What is Aperture?
The first of the exposure triangle we are going to learn is Aperture. Aperture by definition is a hole or opening in the lens, that allows light to pass through. The wider the hole the more light comes in and the more narrow the hole the less light gets through. Do you remember back to lesson 1 when we were talking about the window curtain? This is where that comes into play. Remember, that when we want to let in just a little bit of light, we only open the curtain just a tiny bit. When we want to let in a lot of light we open the curtain more. The same with aperture, the only difference is it’s a tiny hole that lets the light into your sensor. Here is an example.
One thing that can be confusing to some is what we call an f-stop. An f-stop ranges from f1.8 all the way up to f32 depending on the lens. Now here’s the confusing part, f1.8 is the WIDEST aperture or the widest opening of the lens, and f32 is the most NARROW opening of the lens. Crazy right? So to keep us from getting too confused we are going to stick with wide and narrow instead of big and small.
Aperture is not just used for letting in light, it’s also how we obtain depth of field. The depth of field is how much of your photo is in focus. Shooting wide open at f1.8 lets in the most light and gives you a small depth of field, also referred to as shallow depth of field. This means that whatever you focus on will be sharp but most everything behind it will be blurry. The more narrow the aperture is the more depth of field you will have, which means more stuff in your photo will be in focus. Take a look at these examples below. These are my son’s minions, I lined them up and took pictures at different apertures so you could see what is in focus and what isn’t.
You see how the more narrow the f-stop the more of the minions you can see?
Now, not all lenses can get as wide as f1.8. For example, the 18-55mm kit lens only goes to f3.5-5.6 depending on the focal length. It can be expensive to get a lens that opens up to f1.8 because it takes a lot of glass to make that lens. But there are so many benefits to shooting wide open. You can take a beautiful portrait of someone where the background has this beautiful blur. This can make for a gorgeous photo. But it also causes such shallow depth of field that one eye may be in focus but the other isn’t Just like Santa below. 🙂
Aperture is usually the first thing that you want to consider when you’re adjusting your settings. How much depth of the field do you want? This will determine what your aperture will be. Next, you will choose your shutter speed.
But that is lesson 3.
Tonight what I want you to do is get your camera out and find out how to set your aperture. Once you figure that out, I want you to take some pictures with different apertures so you can see the difference. If you can’t figure out how to set your aperture on your particular camera, just google the camera type and it should tell you.
I hope this lesson was helpful! Stay tuned for Lesson 3: Shutter speed.