What is the exposure triangle? If you’ve come across this page you may have started to explore more manual forms of photography. Or maybe you just want to know how to truly control your camera (guess what…it’s easier than you think!). So here is my quickest guide to the exposure triangle for portrait photographers. I hesitated on writing the “exposure triangle” because to be totally honest this always sounds so…what’s the word…institutional. It just seems like you’re sitting in a stuffy room listening to someone drone on about aperture and shutter speed and ISO and not getting anywhere closer to understanding anything about how these things all work together or how you should be using them. Trust me…I’ve been there.
But I have also taught the exposure triangle every single year of my teaching career (or two or three times those years I taught night school and summer programs). So let’s dive into this not-actually-so-scary part of photography. I will keep this as simple as possible. While some things are…well…a little technical, most of it is just truly understanding your camera meter and how to control the light that comes into your camera.
If you know how to meter your camera then you may think you have this whole exposure triangle thing down pat. That you don’t actually need to know about the exposure triangle. But that’s sort of like riding your bike with training wheels. You can get from point A to point B but you haven’t actually mastered riding the bike. You know? Alright, let’s get to the nitty gritty.
the exposure triangle
The exposure triangle is made up of 3 main parts (hence, the triangle). Aperture, shutter speed, and ISO. Each of these parts changes how much light gets into your camera, but they do so in entirely different ways. But all of them work together—kind of light a clutch, gas pedal, and gear shifter in a car. They each need to play their part to drive the vehicle (err: to take the photo). The exposure triangle is perfect for portrait photographers and is easier than you think!
Shutter speed is how fast or slow the shutter in the back of the camera opens to allow light onto the film plane (or the sensor in digital photography). This is actually the noise you hear when you take a photo. That satisfying click click is actually the mirror going up and the shutter opening and closing. This is made up of a bunch of numbers ranging from 1-2000 on older cameras or from 30″-4000 on newer digital cameras.
Shutter speed has a very important job, it controls motion and movement in your photos. You can change the shutter speed by using the command dial on your camera. Freezing motion is a higher numbers, whereas dragging motion is with lower numbers.
Lower number = longer time = more light to the sensor
higher number = shorter time = less light reaches the sensor
So where do you start? Well it all depends on what you want to get with the motion. But a good rule of thumb is to always hand hold (if you are physically holding your camera up to your face) your camera at 1/60 or above. Another trick is to have the shutter speed be about double of what your lens length is (so if you shoot with a 50mm lens then keep as close to 100 as you can).
Aperture is the portrait photographers best friend. This is what makes a professional portrait really different than something taken on your phone or by your friend with an entry level DSLR and kit lens.
Aperture is the opening inside the lens of your camera. It controls how large the opening is that allows light into your camera that passes through the shutter (much like your own eye). Aperture is also often referred to as f/stop—the terms are interchangeable. Aperture is made up of some strange numbers (2.8, 5.6, 22, etc.) and it controls how much of your photo is in focus, called depth of field. A large number means everything is in focus, where a small number focuses clearly on a single object (called shallow depth of field). Aperture is changed with your front command dial (if you have one) or by holding the +/- button on the top of the camera and using your rear command dial.
Lower number = larger opening = shallow depth of field
Higher number = smaller opening = deeper depth of field
Again, the question becomes what f-stop do you use? And again the answer depends on what you want to photograph. Do you want to take a portrait where the person is in focus but the background is blurry? Then choose the lowest aperture number possible. Are you trying to get a beautiful landscape and you want everything in focus? Choose a larger aperture like f/11or f/22.
ISO is what we most often call film speed. It actually stands for “International Organization for Standardization” and is the main way that all film is tested and metered and processed. Years ago this was called ASA, which was the “American Standards Association”, but was essentially the same for film speeds. Some older film cameras may have ASA instead of ISO but they work the same and are basically interchangeable terms. There is no longer an American Standards Association, just know they mean the same thing if you see them on a camera.
Which ISO should you choose? 400 is a very safe place to start for most people. I usually keep my ISO on the same standard settings for daylight, indoor, and night. If I am photographing portraits with a good amount of daylight, then I shoot at 100 or 200. The finer grain is best for portraits, landscapes, and anything where you want a crisper image. But as soon as that light starts getting low—or your step inside—you may have to change the ISO settings. As a wedding photographer, at receptions or in dark churches I often have to go as high as 1600 or 3200. Newer cameras are much more capable of creating a less grainy image at higher ISO settings, but it still is not ideal (you will see a degradation in the grain, or the noise, of your image). My best advice is to still nail your metering if you are at higher ISO settings. If you bring up the exposure in post-production you will see alllllll the grain that you didn’t see when it was underexposed.
Metering using the exposure triangle
So where do you start with the exposure triangle for someone like portrait photographers? You start with the meter. The meter is inside your camera (and sometimes shows on the back window as well). You want the small single line to be as close to zero as you can while you are composing your image (which is why I use the one inside the camera that looks slightly different than this video). But essentially you want the line(s) to be at zero (in the middle) so the image is neither overexposed or underexposed. If when you take the photo it seems too dark or light you can, of course, adjust from there. The meter is doing its best job but depending on the scene you are shooting it may read it a little dark or light.
Now you know all the settings, so basically you start with the most important element first and meter from there. So here is how you would use the exposure triangle as a portrait photographer, I’ll give an example. It’s a warm May day and I am photographing graduation photos here in Boston. I start with my ISO at 100 or 200 because it’s bright and sunny. Then I change my aperture to something low (1.4-2.8) so I can isolate my subject from the background. Lastly, I meter my shutter speed to whatever the lighting calls for. In most cases this should be plenty of light to give me a high enough shutter speed to avoid camera shake since the light is plentiful.
A second example. It’s an evening engagement session and I am posing my couple in front of a subway train. I want the couple to be in focus but I want to get the fun movement of the subway car. What are my settings? First is still ISO and I am going to start somewhere easy, like 400. This middle/low ISO should give me enough wiggle room for my other settings. Then I choose my shutter speed to be lower than 60, but not so low that I can’t keep my couple in focus. I’ll start with 30. I’ll meter the scene changing my f/stop to whatever the camera meter asks for and tell my couple to stand very still while the train really starts moving. Easy…right?!
Now that you have some idea of how the exposure triangle works for portrait photographers you should go out and explore. See if you can see the difference when you try some of these settings. Getting used to paying attention to ALL the settings while shooting in manual does get to be a bit much at times, but you get used to it VERY fast. If that seems daunting—try the free email course on how to get off auto mode using priority modes on your camera.