Aperture
The question has come up. What is Aperture? I will not go into extreme detail, as most of my blog readers are beginner photographers who just want general information about taking better photos.
Aperture is the size of the hole behind the lens that lets light into your camera. See these two pictures to see what I’m talking about. The one on the left has a larger aperture (or hole) while the one on the right has a smaller aperture (hole). The camera determines the size of the aperture needed in order to obtain a perfect exposure based on the amount of light coming off the subject. The more light you have, the smaller the aperture you can have. This makes sense since smaller holes allow less light in.
Of course, the size of the aperture is only a third of the equation for perfect exposure, but we’ll get into shutter speed and ISO in a different post. For now, let’s think about aperture.
The question now is, why would you want the hole to be bigger or smaller? The answer lies in the creative aspects of depth of field. A camera turns a 3-dimensional view into a two-dimensional picture. Our eyes can look at a scene in front of us and instantaneously focus on many parts of the scene showing us how far away the mountains are in the background and how close the person is standing next to us. A camera can only take a photo of one depth, or one level of focus. Something will be in focus and others will not.
This is called depth of field. A very large depth of field means that many things in a photo are in focus, the background and the foreground. A small depth of field means that one part of the photo is in focus and nothing else. So, different aperture sizes allow the photographer to add a creative aspect to each photo choosing how much will be in focus. Very large apertures allow you to blur the background. This works wonderfully for portraits, flower shots, and photos where the background just doesn’t matter to the photo. Very small apertures allow you to keep both the background and the foreground in focus. This works best for landscape photos when you want the mountains to be in focus as well as the person standing in front of them. See these examples.
Tiny depth of field = Large aperture
Large depth of field = Small aperture
I focused on the bird’s eye. In the first photo with the large aperture, you can see that really only the eye is in focus. The feet (slightly in front of the eye) and the whole background (behind the eye) are blurred because of my large aperture setting. In each picture thereafter, I slowly closed the aperture a couple stops. Scroll through the pictures from top to bottom and notice how more and more stuffed animals come into focus until in the last picture you can see that everything is in focus with the tiny aperture. So, the size of the aperture controls the depth of field. The larger the aperture, the more blurry the background will be. The smaller the aperture, the more in focus the background will be.
Which picture is correct? They all are. They just portray a different creative viewpoint.
How do I set the aperture size on my camera?
Point and Shoot Cameras:
You don’t have very many options on your camera for controlling the aperture. However, most cameras have different shooting modes. The portrait mode will set the camera to the largest aperture that the lighting allows for. The landscape or scene mode will set the camera to the smallest aperture. Some cameras allow you to change the mode with a dial on the top of the camera, and others allow you to change the mode by a series of buttons on the back. Take a look at your camera and see what yours can do. Next time you take a picture, use one of these modes to get a more creative look at your subject. Use the portrait mode for portraits and flowers. Use the scene mode for landscapes.
DSLRs and cameras with a manual mode:
If your camera has an aperture-priority setting (usually depicted by an A on a settings dial) or is a DSLR, you are in luck. You have the ultimate creative control of your photos. Try shooting a few pictures in aperture-priority. What this allows you to do is set the aperture that you want for the most creative photo, and then the camera will determine what the shutter speed needs to be in order to obtain the correct exposure. (Note, that if you do this, be sure to watch the shutter speed. If it has to take pictures longer than 1/60 seconds, you better put your camera on a tripod.)
Since you can set your own aperture, I better give you a primer on f-stops. An f-stop is basically a measurement of how big your aperture opening is. Your camera might have f-stops of 2.8, 3.5, 4.5, 5.6, 8, 11, 16, and so forth with some numbers in between. They actually stand for 1/2.8, 1/3.5, and so on. Note that because f-stops are actually fractions, 1/2.8 (.36) is bigger than 1/22 (.05). Here’s where it gets confusing! f/2.8 is a larger aperture than f/22 because 1/2.8 is bigger than 1/22. This is very important to know because I said up above that a larger aperture blurs the background. An f-stop of 2.8 is a larger aperture than f/22, so f/2.8 will blur the background much more than an f-stop of 22 will.
You must be ready to scream at me. I don’t blame you. Remember this part of aperture was the hardest thing about photography for me. The only way I was able to remember was to remember that small numbers = blurry backgrounds and big numbers = large depths of field. Go back and look at those 5 photos above of the stuffed animals.
- Photo 1 was taken at f/1.4.
- Photo 2 at f/2.8.
- Photo 3 at f/5.0.
- Photo 4 at f/8.0.
- And Photo 5 at f/16.
Small numbers mean blurry backgrounds. You can also think of it like this. Small numbers = small depth of field. Large numbers = large depth of field. Small numbers are great for portraits and flowers while larger numbers are good for landscapes. Practice with it and soon you won’t be able to take a picture without first thinking of the depth of field or aperture.
As always, use the comments section of the blog to ask your own questions and I will dedicate a blog post to your question.
