Photography 101: How to Understand Film Speeds
Posted on January 6, 2010
Filed Under Digital Camera Features, Good Digital Cameras |
Cameras have tons of little dials, knobs and meters. If you look long enough on a camera, you can find more ways to change how your photo look than you can count, and for most of us, more than we can process all at once. But did you know that one of the most important decisions you can make when taking pictures happens before you even load your film?
The speed of your film is one of the unchangeable qualities of a picture. There are plenty of ways to toy with aperture, exposure, and focus. However, once you select your film and load it into the camera, there is no way to change how the film reacts to light. In every picture you take with film, you’re adapting to the film speed. Film does not speed up or slow down to suit your needs, so it is important that you make the right call the next time you head out for a fresh roll.
ISO and You
The film speed measures how sensitive the film is to light. Low film speeds indicate that the film is less sensitive, and will require a longer exposure; high speeds are very sensitive and require shorter exposures. The speed of a film is commonly known as its ISO. Any film you buy will have its ISO marked on the box, and common speeds are 400, 800, and 1000, with 400 being the closest to the “standard.”
The ISO of your film affects every aspect of the way your camera works. Your light sensor (if you have one) has to be set correctly for the film you’re using, your aperture will be more or less limited depending, and your shutter speed will likely have to decrease or increase to accommodate the film. Even digital cameras have a simulated (and adjustable) film speed that they base their calculations on.
Choosing the Right Speed
The ISO of your film decides what you are capable of photographing, and how. Because high-speed film (ISO 800 or above is a good general rule) requires less time to expose, you can shoot images with much higher shutter speeds than with a slower film. The result will be a photo with crystal clear action; fast film is great for taking sports or anything with movement. When you see a photograph of a basketball player suspended in midair, you can bet that image was shot on high-speed film. With a slower ISO, the player in question would likely be a huge blur. Faster film also needs less light and can be super helpful in situations where a flash isn’t appropriate indoors.
Lower speed film captures more detail because it has more time to absorb light. It’s important to keep the words “detail” and “blurry” separate- more “detail” in a picture is similar to a high definition TV having more “detail” than a regular television- more of what was originally there will be seen in a photo. The longer film can “see” a scene, the better the scene will be represented. Lower speed films are great for images like portraits where you want to show great depth of field.
Film Speed Experiments
To get a good handle on how ISO works and what it does to your images, here are a couple of things to try out the next time you’re planning a shooting day:
- Get rid of your flash (if you have one) and take some fast film into a low light environment
- Swing by a local high school, college, or little league game and try shooting (with permission) two rolls of film – one very slow (ISO 100) and one very fast (ISO 1000) – then have a look at how different the images turned out
Film speed is one of those great things to play with when you’re pretty comfortable with your camera and you’re looking for new ways to challenge your perceptions. Each speed has its strengths and weaknesses so it’s up to you to decide which one works best for you. Now it’s time to take some pictures that you’ll be proud to hang on your wall!
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