This is Part 2 in the series 3 Things to Know. We’re looking at how the camera adjusts to light.
The camera adjusts the amount of light in three ways. Last time we went over the first and easiest to understand – shutter speed. Why it’s important, what it does and how to use it.
Just to review: (You may remember this from last time, but it’s worth repeating.) The camera needs light to see things just like we do. Light bounces off an object into our eyes. The camera works the same way. The light bounces off an object and into the camera. Our eyes adjust to light. For example, our pupils become smaller or larger to let more or less light come into our eyes. The camera essentially does the same thing. It adjusts to the amount of light and can change to what it needs to see.
Let’s go over aperture.
Aperture is – how wide the lens opens up to let the light into the camera. It the opening that the light comes in is small, less light comes in. If the opening is big, more light comes in. Let’s say you’re in a room that’s pitch black. There’s a light on in the next room, but you can’t see that light in your room. Now, someone cracks open the door from that room into your room, just a little light comes in. Now they open the door all the way, a lot of light comes in. Now transfer the door opening into roundness. A small round hole – a little light. A big round hole a lot of light. That’s aperture.
Aperture numbers are given in f-stops. The f-stop is really a function of the lens and can range from around 1.4 to 24 or so. Some with bigger variations and some smaller. The confusing part of this is the numbers are opposite of what you think they should be. If we look at the mathematical formula they actually do make sense – don’t worry we’re not actually doing that.
The higher the aperture number, the smaller the opening. What?!? Yes. That’s right. Therefore, the lower the aperture number, the bigger the opening. So, if you have your aperture set to f/2.0 it lets in more light than if you have it set to f/5.6.
But wait, there’s more. Aperture also plays a part in depth of field. Depth of field is how deep the focus is. Stay with me and stop day dreaming. If the f-stop is high, let’s say f/16, almost everything in the picture will seem like it’s in focus. That’s a long or deep depth of field. If the f-stop is low, let’s say f/1.4, only what you focus on will be in focus. For example, you’re taking a photo of a person using f/1.4 and they’re turned ¾ toward you, not face on. With 1.4, if you focus on their closer eye, the other eye will be out of focus. That’s a shallow depth of field.
All the variations of f-stop are very useful, not only for how much light they let in, but how it effects depth of field.
The lens will have written on it the lowest f-stop it can go to. This is usually printed on the front of the lens. If it says 4.0 that means it can open to 4.0.
Depending on the camera you have, the aperture can be set on a camera dial, set-up menu in the camera settings, or on the lens itself.
The combination of aperture and shutter speed give you a lot of variety in terms of light gathering. Aperture is how much light comes into the camera and shutter speed is how long that light is coming in.