Mastering the exposure triangle
When you first pick up a camera, it's easy to feel like every setting is written in another language. Shutter speed, aperture, and ISO. Each one affects the look and feel of your image, but they never work alone. Together, they form what photographers call the exposure triangle, and honestly, it's the foundation of everything you'll shoot.
Here's what I tell my students: every photograph comes down to three things, light, motion, and depth. Once you understand how these variables interact, you stop guessing and start making real choices about how your camera captures the world.
The three settings that matter most
Shutter speed, aperture, and ISO make up the exposure triangle. The tricky part? Touch one, and you'll need to adjust another to keep things balanced. But that's what makes photography interesting. It's creative problem-solving with light.
| Setting | Controls | Creative effect |
|---|---|---|
| Shutter speed | How long light hits the sensor | Motion blur or freeze |
| Aperture | Size of the lens opening | Depth of field |
| ISO | Sensor sensitivity to light | Brightness and grain |
Let's break down what each one actually does.
Shutter speed: freezing or blurring motion
Shutter speed controls how long your sensor is exposed to light. It's measured in fractions of a second—1/1000, 1/250, 1/30, and so on.
Fast shutter speeds (1/1000 or faster) freeze motion. Use these for wildlife, sports, kids running around, anything that won't hold still.
Slow shutter speeds (1/30 or longer) blur motion. Think silky waterfalls, light trails from cars at night, or that dreamy look where moving water looks like fog.
Here's something I learned the hard way: light changes fast, especially when you're moving between sun and shade. Get in the habit of adjusting your shutter speed first when the light shifts. It'll save you from a lot of blown-out or muddy shots.
If you've ever wondered how to show both action and mood in one image, shutter speed is where you start. It's your way of controlling time itself.
Aperture: deciding what's sharp and what's not
Aperture is the opening in your lens that lets light through. It's measured in f-stops. f/1.8, f/4, f/11, and so on. The smaller the number, the wider the opening, which feels backward at first, but you get used to it.
Wide apertures (f/1.8 – f/2.8) allow for a lot of light and create the soft, blurry background that everyone loves in portraits. Your subject stays sharp while everything else melts away.
Narrow apertures (f/8 – f/16) let in less light but keep more of your scene in focus. This is what you want for landscapes where the foreground and background both matter.
Aperture is how you tell your viewer what matters most in the frame. Want them looking at a person's eyes? Go wide. Want them to see the whole mountain range? Go narrow.
One thing worth remembering: depth of field isn't just about making things blurry. It's about storytelling. Shallow focus pulls emotion forward. Deep focus makes everything feel important and connected.
ISO: brightness and grain
ISO controls how sensitive your camera's sensor is to light. Low numbers (100–200) are for bright conditions and give you clean, detailed images. High numbers (1600–6400) brighten things up in low light but add visible grain or noise to your photos.
Modern cameras handle high ISO way better than they used to, but there's still a tradeoff. The higher you go, the more texture and grittiness you'll see, especially in shadows.
Here's my take: don't be afraid of a little grain. Sometimes a grainy photo at dusk captures the mood better than a technically perfect one shot in harsh afternoon light. Not every image needs to be tack-sharp and noise-free. If it feels right, it is right.
How the triangle actually works
Let's say you're shooting outside on a sunny day. You set your ISO to 100 (clean image, lots of light available). You want a blurry background, so you open your aperture to f/2.8. Now there's a ton of light hitting your sensor, probably too much. So you speed up your shutter to 1/2000 to compensate. Balanced.
Now you head inside to a dimly lit cafe. You're still at f/2.8 for that background blur, but your shutter speed at 1/2000 makes everything way too dark. You slow it down to 1/100, but now your subject's hand is blurry from moving. So you bump your ISO to 800. A little grain shows up, but your shot's properly exposed and the motion is frozen. Still balanced, just different.
That's the dance. Change one thing, adjust another. After a while, it becomes instinct.
Your camera's light meter will try to guide you toward "correct" exposure, and that's helpful when you're learning. But remember: the meter measures light. You're after something more than that. Sometimes a slightly underexposed shot feels moodier and more honest. Sometimes a little overexposure makes a portrait feel airy and light. The technically perfect exposure isn't always the one that tells the best story.
Three quick exercises to build your instincts
The motion test – Find something moving (a person walking, leaves blowing, cars passing) and photograph it at three different shutter speeds: 1/1000, 1/250, and 1/30. See how motion changes the feeling of the image.
The bokeh experiment – Pick one subject and shoot it twice. Once at f/2.8, once at f/11. Look at how the background completely transforms. Notice what stays in focus and what doesn't.
The ISO challenge – Take the same photo at ISO 100 and ISO 1600. Zoom way in and compare the detail and texture. Get familiar with what your camera's grain actually looks like.
These aren't assignments—they're just ways to see what each setting actually does to your photos. You'll learn faster from shooting than from reading, I promise.
Keep practicing in all kinds of light
Don't wait around for golden hour or perfect conditions. Shoot in harsh midday sun. Shoot at dusk when the light's fading. Shoot indoors with terrible overhead lighting. The more situations you practice in, the more comfortable you'll get making quick decisions.
Mastery doesn't come from perfect conditions. It comes from curiosity and repetition. The exposure triangle stops feeling like math and starts feeling like a language. And once you're fluent, you can say exactly what you want to say with your images.
Want a printable reference guide?
I've put together a quick-start PDF with all the key settings, visual examples, and practice challenges in one place. Perfect for keeping in your camera bag or pulling up on your phone when you're out shooting. Grab your free Exposure Triangle Guide below.