 So I'm doing the research for today's lesson. I learned something really amazing. I'm still like shocked about this. Did you know that a water droplet is a lens? I was like, woohoo, how cool is that? So as you can probably tell, today's lesson is going to be about, it's going to be about lenses. So in this image, if you look in the background, you can see that there is a bridge back here. You can see me kind of doing a tracing of the shape in the background. That bridge is out of focus because it's kind of far off in the distance and we're zoomed in. Our eyes are focusing in on, or the camera and this photograph is focusing in on these water droplets. They're sitting on a window, looking in the direction of the bridge. Now if you look inside of each of those water droplets, you can see this bridge. There it is. Little spans. You can see I just copied that. You can see it's flipping it. So you can see that it's also upside down, which is something that lenses do. You can see the cable stretching out between it. Maybe if we were to look at the top of this water droplet, so if we were to look from maybe like up here and slice the water droplet in half, it would look something like this. So you'd have your bridge on the other side over here and the light is then falling from that bridge. It's then being sent out in lots and lots and lots of different directions. So from each little point, it's going in every direction. But the lens is looking at it from one particular point. The lens, the light is coming off of it, hitting the lens and then traveling through the lens. And in this case, we've got our eye or our sensor down here and the light is then going down onto whatever it is that it's being focused onto. So the really amazing thing about lenses is that they're all over the place. And you don't maybe think about it, but this is actually a lens. An eye is a lens. It's one of the most advanced and amazing lenses that there are out there. And we'll talk a little bit more about that a little bit later. Now this is what a lens of a camera looks like on the inside. This is a diagram of a lens. And so we're going to go through and maybe label this. I'm going to delete that. That was just telling us a little bit of information about the lens. I'm also going to delete this because it's just telling us where the focus, focusing elements of this lens are. Right here you can see that one, there's lots and lots of little pieces. And these are actually made out of glass. So they're going to be sort of maybe we'll color them blue because everyone likes to color glass blue. And each piece of glass is called an element. Now you put these pieces of glass together in a group and they are called a group. Pretty simple, right? So you've got your elements and your groups. And in this lens you have a whole bunch of pieces. You have a whole bunch of elements and then you also have a whole bunch of groups. You have another group here, another group here, one here and then even just sort of the single one in the back here which is still I think maybe possibly technically called a group. To put them all together you need one big piece of metal or lots and lots and lots of pieces of metal or plastic or whatever the lens is made out of. So we're going to make here what's called the barrel. So here we've got our barrel and connecting to the barrel are lots and lots of little pieces of metal that are holding all of these pieces of glass in place or sometimes lenses are also made out of plastic so they don't necessarily have to be a piece of glass. And so here we can have maybe divide our lens into a few pieces. Our barrel is connected right here for example. Some often see that on a lens. There will be many sort of different outside pieces. And this lens maybe has a mount right here that connects it to the camera. So here's your camera. We've already talked about cameras in this course so you kind of we're not going to explain too much about that. Back here is maybe your sensor. And the light is then coming through the lens. Boop, flying in this way all the way through all of this and then landing here on the sensor in the back. So how does all what are all these other pieces in here? There's quite a lot to building a lens. So we go through and diagram some of that. Now we've already got our barrel here. We've talked about that. Now this lens I remember if you remember I erased a line that was on the bottom here and it was said it was internal focusing which basically means that each of these little pieces of glass or each of these groups is on sort of a roller. So we'll put like a little roller right here. And they are sliding back and forth to focus. And those are all connected with some complicated screws and pulleys and stuff like that. And they're connected to a ring that's on the whole outside of the lens so we'll make it right here. And you as the user you're holding the camera with your one hand so one hand is holding the camera right here. That's not a very good hand. Sorry about that. And you are then turning this ring on the outside of the barrel so it's sort of maybe like a rubber gummy piece of something and you're turning it in one way or the other. And that is then sliding these pieces of glass back and forth and letting you focus the image that you're seeing on the other side. So maybe you have a tree that you want to focus on. It's not going to be yellow. It's going to be brown. We'll put our tree right here. So you're focusing it on that tree and it's a certain distance from you. So to set that you need to turn your focus ring, zoom in or not zoom but focus in on that tree. And then it'll appear focused here in your sensor and in the eye that is looking through the prism that is looking at the tree. And you'll see your tree will then be focused onto your sensor or onto your film. We don't want to discriminate against people who use film. So there we've got our, let's see, that is called our focus ring. And inside of the camera at another spot is another important part of the lens which is also often connected to a ring and this is called the aperture. And connected to the aperture is also another ring. It might be like right here. Have some numbers on it often. And this will be called the aperture. I'm just going to put it A period aperture ring. So the A stands for A period, stands for aperture like you see down here. And the aperture is basically just a little, it's like a, kind of like the shutters on a window. It opens and closes and we'll talk about aperture in more in-depth in future lessons and we've already kind of discussed it in a very broad sense already in this course. The aperture just closes and opens. It's like a big barn door allowing more or less light into this lens. So here you've got your elements, your groups, your barrel, your ring, your focus ring, your aperture, your aperture ring, all that stuff. And the only thing that I really want to tell you about before we move on to the next slide is about the lens coating. Now on the front end of this lens is going to be sort of a layer of, it's going to kind of maybe look purple or red or blue. It depends on the type of lens you have, the type of coating it has. But there will be some sort of synthetic material that's put on the front that's called the lens coating. And lens coating is important because it allows you to shoot into light sources without getting what's called ghosting, which just means that the light source inside of the lens will make all kinds of weird, the light will bounce around and make it kind of look funny on the other end when it's actually being looked at as a picture. So a lens coating is important to helping keep that light focused and making sure that when it hits the lens it just goes straight in and it doesn't bounce around and make all kinds of, make a big mess on your photo. So lens coating is very important. It's important because you want to protect it. You don't want to get it scratched. And you also don't want to change it by using maybe some sort of lens cleaning fluid that might affect it in some way. So just as a piece of information that's really important for all photographers, protect your lens coatings. Protect your lens on both ends. You're actually going to be able to have, you're going to have lens coating on both sides. And you're going to want to protect the glass and the coating on both ends of your lenses. We're going to do a really quick little literacy lesson here about how to read about the lens without even having to open the manual. So you can see here on this lens it's actually detracted, it's put inside of the, it's pulled itself inside of the camera, which most compact cameras do. You can see here that the lens is made by Canon. You can see that it is a zoom lens. And we'll talk about what that is here in a second. And you can see that it is a three-time zoom. And all this means is that it takes the widest version of your photo. So say you are looking through the viewfinder and you see this scene right here and you've got a person in the room who you want to maybe zoom in on. If you go from the widest setting, the widest setting that your lens will do, and you zoom in on that person say right here, the difference between this widest image and the smallest image is a zoom factor of three. And that actually, you can actually, if you do the math right here, this 3.8 and the 17.4, that is reflected in these numbers down here. Now 4.8 is actually the real size of the zoom lens. And there's something called 35 millimeter equivalent. So if you're reading a lot of times in the literature, you'll see a 35 millimeter equivalent marked. And that just has to do with the size if it was on a 35 millimeter camera. This camera has a tiny little sensor that's a lot smaller than 35 millimeters. So it has a smaller lens. But what they're saying when you see a 35 millimeter equivalent, they're saying if the lens was bigger, if the sensor was a 35 millimeter sensor like this yellow would be, then this number would be a lot bigger. It would stay instead of 5, it might say 18 or something like that. So that's just an important piece of information. Now over here, you can see 1 to 2.8 dash and then 4.9. And this right here is the widest possible aperture at these different settings. So at 5.8, your aperture, your maximum aperture is 2.8. And at 17.4, your maximum aperture is 4.9. The widest aperture is very important. It's very important actually. And having a widest aperture of 2.8 for a camera like this is actually not too bad. 2.8 just means that it's a very wide aperture. If it was 5.6, it would be smaller. And thereby a slower lens. So you don't necessarily want a slower lens. The reason you don't want a slower lens is if you're in a dark room and you're taking a photograph, you want as much light as you possibly can to get inside of that camera. So at 2.8 is letting in more light than a 5.6. So you can see here when you're zooming in, when you're zoomed in at three times, zoom, that you're getting less light than you are when you're shooting at the widest angle. And we'll talk about why that's important in the exposure lesson, but it's just important to know the smaller these numbers, the better. Now here you can see two different types of lenses. You can see here this is a zoom lens. And this is what's called a fixed or a prime lens. Now a prime lens is just 50 millimeters. So it just has one length that it can go. And this one right here is actually if you look closely, I think it says 28, yep, so this is a 28 to 200 millimeter lens. So this means that this lens can zoom in, so it can take a really wide shot, and then you could zoom in and take a really small shot. But this lens over here can only take a wide shot. It can only take, well, what's called a normal shot, because 50 millimeters is what's called normal. And it can't zoom. There's no zoom factor on it. The only way that you can zoom in on this lens is by walking closer to the subject. Now how about we take a look at what that would look like. So we've got our zoom lens. Let's say we have that 28 to 200 millimeter lens. When you've got it on your camera, so here's your camera, here's your lens, and you're looking out over a room. Let's say you've got a really long table right here and some people are sitting at it. You're taking a picture of them. You've got your lens on, you're looking to the viewfinder, and a little ways away, you're pretty far away from them. Maybe you're, let's say, you're two meters or something like that. So you're looking at them, and you've got your lens on at 28 millimeters. It's going to look something like this. You're going to see, you're going to see have a pretty wide range of view from left to right, and you're going to be able to see quite a lot, also up and down. This is it, the zoom goes in both directions. Now say you zoom in from 28 millimeters to 50. Fifty millimeters might look something like this. So you're cutting off maybe your Aunt Joe and your, or your Uncle Joe and your Aunt Betty on these sides. So your 50 millimeter is going to be a little bit more narrow, and this is actually pretty exaggerated, probably be a little bit wider than that. Now say you wanted to zoom in on just one person, it was maybe sitting in the very center of the table, and maybe you would move up to your 200. So here we've got that. It would be your range, this would be maybe your 200 millimeter. So here you can, when you're looking at a 200 millimeter image, all of this right here has been cut off. You can't see any of that. All you're seeing is this one person right here. This is your picture about. And in this case over here maybe your picture would actually look something like this, and in this other picture you're obviously looking at a much, much wider image, something like that. And all of this is just basically called focal length, so the length of your lens. All right, so that was your lesson about lenses. In the next video we're going to talk about what the difference is between a good lens and a bad lens.