Lens Basics - Aperture
All right, the next major aspect of lenses after focal length is aperture. So aperture is gonna control how much light is coming into the camera, but it also controls how much depth of field you have. And so, let's take a look at an example of what micro four thirds lenses look like at different apertures. And so in this example we're at 1.4, and you can see around the seven-inch mark here, we've got it in focus, a little bit in front and a little bit behind. Those red hash marks indicate where it is in sharp focus. And we have a large region that is out of focus. And so if you want very shallow depth of field, you get a lens that can go all the way down to 1. or in the case of some Olympus lenses, all the way down to 1.2. Now as we stop our aperture down, we're gonna get more depth of field. You're gonna see those red lines spread out as it grows a little bit as we change from one aperture setting to the next. And so this is gonna continue along the whole collection of lenses. Now it ...
never really changes dramatically at one particular setting. And there isn't one setting that you should always have for something in general. It's gonna be a variety of compromises of what is necessary for a particular photograph. And so f/16 we are now getting great depth of field. And it's not totally in perfect sharp focus in this particular example, but it does extend much, much further in this case. And so you want to become familiar with all the different apertures and when you would employ them for different types of subject. When you go from an aperture of 5.6 for instance to f/4, it's called opening up the aperture, for pretty obvious reasons. When you go down to f/8, you're stopping it down and you're getting more depth of field, but it's gonna let in less light, so you're gonna have to accommodate these changes with changes in shutter speeds or ISO or some other manner. And so important to know. So depth of field is controlled by changing the aperture, but it's also controlled by the focal length of the lens and the shooting distance that you are from the subject. And you want to keep that in mind as we go through the next collection of images, which are examples of shooting at different apertures with different lenses. So let's kind of take a walk through the different apertures and why you might use this. Now I'm gonna go all the way down to 1.2 because Olympus frankly makes a bunch of cool lenses that go all the way down to 1.2. There's a couple of really good reasons why you might be interested in these lenses, and the first is shooting with really shallow depth of field. Look at those eyes and the beard in very sharp focus, but the background is not. And that's because the photographer wanted you to focus a particular area in this picture. And so for portrait photography, these shallow depth of field lenses are fantastic. I found great use for it when I was shooting a lantern festival. Now this takes place at night, and I wanted to shoot with a fast lens. So I chose the 17-millimeter f/1.2 lens. And working with the in-camera stabilization in the Olympus cameras, I was able to shoot in pretty much pure black. I mean the only thing illuminating this are the candles illuminating the lanterns. And I got lots of great, sharp photos here. And so this was chosen not so much for the shallow depth of field, but for the technical reasons of letting in lots of light. It just happens to be as a secondary characteristic artistically, I like that shallow depth of field, that we have one object in focus and the rest of them kind of nice and blurry, out of focus. So with an aperture of f/2, focusing on a subject very close to the camera, you're gonna tend to get very shallow depth of field. And even though you're at f/2, using a wider-angle lens with subjects that are further away, you can still get great depth of field at f/2. This lens is utilized here probably more for the fact that it was under somewhat lower light conditions. And so focusing further away, you're gonna get a little bit more depth of field. And so it is kind of confusing to those who are new in photography that there's these three different factors. There's the aperture, the focal length, and how close you are to your subjects that are all affecting how much depth of field you get. And in these examples, I wanted to show you that you can get either shallow or great depth of field with any aperture, depending on the other factors. And so an aperture of 2.8, this is one of my favorite photos that I've seen from anybody. I've become a very big fan of Frank T. Smith. Haven't met him, but I've become a big fan because I love his work and love the blue in this. And so nice sharp focus on the eyes, the background is nice and blurry, you don't need to go down to 1.2 to shoot this. This was done at f/2.8. Getting more depth of field at 2.8 is achieved with a wide-angle lens focused a little bit further away. Very good. If you are going to be working under low light conditions, I would really encourage looking at lenses that have maximum apertures of 2.8 or faster. F/4 lens with the 300, the 300 f/4 lens is gonna allow you to get very, very shallow depth of field, especially when you get very close up like this. Shooting with a wider-angle lens at f/4, you're gonna get great depth of field, especially when you're focused a little bit further away. 5.6 can be very good for shooting portraits as well. It ensures sharpness over more than just a very narrow sliver of range. Working with a wider-angle lens, f/5.6 is gonna allow pretty much everything to be in focus. Closing down to f/8, you're definitely gonna be getting more in focus, but you're also shooting where these lenses are their very sharpest, towards the middle range of the aperture. It varies from lens to lens where you're gonna get the best sharpness on it, but typically it's toward these middle apertures. When you get into the world of macro photography, you will notice that shallow depth of field is a common challenge with everything that you shoot. It can sometimes be very handy and work for you artistically like in this shot. You get to have a couple of flower petals in focus, and then it kind of softly goes out of focus from there. Going down to f/11, you're definitely gonna be getting more depth of field with all of your lenses, especially your wide-angle lens, like an eight-millimeter lens here, keeping everything in focus from the foreground to the background. And so if you do want a subject in the foreground and the background in focus, stopping down to f/11 is gonna help you achieve that. The smallest opening on many of these lenses is gonna be f/16. Sometimes you do it for depth of field. In this case, I suspect the photographer chose to use it to get a little bit slower shutter speed to get a little bit of motion blur in that subway behind the subject. But if you do want really sharp focus from foreground to background, stopping down to f/16 is gonna give you that greatest opportunity for sharpness over the complete range. It's pretty rare that you stop down to f/22. You would think that you would get lots of depth of field, but when you are focused really close on a subject, there are limitations as to how much you can get in focus. I was choosing f/22 for this particular shot not 'cause I wanted f/22, it's because I wanted the effect of blocking that light out so that I could use a slower shutter speed to employ a panning technique. And so all of the lenses will have a great range that you can open and close them down to, and it's about making smart choices for why you want to choose that particular aperture. All right. I want to ask everybody a tricky question. This is something that tripped me up when I was new into photography. Here's a couple of Olympus lenses, the 25 f/1. and the 25 1.2. And the question is, if each of these lenses are set to 2.8, will they have the same exposure and depth of field? And think about that for a moment. I'll let you answer it on your own. I don't have my studio audience here, so I can't be asking you for it right now. And I know when I was new to photography, I would have said, "Well that 25 1.2 is a really expensive, "cool, awesome lens, so it must be giving me "a better exposure and shallower depth of field." But the fact of the matter is they're gonna exhibit the same exposure and the same depth of field between them. And so the 25 1.2 lens is not doing anything different than the other lens. Now they are very different lenses, and there are different characteristics. There's different size focusing ring on it, and it's got a manual distance scale on it, and there's a different level of sharpness between them, and there's different weights, and a lot of other things. But if you're shooting at 2.8, you're gonna get the same results. Where that 1.2 lens really comes into its own is when you start shooting it at 1.4 and 1.2. It doesn't mean you shouldn't shoot it at those other numbers, but it's gonna have the same effect as those other lenses. So as you look through these different lenses, they're going to have different maximum apertures. The maximum on any of their lenses at this time is 1.2. A lot of their zoom lenses will have a variable maximum aperture, like this 4 to 5.6 example here, and some of their zoom lenses will have a fixed maximum aperture, which means that as you zoom the lens back and forth, the maximum aperture is 2.8. At all times, you can change it from 2.8 to 4, to 5.6, to 8, 11, and so on. And so when fixed aperture, that doesn't mean that it's the only aperture available. It just means that that's what's the maximum aperture on a particular lens. So let's take this 25 1.2 lens as an example. So what does this mean? Well the one colon refers to the focal length of the lens. And so this is actually a math problem. And the math problem is the focal length divided by 1.2. And so we take 25 millimeters, divide it by 1.2, and if you were to measure the opening of the lens, not necessarily the front of the lens, but the opening of the lens, it would be 20.8 millimeters in size. Okay? So let's compare a couple of standard lenses. The 25 1.8 has an opening of 13.9, and that lens that we just talked about, the 25 1.2, has an opening of 20.8. And so this is why that 25 1.2 is gonna cost more. The glass needs to be bigger. It's a little bit more difficult to design. And so they have different lenses to adhere to different needs and different price points. And so you're gonna see a lot of different options from Olympus that has kind of a basic standard lens, and then they're gonna have a professional-quality lens, depending on what your needs are. The maximum aperture in their lenses will range anywhere from 1.2 to f/4 with their primes, but they do have f/2 lenses, they have f/2.8 lenses. It just depends on what that lens's intended use is. With their zoom lenses, they are gonna have a large collection of zoom lenses have a variable maximum aperture that varies a little bit depending on the particular lens. And these are gonna be good general purpose lenses. For those getting a little bit more serious, you might appreciate having a fixed maximum aperture. That way, your aperture doesn't change as you zoom back and forth. So f/4 or in many cases f/2.8 is gonna be the maximum aperture on those lenses. Now the apertures that go from 3.5 to 5.6. There's a lot of reasons to own this type of lens. They're a very versatile zoom range. They're less expensive. These are a good starter system to have. And people who are gonna want to do this are gonna be people just into general photography, maybe your general standard family photographer, or people into travel. Next up are the lenses that open up to f/2 and 1.8. And a lot of these are very small little primes. And so they're very good under low light conditions. They're gonna allow you to have a little bit faster shutter speeds. And as I said, they're small in size, so they tend to be pretty good for travel photography. And so any sort of indoor work, you're doing work with people where you need a little bit faster shutter speeds, and travel photography, these tend to be really good. Now some of the latest generation of lenses from Olympus are these lenses that go down to 1.2. And these are gonna be the best that they have when it comes to low light work. If you need faster shutter speeds or you need lower depth of field, they're the best you're gonna be able to get. And so if you do a lot of work indoors, you do a lot of work with people, you do event photography like a wedding, for instance, where you need a little bit faster shutter speeds, these are gonna be very, very helpful lenses. Now when you listen to people like me talk about lenses, we speak very reverently about these fast lenses. And there's a reason that we are in awe and love these fast lenses. And so there is a deal to why we think they're important. They allow you to use faster shutter speeds, which can be very helpful. They allow you to use lower ISO's, which can improve your image quality. They can allow you to shoot in very, very low light situations and with very shallow depth of field to tell a particular type of story. Now they don't always, but they tend to also be of better construction. Because it's bigger glass, they tend to have more metal construction. They tend to be weather-sealed. It seems like the companies that make fast lenses decide, we need to make these things be able to be handled by professionals. And so they tend to be made a little bit better. They tend to have more features. But it does vary from lens to lens. So we're gonna have three different categories of lenses. We're gonna have the standard M. Zuiko lenses, which is your good, general purpose lenses. We then have the premium category, which are gonna be a group of smaller primes that let in more light, and they have a lot of different, various features that make them a little bit more premium. And then we have the pro series. And this is ones where they are using very fast apertures and really top quality everything. And so we're gonna be looking at these lessons more closely in the next section.