This post was last updated on August 25th, 2014
Grab your cameras folks—it’s time for another edition of How to Take Better Travel Photos! If you’re new to the series, check out our previous lessons here. (If you’ve forgotten what your histogram should look like, I especially recommend giving this one a read-through before continuing.)
Today we’re going to go over what the exposure triangle is, its different parts, and how they affect your photos.
These are the fundamentals to getting out of Auto. And let’s be honest, if you have that fancy DSLR, you really, really don’t want to be shooting on Auto all the time. So let’s get started!
The Exposure Triangle
The exposure triangle is composed of 3 parts: shutter speed, aperture, and ISO.
Each of these corners of the triangle relate to light and how it enters and interacts with your camera. For the perfect histogram, these three variables need to be balanced. It keeps the triangle happy. It also means you always need to have all three elements in mind to compose the perfect image.
So for example, if your shutter speed is extremely fast, the aperture and ISO will need to shift in order to balance your exposure triangle.
Now, let’s break down the triangle:
Shutter speed is the amount of time the shutter is open. Think of the shutter like the eye to your camera. The shutter speed is essentially how much time it takes for your camera’s eye to blink.
So the faster your shutter speed, the less movement and light you’ll capture in your photos. Great for sports or pesky animals who just don’t want to say still. Take this for example:
Animals and wildlife rarely pose for long so in order to photograph them clearly a faster shutter speed is needed. Now let’s do the opposite. A slow shutter speed allows my camera to take in more light and motion.
This was a photo I took while standing in the middle of the street in Taiwan. (And who said photography wasn’t a dangerous job?)
The shutter speed has been slowed down to 1/8. Basically the eye of the camera was open for 1/8 of a second and gathered all the light that hit the sensor during that time. This is a great way to capture movement in your photos.
Here’s another great example of the benefits of a slow shutter speed. When we were recently photographing the Northern Lights, I slowed my shutter speed all the way down to 20 seconds. This allowed my camera to absorb as much light from the Aurora as possible.
To control your shutter speed, set your camera to S Priority Mode (Tv on some models). Your speed will show in fractions of a second. So if you set your speed to 1500, that’s really a speed of 1/1500—a really, really fast blink. If you set the speed to 30, that’s a 30 second blink—really, really slow. Your aperture and ISO will automatically adjust accordingly when shooting in S Priority.
This one can be a little trickier to understand at first, but with some practice it’s not so bad.
The aperture in your camera is basically a hole that light passes through. If we go back to our eye analogy, then the aperture is like the pupil—and it’s size determines how much light gets in. When the hole is large, more light can get in; when the hole is small, less light gets in.
Controlling the aperture is also how we control the depth of field. I think of depth of field as how much of the scene your camera can focus on at one time. When our aperture is a large hole our depth of field is small. When our aperture is a small hole, our depth of field is large. With me so far? Here’s a little something for the visual learners.
This shows a shallow depth of field. It’s great for focusing on one thing, such as a beautiful bride and groom. I use shallow depth of field extensively for portraits and food. It singles out your subject and ‘blurs’ what is around it. And let’s be honest—there’s nothing more important than you and your food.
On the other end, here’s a large depth of field:
I use a large depth of field when shooting landscapes because you want to be able to see all the details from the front of the image all the way to the back. Everything is important.
So how do you control it? Flip that dial on your camera to A Priority. Depth of field is measured in increments called F-stops. A small F-number means a larger aperture and therefore a shallow depth of field.
What the F..?
Yeah, f-stops are great. Got your camera in your hand? Lets go through it again. Set the dial to A and you’ll see a number with an f in front of it.
So twist that dial and the number will change. I like to use f8 for general shooting as it’s right around midrange. Push down to f3.8 (depending on your lens you can go down further) and your depth of field is now shallow. If you think of it this way it’s quite simple: the smaller the f # = the smaller the depth of field. Just keep in the back of your head that the hole in your camera isn’t small, it’s actually big and letting in a lot of light. Your shutter speed and ISO will automatically adjust accordingly when shooting in A Priority.
Probably the most commonly overlooked corner of the triangle is ISO.
ISO measures the sensitivity of your camera to light. I like to think of it as how much brain power your camera uses to take a picture. The usual range of ISO goes from 100 to 6400. At ISO 100, your camera is using all of its brain power to gather a very detailed, “noise free” image. At ISO 6400 your camera sacrifices quality in order to record the picture; this allows you to take pictures in lower light, but at the cost of “noise.”
Noise can also be referred to as grain. They look like discolored little spots. The Exposure Guide has some great examples of photos at different ISO values to show you how the quality is effected.
You’ll notice that there is no ISO priority mode on your camera. Many cameras have an Auto ISO when using Shutter or Aperture Priority Mode, which is helpful when first getting started. Once you get the hang of things, you can adjust your settings to be able to control ISO along with Aperture or Shutter Speed (2 sides of the triangle at once). This way you know you are getting the highest-quality image. There should be a button on your camera somewhere that says ISO. If you’re having trouble finding it check your manual.
As a general guide, I like to keep my ISO as low a number as possible to produce high-quality images. But sometimes, especially at night, this just isn’t possible.
If you’re controlling 2 parts of the triangle, it is possible to unbalance your triangle to the point where your camera can’t compensate. Your photo will turn out too light or (more often) too dark. You can check your exposure meter to make sure your photo is balanced before you take the shot. A potentially bad exposure will show lines off the center or sometimes a blinking meter. Your exposure meter looks something like this:
Cameras are surprisingly smart, and they are getting smarter every year. However, they will never be as good as the human brain. By getting out of ‘auto’ and controlling your aperture, shutter speed, and ISO, you can drastically improve your pictures. Give it a shot and then be sure to tell me your results!
This was just a basic introduction to the Exposure Triangle. Be sure to tell me any questions you have in the comments below! Want more detail about a particular element of the triangle in a future photography lesson? Let me know!
~ Natural Light: Explains the different qualities of natural light and how to use them to your advantage.
~ Understanding the Histogram: Learn how this graph can inform you about everything in your image.
~ HDR Photography: Explains what HDR is and how to use it.
~ Composition: An introduction to the artistic side of creating an eye-catching photo.
~ Dan R Moore Photo Shop: Discover and purchase photos from around the world