How to Improve Your Photography With the Exposure Triangle
Exposure is one of the most important concepts in digital photography. That means it's also one of the first things an aspiring photographer should learn. But if you're like me, you might find it difficult to find the right settings for your camera to get your shots to look just right. That's where the exposure triangle comes in.
What Is The Exposure Triangle?
The exposure triangle is basically a simple way of understanding how your camera captures light in a photograph. It's made up of three separate, yet interrelated components:
- Shutter Speed
Each of these components influences the amount of light that ends up in the final image, but they also affect other aspects of the image as well. That's why it's important to consider your creative goals for the photo, and then set each of these settings in the order of importance.
What Should My Shutter Speed Be?
When your camera captures an image, the shutter opens to allow light to enter, then it closes. Your shutter speed determines how much time passes between the opening and closing. Shutter speed is usually measured in a fraction of a second such as 1/40 or 1/15.
Now, the longer the shutter is open, the more light enters the camera, the brighter the exposure will be. As an example, here are a few photos I took using different shutter speeds.
Notice how the longer shutter speeds result in brighter images. But we can't rely on this alone to determine our exposure. When objects are moving, longer shutter speeds result in a phenomenon known as motion blur.
Notice how the longer shutter speed has resulted in not only a brighter image, but more motion blur as well. Sometimes you can use this for artistic effect, such as when photographing flowing water. But other times you might want there to be very little blue, such as when taking a picture of a hummingbird, whose wings would blur at long shutter speeds.
In this example, the shutter speed was high enough to create a blur just from the movement of the camera. When taking long exposure photographs, it's important to keep the camera as still as possible to avoid this.
So what shutter speed should you use? It depends on what you're photographing, and whether or not you care about motion blur. If this is a priority for you, set the shutter speed first, then worry about the other two settings.
What Should My Aperture Setting Be?
Like shutter speed, aperture size affects the amount of light entering your camera. If a camera were an eyeball, the aperture would be the pupil, which can expand or contract to control the amount of light that enters it.
Now, things would be very simple if that were all the aperture did. You could could just set your shutter speed based on the amount of motion blur you wanted, then adjust your aperture to compensate, and BAM, instant masterpiece.
But it's not quite that simple. There's another property that is affected by your camera's aperture, and that is known as Depth of Field. Essentially, DOF determines how blurry the "out of focus" elements in an image become. When your aperture is wide open, you get a very shallow depth of field. When your aperture is smaller, your DOF gets very wide.
Here are a couple of examples.
The first image was taken with the aperture as wide open as I could get. The second was taken with a much smaller aperture. Notice that the first image has a very blurry background, while the background in the second image is more focused. This is one artistic aspect of the photograph that you have to consider when deciding aperture size.
How Do We Measure Aperture Size?
Your aperture size is represented by a number known as f-stop, which will be written like F4.0 or F5.6. This number depends on certain factors, such as what lens you're using, but here's the general rule.
The higher the F-number, the smaller the aperture and the wider the focal area. The smaller the F-number, the larger the aperture and the more shallow the focal area. Small aperture means less light, large aperture means more light.
It may seem counterintuitive at first to have a larger number mean a smaller aperture, but just think of F-stop as being how much light is "stopped" from entering the camera. Larger numbers mean more light is "stopped."
What Should My ISO Be?
There's one final piece of the digital exposure puzzles: ISO.
ISO stands for International Organization of Standardization, which doesn't really help you understand what it does. Basically, it refers to light-sensitivity of the image sensor in your camera. A larger ISO number means your image sensor is going to be more sensitive to light. Conversely, a smaller ISO means less light sensitivity.
But as always, it isn't that simple. If it were, you could simply set your shutter speed and aperture size based on your artistic preference, and then set the ISO to adjust the final exposure of the image. And BAM! Instant masterpiece!
This is going to depend on your specific camera, but generally speaking, higher ISO numbers mean a brighter, but potentially grainier image. That's because at very high ISOs your camera is going to try to pick up more light than is actually available. This results in digital noise in the shadows of the image.
Here are some examples.
Notice that the second image is considerably grainier than the first, especially in the shadows (but it actually isn't too bad, since I used a flat color profile for all the photos). The first image used a low ISO, and the second used a high ISO.
You'll have to get a feel for this based on your specific camera, but as a general rule, lower ISO results in a less-noisy image.
Time To Put It All Together
Now that we know how the three points of the exposure triangle work, it's time to put them together. When taking a picture, you have to decide which of these aspects is most important to you:
- Cleaner or noisier image?
- Shallow or wide DOF?
- High or low amounts of motion blur?
I usually start by adjusting the ISO to be as low as possible. Having a clean image is most important to me. Then I adjust the shutter speed and aperture based on my artistic preference. Finally, if the image is too bright, I apply an ND (neutral density) filter to further limit the light entering the lens.
If the image is too dark instead, I simply add more lights to the scene. Of course, this is only possible in situations where I have that kind of control. If you're taking photos outside of a studio-like setting, you might have to just use the light at your disposal. Outdoor, daytime photography often has enough light. But if you're shooting at night, you might just have to get creative with your exposure settings.
There are other factors that can affect your exposure triangle, such as your choice of lens, and even your choice of camera. But remember that these are general guidelines. Your personal creativity should be the driving factor in your photography, so don't be afraid to break the rules every now and then!