Photography Basics: Aperture, Focal Length, Distortion, and Compression

In this tutorial, I am going to walk you through some of the basic elements of photography.

When you grab a camera to take a picture, there are several basic factors that you need to be aware of in order to get the most out of the device in your hands.

The exposure triangle is a tool that is often used to explain the different settings that will control exposure. Shutter Speed, ISO, and Aperture all impact how much light reaches the sensor, and ignoring any of the 3 will lead to missed shots and you will likely not be happy with the results. This tutorial will primarily be understanding aperture, and its relation to focal length.

Let’s begin with focal length. As you can see in the .GIF below, shorter lenses allow more elements to fit into the frame of the picture, while longer lenses narrow your field of view. This makes smaller things look larger in the frame. Having a wide variety of focal lengths available to you will give you versatility when you cannot get very close to your subject, or when you want to include a vast landscape in the shot. However, for in the making of this .GIF, I used 8 different lenses(see below), valuing thousands of dollars. Most of them were prime lenses, and many people will prioritize the versatility of zoom lenses over the image quality of primes.  [all images shot at f/2.8 and varying shutter speeds and ISO’s]

focallength-tiny
[click to view] – Media by Stephen Hillrich
Next, I would like to introduce the element of aperture. This next .GIF represents a series of images being taken an a focal length of 50mm, with varying apertures. Aperture measures the size of the opening that light travels through to hit the sensor, but the point here is to represent that the more “open” your aperture is, the narrower your depth of field is.  As you can see, a narrower depth of field leads to less of the image being in focus. Therefore, a shot at f/1.2 will absolutely blow out the background behind the subject of a portrait, while a shot at f/16 will keep more of the definition of background elements. In this case, the trees are more visible the narrower the aperture.

aperture-tiny
[click to view] – Media by Stephen Hillrich
The last aspect that I would like to bring up is the relationship between distortion and compression. I have chosen to demonstrate this with… surprise… another .GIF!  This .GIF represents a series of images all taken with the same aperture (f/2.8) and roughly the same framing (subject size), but at varying focal lengths.  The interesting thing here is that for the image at 14mm, I was about 3 inches from his face, while the shot at 600mm required me to be over 30 ft away from the subject to get a similar framing.

You may also observe that even though the aperture remains the same, the field of view (meaning, the amount of the image in focus) gets narrower, meaning the background gets softer as we zoom further.

[click to view] - Media by Stephen Hillrich
[click to view] – Media by Stephen Hillrich
We usually encounter distortion the most in wider focal lengths (ex: 14, 20, 24, 28, 35…), and compression is most evident in longer focal lengths. As you can see in this .GIF, the wider focal lengths tend to make the subject’s face look unnatural. His nose is larger than normal, and other features are also shrunk or otherwise distorted. The overall face shape is much narrower. This is distortion, and as we use longer focal lengths, we see that his face widens out to what we are more comfortable seeing.

Compression is related, but slightly different. As you can see in the wider shots, the background includes many more trees and leaves and elements of what is behind the subject. Even though we used the same aperture of 2.8 at both 24mm and 200mm, the shot at 24mm includes a lot more in the frame. The shot at 200mm compresses everything behind the subject.  If you are not seeing it right away, just try to focus on one single tree and how it gets larger as we zoom in further.  This is most notable between 14-28mm.

**Please note that the longest zoom lens does not have an aperture range that goes all the way to f/2.8. That means that the shot at 350mm had an aperture of f/6.0, and the shot at 600mm was at f/6.3. See how narrow the field of view is though, because of the greater focal length.

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Shout out to WordPress for limiting media uploads to 2mb, so I’m sorry about the poor quality .GIFs

I hope you have enjoyed this tutorial! The best way to learn any of this is to grab a camera and go outside and play with it! Happy shooting!

If you are interested in the gear used, here is a list.

Nikon D700

Rokinon 14mm f/2.8

Nikon 24mm f/1.8

Nikon 28mm f/1.8

Nikon 35mm f/1.8

Nikon 50mm f/1.2

Nikon 50mm f/1.8

Sigma 50mm f/1.4

Nikon 85mm f/1.8

Nikon 80-200mm f/2.8

Tamron 150-600mm f/5-6.3

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