Join Ben Long for an in-depth discussion in this video What is exposure?, part of Photography Foundations: Exposure (2010).
When you are shooting, it is very easy to focus all of your attention on your subject, and how you want to frame it. After all, your subject is what makes your photo, right? Only partly. People often ask me, what do you like to shoot? For a while this question really confused me, until I realized that the answer for me is light. I like to shoot nice light. It doesn't even necessarily matter what that light is bouncing off of. Light creates texture. Light and shadow together can create a sense of depth in your scene, or allow you to control the viewer's eye, and controlling the viewer's eye is the essence of composition.
There is no photography without light, and the secret to controlling light is to understand exposure. Even if you are not well-versed in the history of photography, you have probably seen a lot of movies. Think about the strong shadows in a great film noire movie--so named because the images had lots of war or black in them. Or think of the rich colors and the dramatic lighting as the hero rides off into the sunset in the classic western. These are all moods and atmospheres that are created through lighting and exposure.
Movies are a photographic process, after all, and cinematographers have to know the same exposure theory that we photographers do. So what exactly is exposure? Let's go outside for a minute. You have probably experienced this. Ah! You step outside, and it's too bright until your eyes adjust. Now you probably also experienced this. I step into a dark room, and I can't see anything until my eyes adjust. That's exposure.
The pupil in my eyes, the black part, is an iris that can open and close to let in more or less light. That takes a certain amount of light for me to be able to see. So when I am in a dark room, my pupils are opened very wide to let in enough light for me to see. When I stepped outside, my pupils were still opened very wide, so wide that I couldn't see, because my vision was overexposed. All I could see was white. Now, when that happens to you, you may not think of it as seeing white, probably because you are more focused on the pain as the nerves in your eyes gets overloaded.
But to sum up, when I am in one situation, my eyes need a particular setting. When I take those same eyes into a very different lighting situation, that setting is no longer correct, and I can't see. That may sound familiar to you, not just because you have eyes, but because that's how your camera works. It needs different exposure settings, depending on how bright or dark the light in your scene is. Like your eye, inside your camera's lens there is an iris, or aperture, that can be opened or closed to let in more or less light. But your camera has an additional mechanism for controlling light, in the form of a shutter.
It's a little curtain that can be opened and closed quickly or slowly to let in more or less light. And that's all exposure is, controlling the amount of light that gets to the image sensor in your camera. Too much light, and your image will be overexposed. It will be too bright. Highlight details will be lost to complete white. Colors will be washed out. Too little light, and your image will be underexposed. It will be too dark. Shadow details will be lost to complete black. Tone and color will be dull and dingy. Now, you might be wondering why your camera has two mechanisms for controlling light when your eye can get away with just one.
The answer to that is complicated, and we will explore it in detail throughout this course. Right now, know that the practical upshot of having two controls in your camera, and the reason that you want to learn more about them, is that they provide you a tremendous creative possibilities. So we learn exposure theory not just to ensure that our images are neither too bright nor too dark, but to expand the creative palette that we have at our disposal when we are shooting. We are going to be learning a lot of numbers, and concepts, and terms in this course, but in the end your eye and your lens are both optical devices, so a lot of what we are going to learn is going to feel familiar to you, because you already have a lot of experience with a pair of lenses and apertures that you use every single day.
- What is exposure?
- Exploring camera modes
- Light metering
- Shooting sharp images
- Controlling shutter speed
- Understanding f-stops
- Controlling motion
- Working with a shallow depth of field
- Measuring aperture
- Shooting in low light conditions
- Performing manual light balance
- Working with the histogram
- Using fill flash
- Understanding reciprocity