To truly understand photography, you only need to understand a few basic principles. First and foremost is that photos are created by light. Traditionally it was light hitting film, but these days it’s mostly light hitting a digital sensor. The Greek root of the word “photography” literally means “writing with light”. So everything we are going over today will be dealing with how that light enters your camera. The amount of light entering your camera is referred to as exposure. Let in too much light and your picture will be too bright, or over-exposed. Don’t let in enough light and your picture will be too dark, or under-exposed.
The three things that determine how much light enters your camera are aperture, shutter speed, and ISO. These three things work together to let in the light and determine your exposure. Today (for the sake of your sanity!) we will just be focusing on aperture.
The aperture refers to the adjustable size of the hole in your camera that lets in the light. It is measured in f-stops. The smaller the f-stop number, the larger the opening. I’m a visual person, so it helps me learn if I can see a diagram!
Aperture is important because it determines your depth-of-field, or the portion of your photo that is in focus. A wide open aperture gives you a very shallow depth of field, so only a small portion of your photo will be in sharp focus, and everything in front or behind will be very blurry. A very small aperture will give you a much greater depth-of-field, so everything in your photo will be in focus, front to back. A good way to remember this: people squint (making their eye opening smaller) to see things in better focus, so therefore, you can remember that a smaller aperture gives you more of everything in focus from front to back.
Your own personal preference and artistic flair is what determines what aperture you should use! It totally depends on what you are trying to achieve with your photo. For instance, I love the beautiful blur in the first example! To me it looks more artistic, dramatic, and professional. But some people may opt for the second photo because you can clearly see all the details of the gorgeous dessert table! Like I said, it just depends on you and what you are trying to accomplish with your photo.
Here are some more examples:
In the first photo you can see that it is a very wide open aperture at f-1.2 and the depth of field is very shallow. Only one bottle is in focus and the ones directly in front of it and behind it are already starting to blur a little. And the farther in front or in back you get, the blurrier things become.
In the next photo, the aperture is a little more closed up at f-4.0 and more of the bottles are in focus. But the bottles at the ends are still blurry.
In the last photo, the aperture is even smaller at f-9.0 and all the bottles are clear and sharp. The depth of field is even getting great enough that you can start to see the wall in the background coming into focus a bit, which in the other two photos was so blurred that you couldn’t tell what it was.
On an SLR camera you can choose your own aperture for your photos, but keep in mind that certain lenses can only open so wide. Some have only a maximum aperture opening of f-2.8 or even f-4.0, so those lenses wouldn’t be able to open as wide as others that can go all the way to f-1.2 (like my favorite lens)! So if you like the look of a shallow depth-of-field, you’ll want to look for a lens that has a very low aperture number.
Although I prefer shooting completely in manual mode, an easier way to begin experimenting with your aperture setting is to use the AV mode (aperture priority mode) on your SLR camera dial. In AV mode you can determine your own aperture, and the camera will automatically determine your shutter speed and ISO for you!
So… what if you have a point and shoot camera but you still want to get some background blur in your pictures? The good news is that you can, at least to a certain extent. Just set your dial to “portrait” mode, which has an icon that looks like a person’s head. This setting will tell your camera to open its aperture as wide as it is able to. Awesome!
Next, I’ll be teaching you all about shutter speed and ISO!