The Mysterious Exposure Triangle
There is no way around it. Either you’re running your camera or your camera is running you. You have no control over the outcome of your image if you’re shooting in (the dreadful) AUTO EXPOSURE MODE. Just shoot manual. Every time. Team MANUAL MODE! 🙋🏼♀️ Who’s with me?
Where to begin?
When I took the dive into photography, I wanted to learn anything and everything. How does a camera actually work? What is it that makes an image? I needed to learn how to gauge the temperature of the light, composition, what the heck a meter was and how it worked, what a histogram was and why do I need to know about it, focus modes, artificial vs natural light, the list goes on and on and WOW - it was intimidating!
Dive in. And let me help you.
When you take structured classes or courses, you rely on a curriculum with measurable benchmarks. It’s a little tougher when you’re self taught. When I started, it was plain hard to find educators and resources. I bought books upon books upon books and I read them all. And some of them twice. Trying to understand what concepts need to come first; what really matters and doesn’t so much. And so dang much trial and error.
You need to start with the EXPOSURE TRIANGLE!
There’s just no way around it. Learn then experiment. And experiment some more. You will master your camera in such a way that you’ll capture the images that you dream of, from the point of view of the story you want to tell as well as the exposure needed to write your story.
Here’s how it works…
There are three elements that make up the exposure triangle that work together to produce a properly exposed photo; meaning not too bright, and not too dark. These elements all work in conjunction to allow a certain amount of light into your camera.
We’re talking about the lens on the camera here and every lens has different capabilities. Aperture refers to the opening in the lens that allows light to enter. The exposure value (EV) is a combination of aperture (f number), shutter speed and ISO. It indicates how much light reaches the sensor. Aperture is measured in f-stops; 1.4, 1.8, 2.0, 2.2, 2.8, 3.2, etc. A stop is a relative measure of the amount of light reaching the sensor. Imagine that there is an amount x of light coming into the sensor. If 2x amount of light reaches the sensor when you take the next shot, you’ve increased the exposure by 1 stop. On the other hand, if half of the light (x/2) reaches the sensor, the exposure of your photo has decreased by 1 stop.
A small aperture results in a shallow depth of field. A shallow depth of field, a focal point on a shallow plain, is what creates a blurry background, called bokeh (bo-kuh). Depth of Field (DoF) is the distance between the closest objects in focus and the furthest point of focus. The distance can be increased or decreased by changing the aperture (f-stop) of the lens.
Shutter speed allows you to freeze motion or show it. Faster shutter speeds freeze motion while slower shutter speeds allow you to see the motion of a scene (a person walking, cars driving, water moving, etc).
Shutter speed is how long the shutter curtain is open to allow the camera to record the image. A basic rule of thumb to achieve crisp, sharp images is to set the shutter speed no lower than the lens focal length (when you are holding your camera). In other words if you wanted a sharp, shake free shot with a 50mm lens your shutter speed would be at a minimum of 1/50th second. I always shoot much faster but I also often times and capturing children, and they are fast little movers!
ISO (eye-es-oh) is also known as film speed. The ISO number indicates how quickly a camera sensor absorbs light and I often times use it to balance the exposure. Think of ISO as caffeine for your camera. The more light that is available, the less caffeine your camera needs and alternatively, the less light your camera has access to, the more caffeine you need to feed it (bump up that ISO).
The higher the ISO, the more noise/grain that results in the images. This is because the sensor doesn’t capture more light (it doesn’t capture more information), but it amplifies the captured light signal to try to show more detail in the image. When stretching the information, the sensor isn’t able at a certain point to reproduce reality and produces the effect of noise (or grain).
A higher ISO means you can use a faster shutter speed; and adds a little more flexibility in low light situations. If you are shooting outside on a sunny day, you generally will have a lower ISO set to around 100, resulting in cleaner and less grainy images. Part of the craft is the creative eye, so if grain is what you’re after, there is no shame in that. You, at least, must know why you have it and be aiming or expecting it though.
Putting it all together with the light meter
A light meter is the tool that will help you balance all three of these elements together. The light meter lets you know exactly how much light is entering your camera. Some are more advanced than others but your camera will come with a TTL light meter (in most cases) built in! Most cameras today use a process called TTL Metering, which stands for through-the-lens. It means that your camera examines the light coming in through the lens and evaluates the brightness of the subject or scene. From there, you can adjust the settings in order to make sure your photo is exposed how you want. You’ll aim for a reading right in the center of the meter for a good exposure. If you have lots of lines to the positive, you have too much light. If you have lots of lines to the negative, you have too little light.
Your have 3 metering settings to choose from. Matrix, center weighted, and spot metering. Matrix takes into account majority of the image and will average the light coming into the lens, center weighted takes a smaller piece, about 1/3, of the image to tell you if it’s too bright or too dark, and spot metering selects only a spot that you choose. This is what is most accurate and what I use. I typically meter off skin tones to get the best exposure.