Understanding exposure. This is easily one of the most crucial things in photography to help you capture and create photographs that not only tell a story, but show it in such a way that truly highlights the subjects in amazing detail and clarity. I can’t count how many photographs I have taken in previous years where I was still in a learning process of understanding how my camera worked and completely blew it when it came to capturing a moment that will unfortunately, never come my way again. If I had a better understanding of one tool at the time, it would have addressed a lot of my issues. There is a certain tool that photographers have used through the years and is one of the keys to unlocking a fuller understanding of camera body systems and lenses and how they work together to create an image. This is called the exposure triangle.

When you look at other photographers’ images, as well as your own, sometimes you may notice they are underexposed. There is not enough light illuminating the subject or composition, or, things may be too illuminated, where the elements in the frame are too bright and the details of the image seem to be “blown out,” due to the fact that the lighter areas of the image are too lightened. Another common mistake is that an image may be blurry, not sharp, or noisy. This can apply to the main subject, many subjects, or the entire composition. This can make for a very frustrating time if you spent hours out in the field capturing some potentially great moments and places, yet when you drop your RAW images into Lightroom or Photoshop for post-processing, you see that they are lacking in one of these areas, or all of them.

In order to capture a photo that we can see, there are a few things that need to happen. Getting down to the base level first, we see that the word photograph essentially means “to draw with light.” It comes from the Greek word for photo, which means light and graph, or to draw. Interesting when you think about your own photos in this regard isn’t it? It gives a bit more clarity to the process of capturing an image. So in order to capture a photo, we have to control two things:

A.) The amount of light that is exposed or (let in) to a photosensitive surface

B.) The sensitivity of the surface to the light itself

The camera body and the lens work together in tandem to control exposure by using this exposure triangle. A digital sensor or film is a surface that will collect the crucial information on how much light was obtained in order to display the photo. So, lets get into it and break down what this tool is.

The three sections of this “Photography Trinity” are Shutter Speed, Aperture, and ISO. These camera and lens controls work simultaneously together to balance and regulate the amount or quantity of light that makes its way to the photosensitive surface within your camera body as well as the sensitivity of the surface itself. I won’t be going into a lot of detail for each of these within this post, but in the future I am planning to have certain blog posts dedicated to each one of these, deep diving to explain the more intricate details of each of them and how they are such an important foundation of photography.

So, let’s take a look at the first one: Shutter Speed. This is what gets adjusted by you, the shooter, (if you are shooting in Shutter Priority or Manual Mode) to decide how fast or slow you want the shutter to close, leading to it’s eventual release. Depending on what you are looking to achieve as a photographer within the context of the subject you are shooting, the feeling you want to convey, etc. you can use shutter speed as an immediate creative filter in your mind before even adjusting it on your camera. (Having this kind of vision for your shots will also save you time and occasional frustration when you are on location shooting.) For instance, if you are taking a photo of a waterfall, would you want to capture or freeze the motion of the water to possibly convey the sheer power of the falls, or, would you want to allow more time to go by, allowing for more volume of water to be displayed in the composition? This is your choice to make and you can adjust your shutter speed accordingly to get the result you want to achieve to display for yourself and your audience.

Here are a couple of images from Burville Falls here in upstate New York that reflect the effects that I just spoke about as it relates to shutter speed:

If you decrease the shutter speed, you will generate or induce motion blur for moving objects like people, waterfalls, animals, or cars. This will also result in a higher overall exposure value, and the outcome will be more light and a brighter image. If you increase the shutter speed, you will be able to freeze moving objects. This will result in a lower exposure value and the outcome will be less light and a darker image overall.

Moving to the next section of the triangle, we have Aperture. The aperture is essentially the eye lid of the camera lens. It controls the quantity of light we allow into the camera. The important thing to remember is that the higher the aperture number, the more pin-point or narrow the aperture will be, and the smaller the number, the wider or more open the aperture will be. So how might this have bearing on or fit the context of landscape photography you might ask? Well, when we take a look at camera settings for Astrophotography, we see that having a good understanding of aperture adjustments is crucial to having proper exposure of your image. When I was living in Alaska capturing the Northern Lights, I would typically run a lower aperture (starting with the lowest number possible for my given lenses) to let in as much light as possible. Although the aurora can throw off quite a bit of light, you will typically want to allow your camera to let in as much light as possible to counteract the dark nighttime skies. This is where you can now bring together the other section of the triangle we just looked at (Shutter Speed) to help use them in correlation with one another to achieve a desired outcome. Selecting a shutter speed between 1-14 seconds is typically a good place to start in conjunction with the wider aperture (starting around f/2.8 or lower if possible). If the aurora is moving quickly through the night sky, you may want to increase the shutter speed to retain more of the detail of the lights since they have a river-like effect and can move, expand, and bend in a way that is very similar to water. In controlling the diameter of the aperture, you gain control over the camera’s focus range, depth of field, and sharpness.

Finally, the last piece of the triangle is ISO. To give some meaning into this leg of the trifecta, the acronym stands for “International Organization for Standardization,” but keep in mind that ISO is not a reference to the many product and technology standards as it relates to photography. Starting at the base level, ISO is a setting within your camera that will allow you to brighten or darken your photos. When you increase your ISO number or value, your photos will get progressively brighter. It allows you as the shooter to be more flexible with your shutter speed and aperture settings and can allow you to capture images in darker climates and environments. But keep in mind, that increasing your ISO may introduce more grain into your image, which can reduce the sharpness of the image and at times render it unusable, especially for printing. There is essentially a bargain that takes place when you increase ISO. If you can no longer brighten your photo using shutter speed or aperture, then raise the ISO, but you will typically want to resort to those two, at least initially. Signal amplification is a synonymous way to describe what ISO allows you to adjust as a photographer within your image.

When using this tool, you are ultimately trying to achieve what we call optimal exposure. This is essentially where this “Photography Trinity” comes into play and allows you as the photographer to have the best control over your camera to achieve the result you are looking to creatively capture. As I said earlier, try to always have a vision for your images. How is the scene in front of you making you feel? What do you want to convey to the viewer? After you make this determination, then, with your understanding of this helpful tool, capture that moment you don’t want to slip away!

Below, I have created an illustration that I hope might assist and give you a visual to help put this tool into practice:

I hope that this information has been helpful and educational for you and given some greater clarity into what is taking place from a technical standpoint between your camera body, lens, and how using the exposure triangle, you can capture some compelling and beautiful shots.