Now the aperture controls how much light is coming through the lens. And the aperture is a really interesting one because it does some funny things to your image. Now as you can see in this image, just a very narrow aperture on the screen, that's probably about f 22. The smaller the aperture, the less light is coming in. So with the aperture, we control the amount of light that's coming in a wide aperture like f 1.4. And that would be the top of our stop chain if you remember.

That gives us a shallow depth of field, but a narrow aperture maybe like 45 not all lenses go that far. But let's say f 22. They're going to give a deep depth fulfilled now what is the depth of field? depth of field is how much of a field Hold is in focus. So let's imagine you had a really big field about this big. A shallow depth of field means the lens, you might focus on the middle of the field.

And the lens is going to have about this much of the field in focus. But if you have a narrow aperture, you'll get a deep depth of field and you'll get the whole field in focus. And that's a little bit mind bending, because you would think a big aperture would give a big depth of field, but it doesn't, it gives a narrow depth of field. There's mathematics all goes into this, but you don't need to understand that all you need to understand remember, wide aperture, shallow depth of field, and once you practice it clicks, you've actually just got to take the camera out, we've got some exercises for you later. And use these principles and you'll see how they work. And then the next gives a deep depth of field.

So let's have a look at some images. And think about them leavers again, and how that's going to affect the images we're going to take. If you look carefully at this image, you will see at the top of the image, there's some paperwork on the desk calendar, and it's blurry, you can't see the image. And if you look in the bottom of the image at the keyboard, you can't see the keys. But if you look at the hand, the hand is very sharp and in focus. And you can see the depth of field on this you can see where it starts to disappear.

So if you look at the keyboard, by the time you get to Zed and Q, the depth of field is disappearing, as some very handy tools you can get on your mobile phone called depth of field calculators, where you put all of your free lever settings in and it will tell you when you finish On the subject, how much your debt fulfilled will actually be. So in this image, we've shot this about f4 maybe even f 2.8 because there wasn't much light in the office and that's given me this shallow depth fulfill now it gets more extreme, you go down to 1.4 1.2 Now don't get too carried away really shallow depth fulfilled when people find this I want to go crazy in it take portraits on one eyes and focus and your eyes blurry. That's because of the depth of field. So a lens with a large aperture of 1.4.

That's more lighting because the holes bigger but it has this funny effect of creating a shallow depth of field, which is the opposite of what you might expect. Now in this image, if you look very carefully, the flowers in the foreground are in focus. And the mountains in the background are in focus. That is a very deep depth of field. So what's happened in this image is someone is got their camera put on a tripod. And I've took this image and they've set that lever, the problem at F 22. sort of took it down.

And I've still froze the motion in places. Now how have they managed to do that? Well, I must have adjusted some of the believers. They probably push the highest syrup a little bit, but they've definitely got a long exposure. Now, if it was a windy day, you have a long exposure to start getting problems. But what they've got here is a very deep depth of field and the way you control that is with the aperture to get to F 22.

And then a little tip for you about third of the way in, focus on something a third of the way into your image. And then what will happen is, everything in the back will be focused and everything on the front of will be focused. Most people would go to the middle of last not the way it works, just go a third of the way in. Now the wide aperture also creates what we call Bo k. Now, a lot of people pronounce it different ways. It comes from the Japanese word and nobody seems to be sure how to pronounce this covered it called bouquet bouquet. Baka bouquet.

Bouquets one I find easiest to say but there's so many different ways to say like anybody knows. A wide aperture will create bouquet. Now, this is why photographers use what we call prime lenses, and we'll discuss them later. Different Types but what prime lens is a fixed length so it doesn't zoom. But what that allows for very wide apertures. So, we're going to use a prime in a photo to take a photo, and then we're going to create what's called bokeh in the background.

Let me show you a picture so you can see what we're actually talking about. In this image, what you can see is I've taken a picture of the subjects. And then in the background, it has some trees and there's a light reflecting and coming through those trees. And then what we get are these little circles in the background, and that's the bouquets of a Lent. That is what photographers really like. Now, if it was a bit more of a, I've shown you this we're very strong, what's called specular highlights very bright spots, so you can see the ring effect from the lens itself.

Now if I remember correctly, this was a sigma 85 millimeter prime My favorite lenses. So it creates this really powerful background. Okay, on this image. Now a lot of people would look at the image side of backgrounds too busy, but on this image, those highlights, I think add to the image. But those circles and the smoothness of the background are often what we would determine the bulk a quality of an image. So why do that?

Well, when we take an image like this, and we blur the background, and what happens is the subject jumps forward because everything in the background is blurred, and distracted. If you want to learn a little bit more about this, I suggest you take my light and composition course. Have a look at that, because we talk about Creative Photography, and how to use these sort of techniques in that course, but what I wanted you to see was a shallow depth of field is going to blur the background and bring the subject forward. And in this one because we've got a lot of highlights, we've got these little circular rings, which is also part of the bouquets when you have that in the background. If you didn't have those highlights, it would just be very smooth and creamy in the background