what is aperture ?
The single most important camera setting in photography is called aperture. It’s so important because it has a ton of different effects on your photos. If you don’t know what aperture is, it’s just an opening inside of your lens that can change size. Hopefully you can see that I’m changing the size of the aperture in this lens. And in today’s video, I’m going to go through every single effect that aperture has. A lot of times, you’ll only hear about two or three, but really there’s actually more like a dozen. So hopefully this video is useful for you! Here we go. This first one is so important, and it might be something you already know about, but just by virtue of the fact that aperture is the opening and closing of those blades in your lens, the larger that the opening is, the more light that you’re going to capture. And, of course, that leads to brighter photos.
So right now, I’m in front of these surprisingly tall sand dunes, and I’m going to take some sample photos where the only thing that I’m going to change is my aperture. So here’s how that looks. So, I’m starting off with an exposure that I think looks pretty good. I’m at f/8 right here, as well as 1/400th of a second and ISO 100. Now, when I open my aperture up to f/4, I’m actually capturing four times as much light. And, as you can see, my photo is much brighter by comparison. However, if I close down the aperture to f/16, I’m capturing much less light. And, as you can tell, the photo is very dark. And here’s just a video that demonstrates as I close down my aperture from f/4 all the way to f/22. So, this effect of aperture is obviously one of the biggest and most important — but there’s actually one other effect that I think matters even more. And that — is called depth of field. Now, depth of field is just how much of your photo is sharp versus out-of-focus. In a landscape like the one behind me, if I use a really large aperture — something like f/1.4 — I’ll be able to take a photo where the tree is completely sharp, but the mountain and the sand dunes behind it are very dreamy, out of focus, and blurry. However, if I use a much narrower aperture, like f/16, then I’ll be able to take a photo where everything from the front to the back of the picture is completely sharp. And that means that I have a much larger depth of field.
But which one do you actually like more? Well, that’s completely up to you. I’m sure that some photographers would prefer the out-of-focus background, while others would prefer that tack-sharp picture from front to back. And that’s why aperture is so important as a creative variable in photography. If you decide what aperture to pick based on what depth of field you need, you’ll just be a long way toward getting the types of photos that you want. Now, before the light completely runs out, I do want to talk about one other thing that aperture does in photography, which is kind of related to depth of field. And that is that it affects how any dust spots that have landed on your camera sensor are going to look in your photo. What I mean by that is pretty simple. Take a look at this picture. As you can see, there’s a lot of little dots in this photo. They don’t really look like they belong — and that’s because they don’t! They’re just specks of dust that fell onto my camera sensor.
Now, the narrower that your aperture is — in other words, the more depth of field that you have — the more defined those specks of dust are going to be. And it’s not just specks of dust, either. If you’re taking pictures maybe of the ocean, and you’ve got specks of water that have landed on your lens, they’re also going to be more defined when you use a narrower and narrower aperture. So just keep that in mind and try to avoid getting your camera too dirty, and then you won’t need to fix a bunch of stuff in post-production. Something else that aperture does is it actually affects how sharp your photos are. And that’s because it isn’t easy to design a sharp lens, especially when you’re talking about the widest aperture settings. So, behind me right now, I’ve got a hill with a lot of sand on it. It’s a pretty good example spot to just test some sharpness. So, as you can see right now, I’m popping up two photos. The first one is taken at f/1.8, and the second is at f/5.6. When I zoom in on the corners, you can definitely tell that the f/1.8 photo isn’t as sharp as the one taken at f/5.6. And that’s exactly what I’m talking about.
It’s not that you can’t use those wider aperture settings, but when you do, you just have to be aware that you might lose a little bit of sharpness. I’m going to use this same spot to talk about another effect that aperture has on sharpness, and that is called diffraction. Now, diffraction is when any waves — including waves of light — bend through a narrow opening and start to interfere with each other. In photography, this means that you’re going to get lower sharpness any time that your aperture is too small. Now here’s an example of a photo taken at f/5.6 versus f/22. When I zoom in, you can see that the photo taken at f/22 — which is a much narrower aperture — isn’t nearly as sharp. And that is because of diffraction Now, unlike the previous example of lens sharpness, the amount of diffraction in your photo doesn’t really depend on the quality of the lens that you have. Every lens out there is going to show more diffraction the smaller the aperture that you use. But, again, that doesn’t mean that you should avoid those apertures.
You just need to be aware that you might lose some sharpness with them. Now, the next few that I’d like to talk about are actually kind of similar to what I was saying about lens quality. And that’s because a loss in sharpness is not the only lens problem — or lens aberration — that your aperture can affect. There’s actually several others. For example, you’ve got vignetting, which is when the corners of your photo get noticeably darker. There’s also coma, which is when bright points of light, especially something like stars, can start to look like streaks when they’re in the corner of your photo. And then focus shift, which is where the point that you focused on can actually move a little bit — usually not that much — as you stop down to a different aperture value. And just like before, you are a lot more likely to see these lens aberrations when you’re shooting at wider apertures, maybe something like f/1.4 to f/2.8. Now, I do want to emphasize that — as important as these effects of aperture are — they are not the most important thing in a photo.
So, if you do need a wide aperture setting for whatever creative purposes you have, definitely go for it. Lens aberrations aren’t ideal but they’re very unlikely to ruin your photo. As a landscape photographer, one of my favorite things that aperture can do is something called the “sunstar effect.” And this is when a really small and bright source of light — especially the sun, but also something like street lamps at night — can turn into a really interesting star pattern when you use a very narrow aperture. For example, in this video here, I’m using an aperture of f/22, which is the narrowest aperture on my lens. And in this video, I’m using an aperture of f/4. You can tell that the sun in this video isn’t very defined; to me, it looked a lot better in the previous video Now, the actual aperture of f/22 is probably going to be overkill most of the time. Remember, an aperture that’s that narrow is going to have a lot more diffraction.
But even an aperture like f/11 or f/16 can get you some really interesting sunstar effects — although it does depend on the lens that you’re using, and the number of aperture blades, and the shape of the aperture blades inside that lens. But either way, once you set an aperture like f/11 or f/16, you’re going to get some pretty interesting photos. While you’re busy pointing your lens at the sun, you’ll probably also notice something called flare. And this is just internal reflections within your lens that show up in your photos. I’m sure you’ve seen this before. And, for what it’s worth, depending on the aperture that you use, you might actually have different amounts of flare, or different shapes to the flare that you’ve got. Here’s an example photo that I took at f/8 versus f/16. As you can see, the photo at f/16 has noticeably more flare. Now, there’s no set pattern as to which apertures do better in terms of flare. It’s really something that you’ve got to test out for your particular equipment. But once you do, you’ll be able to take pictures in backlit situations with a little bit more knowledge about how to make those photos turn out well. The next one is that aperture also has to do with the quality of your background blur.
And this isn’t the same thing as depth of field that I already talked about. What I actually mean is that any points of light that are out of focus in your photo are going to take on the shape of the aperture blades in your lens. Here’s an example where you can see that pretty clearly. As you can tell, when I zoom in on this photo, the out-of-focus blur isn’t a perfect circle. It looks a little bit uneven. And that’s because the aperture blades in my lens weren’t a perfect circle either. And the key here is that the appearance of this blur is going to change depending on the aperture that you use. Here’s four example photos taken with my 24mm f/1.4 lens, and you can see that as I use a smaller aperture, it’s not just the size but also the shape of the background blur that changes. Now, personally, I prefer the look of f/1.4 and f/1.8 in this case, but really it’s down to personal preference. The one thing that I would emphasize, though, is that the largest aperture on your lens isn’t always going to have the best looking background blur. A lot of times, it is, but sometimes you’ll get better looking background blur by stopping down maybe a third of a stop or two thirds of a stop.
You just have to test this out for yourself. But once you do, you’ll have a better idea of what aperture to use. As the day wraps up, I’ll also wrap up this video by talking about one last thing that aperture can do in photography. And that is that, in conditions like this where it’s very dark, you can actually focus a lot more easily — especially autofocus, but manual focus as well — when you have a lens with a large maximum aperture. For example, for the two videos that I’m showing right now, the lens on the left has a maximum aperture of f/1.4. However, the video on the right is taken with a lens with an f/4 maximum aperture that lets in only one eighth as much light as the video on the left. Now, as you can see, the video on the right is having a lot harder time focusing on this subject, whereas the one on the left can do it really easily. And that’s why a lot of sports and wildlife photographers in particular care so much about the maximum aperture of their lens. It just helps them get that shot in darker conditions where they otherwise might have missed it. And there you go! That’s everything that aperture does in photography. I hope you learned something from this video. It’s certainly more than just capturing light and changing depth of field.