Exposure isn’t an easy part of photography, especially if you’re just starting to learn about it. Your camera has dozens of buttons and hundreds of menu options — how do you even begin to set everything correctly? But it’s not as bad as you might think. There are only two camera settings that affect exposure: shutter speed and aperture. These are also the two most important settings in all of photography. In this article, I’ll introduce shutter speed and aperture (as well as a third variable, ISO) and explain in depth how to use them properly. Once you master exposure, your photos will skyrocket in quality.
If you want to master exposure, reading about it isn’t enough. You also need to go out into the field and practice what you’ve learned. There’s no quick-and-dirty way to learn things.
Still, it isn’t all bad. Yes, shutter speed and aperture (as well as ISO) take some effort to learn. That’s unavoidable. But when you’re starting out, you only need to know the basics in order to lay a solid groundwork for the future.
That’s what this article is for. It’s very in-depth, and it will teach you all the basics that you need to know. By the end, you’ll have a very solid foundation in exposure. I tried to make this guide as comprehensive as possible.
If you’d like to skip to a particular section, here’s a quick outline of the tutorial:
- Shutter speed
- A recommendation for most exposures
Otherwise, just start at the top and read everything carefully. By the end, you’ll have a very strong understanding of shutter speed, aperture, and ISO. You’ll be ready to go out and use your knowledge to take better photos.
We’ll start with a good one. Shutter speed isn’t particularly difficult — it’s just the amount of time that your camera spends taking a picture.
This could be 1/100 of a second, or 1/10 of a second, or three seconds, or five minutes. Some people build custom cameras that take decades to capture a single photo.
Your camera won’t let you take a decades-long photo. Instead, the longest allowable shutter speed tends to be around 30 seconds, although it does depend upon your camera.
On my Nikon D800e, I can shoot any shutter speed from 1/8000 second to 30 seconds. That’s a pretty large range! Other cameras generally allow similar settings.
So, why does shutter speed really matter? There are two main reasons.
First, as you would expect, a long shutter speed (several seconds) lets in a ton of light. If you take a normal daytime photo with a 30-second shutter speed, you’ll end up with an image that is completely white.
The opposite is true, too — a quick shutter speed only lets in a tiny amount of light. If I take a photo on a dark night with a 1/8000-second shutter speed, the photo will be completely black.
I’ve included a series of examples below. Here, 1/25 second was too dark, and 1/3 second was overexposed. Hopefully, this gives you an idea of the brightness differences with shutter speed:
All of this should make sense so far. Shutter speed is pretty easy.
The only other effect that matters here is the motion blur in your images. Not surprisingly, a long shutter speed (such as five seconds) captures any significant movement during the exposure. If a person walks by, they might appear as a featureless streak across the image. That’s called motion blur.
By comparison, a quick shutter speed (such as 1/1000 second) does a much better job freezing motion in your photo — even something moving quickly. You can photograph a waterfall at 1/1000 second and see individual droplets frozen in midair. To the naked eye, they might have been invisible.
Take a look at the images below. Here, I was taking pictures on a windy day, and the foreground grass was moving quickly. Depending upon my shutter speed, there was a major difference in motion blur:
There are two types of motion blur that you may encounter due to your shutter speed: camera blur and subject blur.
If you’re doing handheld photography, camera blur could be very significant. It’s impossible to hold your camera perfectly still while you’re taking a picture, and even slight shake can lead to very blurry photos. That’s one reason why many photographers end up using tripods! (There are other benefits of tripods, too.)
However, although a tripod protects against camera movement, it does nothing to prevent scene movement. For example, if you’re taking landscape photos on a windy day — even with a tripod — you might end up with blurry leaves and grass in your photo, as in the comparison above. The same is true if you photograph anything else that moves, such as a person or an animal. This is called subject blur.
Sometimes, you can use camera or subject blur artistically, and it looks good. For example, if you’re photographing clouds as they pass through a valley, a long shutter speed might be a nice touch:
However, most of the time, you’ll probably want to eliminate motion blur. If that’s your goal, you need to pick a shutter speed that is quick enough to freeze any movement.
So, what shutter speed should you use? Is there a good range that tends to provide sharp photos?
Not really. It all depends upon some outside factors — most importantly, the amount of movement in your scene. If your subject is moving very quickly, you’ll need a fast shutter speed. If your subject is standing still, or only moving very slowly, you can get away with a longer shutter speed.
There is, however, one quick tip that you might find useful if you tend to handhold your camera. It only applies to camera blur, but it’s still a good starting point. Specifically, use a shutter speed that is equal to 1/(equivalent focal length). You’ll keep camera blur to a minimum.
For example, if your lens is a 50mm equivalent, shoot at 1/50 second or faster. If your lens is a 20mm equivalent, shoot at 1/20 second or faster. And so on.
Equivalent means that you have to multiply by your camera’s crop factor. It’s very easy to find your crop factor online.
If you have a micro four-thirds camera, your crop factor is 2x. If you have an aps-c or DX sensor, your crop factor is about 1.5x.
Whatever lens you’re using, all you have to do is multiply it by that number. So, if you’re using a 20mm lens on an aps-c camera, your equivalent focal length is 20mm × 1.5, or 30mm. So, you can handhold that lens at 1/30 second without introducing too much blur.
Although this equation can be useful, it only matters for handheld camera blur. If your subject is moving quickly, this rule won’t do anything to help. That’s also true if you’re using a tripod, since (ideally) there won’t be any camera blur to eliminate in the first place.
This is why you can’t just fall back on a rule and follow it blindly. If you’re taking pictures at an auto race, and you try to use 1/(equivalent focal length) to find your shutter speed, it probably won’t end well. You might decide to shoot at 1/100 second, when you really need something like 1/500 or 1/1000 second to freeze your subject perfectly.
So, although tips like this can be helpful from time to time, they don’t always apply. Sure, they’re a good place to start, but most photographers will outgrow them quickly.
Instead, the best route is just to keep practicing. Over time, you’ll build a good mental picture of the shutter speeds you can use in a particular environment without risking motion blur. Whether that’s 1/250 second, 1/10 second, or 20 seconds, it’ll be second nature.
You can get to that point sooner than you might think. It just takes a bit of practice.
What is aperture? This is aperture:
Your lens probably looks something like this. The shape in the middle is called the aperture. It’s made up of several aperture blades — nine of them in this case, but your lens may differ.
Aperture blades work a lot like the pupil in your eyes. At night, your pupils dilate so that you can see more easily. The same is true for aperture. When it’s dark, you can open the aperture blades in your lens and let in more light.
Aperture is written as f/Number. For example, you can have an aperture of f/2, or f/8, or f/16, and so on.
Before I talk about the properties of aperture, let’s get one thing out of the way:
Aperture is a fraction.
I’ll say it again:
Aperture is a fraction.
Aperture is a fraction.
If you repeat it enough times, you’ll remember it. This is the biggest mistake that beginners make when they talk about aperture. If you get this wrong, it confuses everyone.
Which aperture is larger — f/2 or f/16?
You already know the answer, because aperture is a fraction. 1/2 is bigger than 1/16. So, f/2 is the larger aperture.
Typically, the largest aperture you can set will be something like f/1.4, f/1.8, f/2, f/2.8, f/3.5, f/4, or f/5.6. It changes from lens to lens.
The smallest aperture on most lenses is something like f/16, f/22, or f/32.
This diagram demonstrates the physical sizes of various aperture settings:
Now that we’ve got that covered, and you understand why f/2 is larger than f/16, let’s get started.
Which aperture setting is best for photography? It depends upon the photo. Aperture influences many parts of an image, but it has two effects that are more important than anything else: exposure and depth of field.
1. Aperture and exposure (brightness)
The larger your aperture, the brighter your photo. Again, your pupils work just like this, too — they open or close to let in different amounts of light. So, if you want to change the exposure of a photo, aperture is crucial.
A large aperture lets in more light. Apertures like f/1.4 and f/2 practically let you see in the dark.
On the flip side, a small aperture like f/16 (with nearly closed aperture blades) barely lets in any light at all. If you try to photograph Milky Way at f/16, your final image will be essentially black.
This effect makes sense, and it’s why we consider aperture to be a component of exposure. When you open and close the “pupil” of your lens, you change the physical amount of light that reaches your camera sensor.
By changing your aperture and shutter speed settings, you can capture exactly the amount of light you want — resulting in a photo with the proper exposure. That’s what makes aperture so powerful.
2. Aperture and depth of field
The other important effect of aperture is on depth of field.
Depth of field is the amount of your scene, from front to back, that appears sharp. In a landscape photo, your depth of field might be huge, stretching from the foreground to the horizon. In a portrait photo, your depth of field might be so thin that only your subject’s eyes are sharp.
Aperture changes your depth of field. That’s a big deal. Getting the right depth of field in a photo will alter the way it looks completely.
To be specific, small apertures (like f/16) give you a large depth of field. If you want everything from front to back to appear sharp, that’s what you should use.
Large apertures (like f/2.8) capture a much thinner depth of field, with a shallow focus effect. They’re great if you’re trying to isolate just a small part of your subject, making everything else blurred.
Here’s a sample comparison:
That’s a huge difference! The photograph on the left has a larger depth of field, which means that more of the image appears sharp from front to back. But the f/2.8 photo on the right has a pleasant shallow focus effect. In this case, it looks like the better image.
For what it’s worth, this is one of those things that you just need to memorize. Unless you spend a lot of time thinking about optical physics, there’s no quick way to visualize why a large aperture like f/2 leads to a thin depth of field, or why a small aperture like f/16 leads to a huge depth of field — but it does, and that’s very important to photography.
In practice, you’ll see this effect pretty clearly. As you click the aperture smaller and smaller, your photos will get darker and darker, and your depth of field will grow progressively larger. (Remember, too, that you can brighten the photo back to normal by using a longer shutter speed.)
The more photos you take, the less you’ll have to think about these effects. They’ll become second nature.
3. The aperture scale
The shutter speed scale is easy to remember. An exposure of 1/200 second lets in half as much light as an exposure of 1/100 second. A ten second shutter speed is twice as bright as a five second shutter speed.
Unfortunately, aperture isn’t quite so intuitive. This is the scale it follows instead:
From f/1.4 to f/2.0 (or any other one-stop jump) you’ll capture half as much light. You’ll also increase your depth of field.
If it helps you remember things, this entire chart is based upon the square root of two (roughly 1.4). To move from one stop to the next, multiply your f-number by 1.4.
For what it’s worth, you might be able to set values beyond this chart, depending upon your lens. And, most of the time, you’ll be able to use apertures between these stops, too (such as f/1.8 or f/6.3).
Typically, the sharpest apertures will be somewhere in the middle of the range. On most lenses, f/4, f/5.6, and f/8 are three of the sharpest apertures. However, this varies wildly from lens to lens. And sharpness shouldn’t be your main concern, either. It’s better to have a photo with the proper depth of field, even if it means that some low-lying pixels have a bit less detail.
ISO (Not part of exposure)
ISO is an interesting one.
In theory, it’s a simple concept, but photographers have kicked it around and analyzed it so much that it’s hardly recognizable any more. If you ever mention ISO in a discussion online, tread carefully.
My advice is not to worry about the most technical side of things at this point. There’s more than enough time for engineer-level discussions once you master the basics. Here’s what you do need to know about ISO: it’s similar a sound amplifier, but for your photos.
In music, an amplifier obviously makes things louder when they’re too quiet — but it also amplifies weird audio artifacts (like background hiss and distortion) that aren’t desirable.
Photography is a lot like that, but with ISO. You can brighten your photo by raising the ISO, without a doubt. However, if you do so (rather than by using a longer shutter speed or wider aperture), it’s not all good news. Your photos will be brighter, but you’ll also emphasize grain (otherwise known as noise) and weird-colored pixels in the images along the way.
Take a look at the comparison below:
Here, the photo on the right looks much grainier/noisier, and it has some strange color shifts in the shadows. That’s because I used ISO 25,600 here, which is an extremely high ISO (higher than what most photographers tend to set).
ISO is different from aperture and shutter speed because it doesn’t change the amount of light that reaches your camera sensor. That’s why it isn’t technically part of your exposure. Instead, it merely brightens the image you’ve already captured. In many ways, raising your ISO is similar to just brightening the photo in post-processing software, although brightening via ISO tends to give you better image quality.
Sometimes, a higher ISO is necessary. Say that you’re shooting sports, for example. You might be at a shutter speed of 1/500 second to freeze the motion, which doesn’t let in very much light. And, perhaps you’ve maxed-out your aperture to the largest option that your lens allows (something like f/2.8). But your final photo still might be too dark.
What can you do about it? Simple: Raise the ISO.
The ISO scale is easy to remember. The higher the number, the brighter your image will be. The main stops on the ISO scale are 100, 200, 400, 800, 1600, 3200, and 6400. Some cameras go beyond this range, in either direction, such as my camera’s ability to shoot at ISO 25,600. Also, you can set intermediate ISO values, such as ISO 640 or ISO 1250.
The lowest ISO on your camera is called the “base ISO.” Typically, the base ISO will be 100, but some cameras have ISO 64, ISO 200, or something else instead. This is just the lowest native ISO on your camera. If you set your base ISO and expose your photo properly, you’ll end up with the best possible image quality, and the lowest amount of visible noise.
Certain cameras have extreme “LO” values for ISO. Avoid using those settings, since they’re completely simulated and actually lower your image quality. The same goes for simulated “HI” ISO settings. They don’t provide any benefit over just brightening the photo in post-processing, and in fact can harm your overall image quality.
Take a look at the series of images below. In this case, the farthest photo on the left (taken at my camera’s base ISO of 100) is way too dark. By increasing my ISO, though, I ended up with something that looks pretty good. Sure, there’s more noise if you zoom into the pixels, but a noisy photo is better than one where you can’t even see the subject.
So, how much noise exists in the ISO 1600 photo above? Is it still workable? In fact, the overall amount is not too bad. Here’s a crop from the ISO 1600 photo above:
That seems pretty impressive to me. I wouldn’t mind shooting with this camera at ISO 1600. However, it’s still best to use your base ISO whenever possible, and brighten your photo with a longer shutter speed or a wider aperture instead.
Unfortunately, you have to let in a lot of light in order to capture a well-exposed photo at ISO 100. That’s fine if it’s bright out, or if you’re photographing a nonmoving scene from a tripod (since tripods let you use longer shutter speeds). But it won’t always work. That’s what makes ISO adjustments so powerful.
So, don’t be hesitant to use higher ISO values if the scene requires it. With sports or wildlife, for example, you’ll be shooting at higher ISOs very often. Although that isn’t ideal, it’s better than missing the photo because you’re shooting everything at ISO 100.
When you’re starting out, don’t get dragged into a deep debate on the technical side of ISO. Just use it like you would expect. Keep your ISO at the base value whenever possible. But, if your photos would be too dark (and you’ve already maxed out your shutter speed and aperture), it’s time to raise the ISO. If you follow those tips, you’ll be good.
A recommendation for most exposures
There are no universal tips for always setting the perfect exposure. Still, a lot of beginners have no clue where to start. If that’s true for you, you’ll want more than just general advice about shutter speed, aperture, and ISO. You want specific starting points that help you put all this knowledge into practice more easily.
For that reason, I’ve added some recommended settings below for different genres of photography. Fair warning, though — these are very general suggestions that might not apply to whatever specific subject you’re photographing. They’re simply intended to be basic tips in case you have no clue where to begin:
1. Typical landscape photography (not at night, or of a fast-moving subject)
- Use a tripod. You can read more here on why that’s so important.
- Switch to aperture-priority mode, where the camera automatically sets the shutter speed, and you manually select the aperture.
- Shoot at f/8 in general, but use f/11 or f/16 instead if you need more depth of field (such as with a nearby foreground, or if you’re using a telephoto lens). This is on a full-frame camera. Use your camera’s equivalent aperture by dividing these numbers by your crop factor.
- Set the ISO to its base value.
- Let your shutter speed fall wherever it needs to be for the proper exposure.
- Watch your highlights. Don’t overexpose any of them. If necessary, use negative exposure compensation to darken the photo. Why? It’s simply easier to brighten shadows in post-processing than to darken overexposed highlights.
2. Portrait photography (not using a flash)
- Shoot handheld, use a tripod, or use a monopod. In this case, the best option isn’t set in stone. Use whatever you’re most comfortable with, or whatever works for your shoot.
- Use aperture-priority mode.
- Choose whatever aperture gives you a pleasing depth of field — typically, something like f/2.8 or f/1.4, but it depends upon the look you want (as well as the settings that your lens offers).
- Watch your shutter speed. If you start to notice motion blur, your shutter speed is too long, and you need something quicker.
- Keep your ISO low, but don’t be afraid to raise it if your aperture and shutter speed aren’t letting in enough light. In darker environments, especially, you’ll probably need to raise your ISO.
- Once again, don’t overexpose any highlights. Use negative exposure compensation if necessary.
3. Sports and wildlife photography
- Shoot handheld or use a monopod.
- Use aperture-priority mode.
- Use your largest aperture, such as f/2.8 or f/4.
- Watch your shutter speed very, very carefully. You’ll need something fast (like 1/500 or 1/1000 second) to freeze fast-moving sports.
- Most likely, you’ll need to raise your ISO to a value that lets you use such a fast shutter speed. It’s worth the tradeoff. Noise is better than motion blur.
- And again, don’t overexpose any highlights.
4. Recommended exposure settings roundup
These recommended settings aren’t universally accurate, but they should be useful for a beginner who wants a starting point. At any rate, they certainly work better than switching to manual mode and attempting to pick the right settings before you know what anything does. (Though, that’s still a good way to learn, if you aren’t taking critical photos.)
An important point here is that you’ll outgrow these suggestions organically as you become more and more skilled at photography. I didn’t mention some special-case suggestions above (such as using a large aperture for Milky Way photos), but you’ll realize them pretty quickly in the field. My hope is that, eventually, you’ll add your own points to each of these lists and expand on new concepts you’ve learned.
Exposure can seem complicated, but it’s one of the most important technical topics to know if you want to take high quality photos. Hopefully, this article is a good introduction that makes things a bit easier to understand.
If you’re still confused by some of these concepts, the best thing you can do is go out and test them yourself. Play around with your exposure settings, as well as ISO. Pay attention to how they affect a photo. Most of all, keep practicing. Exposure is something that you’ll never stop improving, and, without a doubt, it is worth the effort to learn.