Photography Tutorial: Aperture

In this lesson, you will learn what aperture is and how it affects exposure. Aperture is the first part of the exposure triangle and the first part of your camera, that controls how much light enters and is captured. Inside your lens is a hole, this hole can go bigger and smaller and this is the aperture which is sometimes called the iris, similar to the iris of the pupil of your eye. Now, if you make the aperture larger, do you think more light is let in or less light? that one is easy, more light is let in when the hole is bigger, this means that increasing the size of your aperture, will make your image brighter, decreasing will make it darker. So when you are in a darker location like shooting inside a building, you might want to increase the size of your aperture to expose properly. Think about what happens to your eye when you turn off the lights, your pupil gets really big to let in more light. so that you can see when you go outside, in the bright sun, your pupil will get smaller to let in less light. So depending on your situation, you can have a perfectly exposed image with different aperture sizes. How do we adjust our aperture? and f-stop? Also known as the f-number, is a method of describing the size of the aperture in each lens. This f-stop scale goes from F1 to F1.4 to F2 to F2.8, to F4 and beyond. There are two potentially confusing things about this f-stop scale though. First, the smaller the F number, the larger the aperture, by subversive the larger the F number, the smaller the aperture. So when F 2.8 is actually a larger aperture and lets in more light than an f11 does that make sense? The other confusing thing is that not all lenses are made equally. It takes a lot of expensive engineering to make an aperture that opens up really wide to something like an F1.4 or F2. So if you're using a kit lens the one that came with your camera, your aperture might not open to these wider F-numbers, similarly if you're using a mobile phone or a point-and-shoot camera, you might not have these f-number or f-stop options. Here we are outside, we've got our friend William here, who is going to be playing a big part in this class and I'm using a basic Canon T5i DSLR, similar to the DSLR cameras that many of you might be using in this class. And now I'm going to show you how changing your aperture or your F-stop, will affect the exposure and with this kit lens which is the 18 to 55, that came with this camera, we can't even open up meaning increase our aperture wider than 5.6 F 5.6 with this lens zoomed in like so. So here I'm at 5.6 and I'm just going to go up to 6.3 7.1 8.0 and as you can see as I go up an f-stop, the aperture is actually getting smaller and letting in less light. So if I go all the way up to 22 or even beyond, it's completely underexposed and if I go the opposite way, we're opening up again, up to 10, F 9.0, you can see on the screen that the f-stop number is represented by 7.1, not a fraction of F over 6.3 and now we're up to 5.6 and we are generally exposed properly, but if we're still too dark, we have our other settings to get perfect exposure. How do you adjust the aperture on your camera? This will depend on the camera you're using, and we suggest checking out the camera anatomy section of this course, where we will provide resources on how to use all of the popular brands and models of cameras. Typically there's a dial on your camera body or a button to press and toggle, which can change your aperture setting. So now let's put this all into practice. In a real-world situation, If I'm taking photos of Sam here and I want to be able to expose properly using my aperture, here's how I would do that. Right now my aperture is set to 2.8 and it's really, really bright, so, if I take that shot, it is overexposed and I would make Sam smile perhaps. So what I'm gonna do is actually close down my aperture. I'm out of f 2.8, now I'm going to go down to something like F 5.0, look here Sam, smile. So that's how just with the aperture you can fix your exposure. Of course this is all just one part of the exposure triangle, my shutter speed and ISO settings will also affect the exposure and we'll get into those in the next two videos. Following that, we'll see how we balance all of these settings to get a perfectly exposed shot. Now I know this lesson is getting a little long, but I want to talk about one other thing with aperture. Your aperture also affects other things like depth of field which we'll cover more in depth in the depth of field section of this course, very briefly though the depth of field is how much is in focus what plane of your vision is in focus. Is the entire scene in front of you in focus? from three feet in front to 100 feet? or is just a sliver in focus? perhaps what is five to six feet in front of you is in focus, but everything beyond that is really blurry. So how does aperture or your f-stop affect this? A wide open aperture has a shallower depth of field meaning a smaller sliver of your scene is in focus a smaller aperture has a deeper depth of field. So if you're shooting a wide open landscape and you want everything in focus, you'll want to close down your aperture, making it smaller. If you're shooting a portrait and you want a blurry background, open up your aperture, make it wider. And just a reminder if you are opening up your aperture, you're actually making your f-stop number smaller, if you are closing down your aperture, you're making your f-stop number bigger. This shallow depth of field is one of the things that can make a not-so-great photo look more professional. But remember not all cameras and not all lenses can open up to very wide apertures. So depending on your equipment, this may or may not be possible. Here I have a new lens on this camera, it's the 50 millimeter that opens up to an F 1.8. I'm gonna snap the shot, so you can tell with an F 1.8, the background is very, very blurry so to contrast that I'm going to close down the aperture all the way to 22 and then to expose I'm gonna adjust the shutter speed which we'll get into in more detail in the next lesson. Ok, I'm gonna take the shot. So now when we review these two photos, you can see that the one that was shot with the f-22 aperture, everything behind William is still InFocus, the depth of field is very deep, it's 5 or 6 feet behind him and it's still InFocus compared to the F 1.8 shot where everything behind William is very, very out-of-focus. By now I hope you understand what aperture is and how it affects exposure. For now, go out and practice changing your aperture setting to see how it changes your exposure and your depth of field and next we're going to dive into shutter speed.