I shoved my phone in my husband’s face to show him a picture I’d taken of the New York skyline. “It’s good, right?” I asked, way too proud of myself because, frankly, it was not good. “Well,” he said. “Imagine how good it would look if you knew what you were doing.” I rolled my eyes but took him up on his offer to teach me about exposure.
A good photo is a properly exposed photo, and all that means is the right amount of light hits the photo in all the right places. I always had a vague understanding of my camera’s exposure settings. I knew they had something to do with the lighting situation. But when I bothered to learn how exposure actually works, my photos went from “that’s cute” to “wow, that actually doesn’t suck.”
Exposure depends on three factors: aperture, shutter speed, and ISO sensitivity , which is also referred to as the “exposure triangle.”
Not all cameras will allow you to change these settings, but if you’re at all interested in taking photos that don’t completely suck, it’s worth learning how they work nonetheless.
Aperture
Aperture is measured in f-stops and it’s basically the amount of light your lens lets in. A wide aperture lets in more light, and the wider the aperture, the lower the f-stop (f/1.0 is pretty wide). So what’s with the f?
The f/stop is a ratio. As photographer Matt Cole explains, it’s the ratio between the diameter of the aperture in the lens and the lens’s focal length. He further explains:
The focal length is generally measured in millimeters, so we’ll stick with those as our unit of measure. On a 50mm lens, f/2 is saying that the diameter of the aperture is 25mm. The ratio is: 50/25 = 2.
It gets a little more complicated than that, but for photography neophytes like me, all you really need to know is that the f/stop measures how much light your camera allows in. Wide apertures will have a lower number, letting in a lot of light, and narrow apertures will have a higher number, letting in less light. When you shoot something super bright, like the moon, you want a narrow aperture. It’s sort of like a window on a bright day—you don’t need to open the curtains very wide before light floods the room. On a rainy day, though, you might need to open them as wide as possible to get any light in the room at all.
Shutter Speed
While aperture measures dimension, shutter speed measures time: how long your camera’s shutter is open to let in the light. The faster the shutter opens and closes, the less light can get in. If it’s open for a long time, it will let in quite a bit of light. When you shoot photos of the night sky and want to capture the stars, you’ll have a long shutter speed because you need all the light you can get at night (unless you’re shooting the moon, which is already bright).
If you let in too much light, your photos can look blurry. This can happen if you move the camera, too. Going back to the night sky example, this is why it’s important to keep your camera extremely stable—otherwise, you can get blurry stars or light trails (on the other hand, if you know what you’re doing, this is kind of a cool trick). When you’re trying to take a photo of a hummingbird or something else in action, though, you want a super quick shutter speed. This way, you get just enough light to capture one flap of the bird’s wings, as opposed to keeping it open longer and capturing a few flaps which then translate to a blurry bird.
Shutter speeds are measured in mere fractions of a second. An action shot might call for a shutter speed of 1/1200 seconds. But this varies depending on the image. If you’re taking a night sky photo or trying to get cool light trails, you might want to keep the shutter open for up to 30 seconds. Your settings depend on the image you’re trying to get, the lighting, and your other two exposure settings.
ISO Sensitivity
ISO is the third part of the triangle. It stands for International Standards Organization, as it’s a standardized scale for measuring sensitivity to light.
In film photography, ISO tells you how sensitive film is to incoming light. In digital photography, your camera has its own sensor with its own ISO settings. The lower the ISO number, the less sensitive your camera is to light and the darker your photo will be. You can take a brighter picture without flash by adjusting the ISO upward. The problem is, a too-high ISO can take all the detail out of your photo. The Bastard’s Book of Photography puts it this way:
First of all, you want to keep ISO as low as possible. Unlike with shutter speed and aperture, there really isn’t a good reason to have higher-than-needed ISO. Because no one really wants the effect that high ISO creates...It creates noise, random pixelation that can smudge the fine detail in an image. I suppose that some photographers do enjoy this look when it evokes the “grain” texture that sensitive film has. But as colored pixels, it’s not usually flattering.
In auto mode, your camera should try to pick the lowest ISO setting possible for the scene. However, you can dig into the setting in manual mode to adjust for night shots or any other situations when the lighting is less than ideal.
The Exposure Settings for Five Types of Photos
I won’t pretend to be a professional or even a good photographer, but once I learned the exposure triangle and how each factor works together, I was surprised at how much better my photos came out. Here are a few examples and the exposure settings I used.
The Moon
Moon photographers follow something called the Looney 11 Rule. The “11” refers to the f-stop, which seems to be the most important exposure setting here. Here’s what the rule calls for specifically, depending on the moon:
Full moon: Shutter speed at 1/125, aperture at f/11, and ISO 250
Quarter moon: Shutter speed at 1/60, aperture at f/11, and ISO 250
Thin crescent moon: Shutter speed at 1/15, aperture at f/2.8, and ISO 250
These settings will get you in the ballpark, but when you shoot your own moon photo, play around with the settings a bit to see what yields the best results.
The above photo isn’t the best picture of the moon that’s ever been taken, but it beats the glowing bulb photos I used to take of the moon, where it was indistinguishable from a street lamp.
The settings I used for the above photo:
Aperture: f/11
Shutter speed: 1/320
ISO250
Not any lens will do with moon photos, though. You’ll need a telephoto lens with a focal length of at least 300mm. Also, use a tripod to make sure your camera is stabilized, because even a small move can make your photo blurry and ruin it. I took about twenty pictures of a blurry moon before I got the one above, and I also used the camera’s timer to make sure there was no movement.
Street Photography
When you’re out with your camera on the street, you often have to be pretty fast to get the shot you want. On a sunny day, here’s where PetaPixel says your settings should sit:
Aperture: f/16
Shutter speed: higher than 1/200
ISO between 200-400
Remember, the higher your shutter speed, the faster your shutter opens and closes, which makes it more conducive to catching a subject in motion: someone walking, a bicyclist, etc. They recommend using a wide angle lens to capture everything. A telephoto lens works, too, but you might look like a paparazzo walking down the street with a giant lens. Here’s the lens I use for pretty much everything.
In the above photo (of fellow Lifehacker writer Stephanie Lee!) , I used the following settings:
Aperture: f/3.2
Shutter speed: 1/500
ISO: 320
Stephanie looks great, but exposure-wise, it’s not the best shot. It was kind of a cloudy day, which is why my aperture is wider, but it’s still probably set way too wide. Looking back, maybe I should’ve narrowed the aperture more and just hiked up the ISO. Live and learn.
Action or Bird Photography
Whether it’s a basketball game or a big bird flapping it’s wings, the key to taking great action shots is your shutter speed. Photography Mad recommends starting at 1/500. As for aperture and ISO, you can probably stick to the same range as street photography shots (around f/16, ISO 200-400), depending on the lighting.
In the above photo, I tried to take ten different pictures of this bird extending its wings, and they all came out blurry. I adjusted my shutter speed to 1/2500 to catch the action. Also, I used a telephoto lens to capture this shot at a distance, since most birds don’t really let you get up close and personal.
Water in Motion
Shutter speed is the name of the game with waterfall photography, too. Again, you need a quick shutter speed to catch the water in motion. The setting depends on how fast the water is moving, so it can be hard to gauge. It also depends on what kind of photo you want. For those ethereal, powdery waterfall photos, here’s what Phototuts+ recommends:
Aperture: f/16
ISO: the lowest your camera will allow
Shutter speed: 2 seconds
Again, this is a ballpark and it’s meant to recreate a specific type of waterfall photo. For the photo above, I wanted to capture the movement of the waterfall, all the detail, including the tiny droplets you see. Here are the settings I used:
Aperture: f/7
Shutter speed: 1/2000
ISO: 320
A quick shutter speed ensures you capture the subject in action. Again, if that’s not what you’re going for, you’ll use a much slower speed, maybe around one to two seconds. Experiment and see what works for you, but these settings should get you started.
The Night Sky and Stars
One of my favorite subjects to photograph is the night sky. I suck at it, but that’s what makes it fun. It’s just a lot of trial and error. Here’s where Nikon USA says you should keep your settings for decent night sky photos:
Aperture: as wide as your lens will allow
Shutter speed: 20 seconds
ISO: They say to increase as needed, but try a range of 4000 to 12800
Photographing the night sky can be tricky because you often want to get the sky and the landscape along with it, and those can call for different exposure settings. Your job is to find a good balance that gets both (or you can take two separate photos and edit, but that’s a different post). For the night sky photo above, I used the following settings:
Aperture: f4
Shutter speed: 15 seconds
ISO: 1250
As you can see, my shutter speed and ISO are a lot farther off than their ballpark suggestion but this is partially because I wanted to get the brightly lit landscape in the photo, too.
Obviously, I am not a pro. It’s possible to take a much better photos. But that’s the point: learning how exposure settings work together is crucial to figuring out how to take better photos. I think I’ve come a long way from pointing and shooting, and all it took was learning a few basics and,of course, experimenting.