If you’re a new DSLR (Digital Single Lens Reflex) camera owner, you already know that your machine is powerful and capable of greatness. But knowing how to unlock that greatness requires training and moving out of your comfort zone to move off the AUTO setting. To really get creative control over your photos, you need to master some basic photography principles, such as aperture. But what is aperture? Aperture is the size of the opening in your DSLR’s lens which helps determine the amount of light that reaches the camera’s sensor. Understanding aperture will enable you to understand light dynamics, zoom constraints, and ultimately, how to take the best pictures you possibly can. Understanding aperture will also demonstrate what a huge difference a smaller (or bigger) aperture makes in various light paths.
Ken Shultz has over 30 years of photojournalism and will be presenting this lecture on beginner to advanced DSLR techniques. The lecture transcript below focuses on understanding aperture through historical lens and past techniques, to the point where you’ll be completely comfortable going manual on your camera. It will also outline how to adjust the mode of your camera to adjust the aperture manually, as well as changing lens for optimal aperture. By the end of this course, which contains 7 additional sections to this transcript, you should be totally adept at the photo triangle (frame, light, and focus), autofocus points, effects of depth of field, isolating subjects, and more.
Welcome back. This is the second part in our Exposure Series. We have three videos describing exposure and important settings. The first one we spoke about was ISO and gave you a general introduction about what exposure is. And we included the tool, the histogram, a way of seeing if your images are well exposed before you take it and after you take it. A lot of cameras – even the older ones – will have it as an option to preview images and see the histogram. But in the newer models, with the live view display, you can actually get a histogram view and see what exposure you’re going to take before you take the photograph.
In this video I’m going to talk about aperture, but I just want to quickly give you an overview of what happens to the light path when you take a photograph. Essentially what happens is the light comes through the lens and it’s affected by the optics of the lens. And the first obstacle it comes across, or the first adjuster other than your focus, is the actual aperture. And that’s the hole that lets through the light. Then the light goes through the lens, through the aperture, and when you take the photograph, this mirror actually pops up. So, you can see here, we have the mirror of the camera. I’m going to set it to bulb mode here so I can actually show you what happens when you press the shutter. So, you press the shutter and the mirror pops out of the way and exposes the sensor. So that was the mirror popping out of the way and then the shutter exposing the sensor and closing, and then the mirror popping down. Those are the things that happen to the light path when you take a photograph. So, the aperture is one of the first key things that affects the amount of light that goes onto the sensor; it’s one of the first things that affects the exposure.
The best way to show you what aperture is, is to actually show you on one of these older manual lenses, because that actually allows you to change the aperture on the lens. If you have a look, in the center there, you’ll see a little dot. And when I move the aperture ring, you can see it changing. So that, on this particular lens, F22– aperture is kind of strange because it’s a ratio actually; the larger number is a smaller aperture. So, it’s kind of like a fraction. If it has a bigger number at the bottom, it’s actually a smaller aperture. So, F22 is the smallest aperture. And then we click it to F16, 11, eight, 5.6, and then 3.3; that’s as large as this particular lens goes. That gives you an idea of what apertures are. So, the smaller the number, it’s actually the wider and the more light it lets through.
Lenses will actually come with an aperture mention; its maximum aperture. So, this lens is actually a 3.3. And it’s a zoom lens, and this one at full zoom is actually 4.5. So when it’s at 70 mm – we remember that focal length video we went through, which 70 is zoomed in, and when you open it up to 36, which is a wider view focal length, then this lens can handle 3.3. So, with this lens, the F’s start according to the zoom level. Now, you get other lenses, like the one on here, which has a fixed aperture – or fixed F start for the lens. So, whether you’re on 16 or whether you’re on 35, the maximum aperture can stay at 2.8. So, this lens is a 16 to 35 F 2.8 lens, which means 2.8 is the widest aperture it can have. Now, that’s wider than this one. This one being 3.3, it couldn’t handle as much light as this lens. So, having a smaller number there means you can actually open up the lens wider, which effectively lets more light into your sensor, which lets you take photographs in lower light conditions.
To get a larger aperture still, you pretty much need to jump over onto prime lenses. This is a relatively inexpensive 50 mm prime lens, and this is a 1.8 lens. That means that the aperture on this can go all the way up to 1.8, so you can actually see through that view there that it’s quite a lot more light going through there; the aperture’s a lot wider than that 3.3 lens. So, prime lenses are used a lot when you’re dealing with darker areas, especially with event photographers when they’re taking wedding photographs and they’re in like a church environment, where flashes may be prohibited. Then, if you get a prime lens that’s wide enough, you can actually be able to take photographs in lower light conditions without using flash, so that’s very handy just because it’s letting a lot more light onto your sensor.
That’s basically what aperture is. It’s simple to understand that it’s just the smaller the number, the bigger aperture and the more light that gets let on the film. Now, the interesting side effect of the aperture is, a wide aperture will have a very narrow focusing depth. The point of focus will be very narrow and it will get blurred before and after very quickly. And the narrow aperture will extend the amount that’s in focus. But I’ll go a lot more into that in the depth of field video in the focus section.
That pretty much concludes what aperture’s all about. So, to really experiment and to understand aperture, one of the simplest ways, and in fact, one of the ways that I mostly shoot on these cameras is to take it off program or full auto mode. So, if you take it off the green square or the green camera symbol – which is the full auto – and the P off that, and you turn it over to AV or AP mode, which is aperture priority.
Now, in your camera manual, it will tell you exactly what it’s called. It’s usually A or AP – aperture priority – or sometimes AV – aperture value – in the case of the Canons here. Now, this is our first step beyond shooting on auto all the time. So, now what we’ve done is, we’ve changed the camera into a mode where if you look through the camera now and you move your controller – which is usually on the top near the shutter button – when you actually rotate that now, half press your shutter and rotate. Now you’ll see numbers in your viewfinder changing, and the one closest to the scale – in this case the exposure value – is the aperture value. You may need to look in your manual to see exactly where that is in your viewfinder, but you’ll see that. Now, with this lens, I can close the aperture all the way to 22 and then I can open it up all the way to 2.8. Your lens may stop at four or 5.6, depending on what lens you have and what zoom setting you have.
What you’ll notice is, in a particular given situation, if you choose the widest aperture – in other words, the smallest number there – that will automatically adjust the shutter speed accordingly. So, the widest aperture will let the most light in, which will allow you to actually have a quicker shutter speed. And if you just practice, then you can change apertures and just experiment with the effect it has on the shutter speed, because they basically balance each other out all the time. That’ll pretty much lead us directly into our next video, which is shutter speed.
That concludes the aperture video. So, we’ve dealt with framing our image and now we’ve dealt with two of the components of light, which are dealing with exposure specifically, which is the sensitivity of the sensor, which is the ISO. And now we’e looked at aperture, which is the amount of light that the lens lets through to the sensor. That leads us straight into our next video, which is the shutter speed, which is how quickly the shutter moves. Jump right into that one when you’re ready.