films that have great latitude. Let's take Kodak Portra 400 again, for example. This film has great latitude and can be scanned/edited with a broader range of desirable results for a given exposure. Imagine you exposed for the shadows in a scene to get the details there, but it resulted in blown-out highlights. When scanning your negatives or editing your shots in Lightroom or Photoshop, you have way more room to "save" the highlights and bring back that balance between the darkest and brightest portions of your image without introducing other issues. Films with more forgiving latitude are also perfect for those who like to scan and edit their pictures in a specific fashion to achieve a particular look. When shooting a film with poor latitude, you have less of an ability to edit your images and less room for error when initially setting your exposure. Wider latitudes allow you to capture a broader range of tones and colors. Film latitude can also vary, of course, depending on the film's color profile and the development process.
Color-negative films (processed C-41) generally have wider latitude than slide films (processed E-6). When shooting slide film, achieving a correct exposure is much more crucial, even if you don't plan on scanning your own film or editing the scans from your lab. Slide films generally produce images with higher contrast and more vibrant colors. Color-negative films are great for softer tones. Experimenting with different films is an absolute blast and is a great way to learn about photography while finding your style.
Finally, let's get to reciprocity failure!
Remember when we discussed long exposures and introduced the term "reciprocity failure?" This phenomenon occurs when the relationship between exposure time and a film's sensitivity to light breaks down. This typically affects films with ISO ratings of 400 or slower and becomes more of an issue the longer you keep your shutter open. Higher-speed films tend to have fewer issues with reciprocity failure. Imagine you want to capture those cars and get all of the trails left by their lights throughout the entirety of your frame. Or maybe you want to capture the stars in a remote location on a clear night. You set your shutter speed and meter for the scene using the film's ISO and then naturally adjust for the corresponding aperture. If your exposure is too long, the basics begin to break down; your image will not be properly exposed.
As we mentioned earlier, when a film is exposed to light, the light and its energy are absorbed by the silver halide crystals in the emulsion. Of course, the longer you expose your film, the more light the crystals absorb. But at a certain point, the crystals become saturated, and the film's sensitivity decreases. This will lead to underexposed images, color shifts, loss of detail, and an increase in grain.
So, how do we circumvent this problem? We must compensate for reciprocity failure and correct our exposure times, straying from the basics and usual rules for achieving a perfect exposure under normal conditions. You will need to use an app or tool that can apply the film's reciprocity correction factor to achieve the correct exposure for that scene. You can usually find this information for each film online or through the manufacturer. Neutral-density lens filters can also reduce the amount of light entering your camera during long exposures.
That's a wrap!
Now that you've been introduced to the basics, we think you'll have a hell of a time getting out and capturing some killer images. By practicing the art of balancing the right combination of aperture and shutter speed based on your film's ISO rating, you'll be able to unleash your creativity and create stunning images that match your visions. Taking the time to study, learn, and practice the fundamentals of film photography will make a world of difference. But again, this must be done through experience and can be a process of trial and error. So, grab your camera, experiment with different films and settings, be patient, don't be afraid to make mistakes, and channel your inner artist. Happy shooting!