This post is part of the Better Family Photography series.
If you are ever planning on getting off of autofocus and composing your own shots (and you should!) then you need to know about the exposure triangle. As the name implies, it is made up of three components. The exposure triangle is what determines how much light is let into the camera when you take your photo, and shapes how your photo will look. First let us take a look at the three elements individually so we understand how they work before you add them all together.
Aperture or f-stop
This is the size of the opening of the hole inside the lens. This controls how much light is let in. The smaller the number, the more light you let in. The larger the number, the less light you let in. For example, if you use an f-stop or aperture of 16, there will not be as much light let in as if you use an f-stop of 5. Remember, the lower the f-stop is, the bigger the hole is and more light that is let into your camera. Lower f-stops are very important for low light situations. However, the lower the f-stop, the less of your shot will actually be in focus. If you want everything to be in focus, you can use a larger f-stop, like 12. Automatic focus uses a large f-stop so everything is in focus. If you only want a tiny part of your photo to be in focus, use a lower f-stop, like 3 or 4. This is where artistic vision comes in.
Using a lower f-stop also lets in a tremendous amount of light, which can create beautiful contrast in your photos.
The next thing to think about is your exposure timing. This has to do with the amount of time your shutter is left open. The longer it is left open, the more time light has to enter into your camera. But when you leave your shutter speed open longer, you are also allowing for more time to pass and when time passes, things move. This movement creates blurring. By changing your shutter speed you can stop time in an instant, or capture the passage water takes as it falls over the edge of a cliff. Shutter speeds range from 1/1000 of a second to 1 second and even longer for long exposures. When you are photographing children, you generally need to have a shorter shutter speed because kids move around a lot. I recommend using at least 1/50 of a second, if not faster.
This number indicates a particular film’s sensitivity to light. But in the digital photography age, you can change your ISO setting because you are using digital film (if you will). You want to use lower ISO settings like 100 to 200 in settings where you have a lot of direct sunlight, and lower ISO settings indoors and outside in the shade, like 600 to 800. In night shots you might want to go as high as 2000. This might seem like a magical exposure fairy, to adjust to any situation, but there is something you need to remember about shooting with high ISO numbers. The higher the ISO number is, the more grainy your final photo will be. High ISO numbers equal more “noise” which is the photographic term for what looks like little dots all over the place. I personally do not like noise in my photos, so I use the lowest ISO number possible depending on the situation.
So now that you understand each individual member of the triangle, you need to think about how they come together to create an ideal exposure. The three different members act as if playing a tug of war in order to keep your exposure balanced. For example, if you want to use a higher f-stop, which lets in less light through a smaller hole, you need to use a slower shutter speed or a higher ISO. If you want to use a lower ISO you need to compensate by using a slower shutter speed and lower f-stop. If you want to use a fast shutter speed because you do not want motion blur, you need to use a higher ISO and lower f-stop number. This might sound extremely intimidating, but all you need to do is practice. Go sit in a room with your camera and instruction book, figure out how to change the three different settings, and practice, practice, practice. There are also handy charts that help you know which ISO to use in different situations like this one.
And make your life easier, download this free light meter app for your iPhone/iTouch to help you get a basic idea of your setting options.
Happy travels (and travel photos!!)