Photography 101: The Basics of Exposure

When I went to college way back in the day, we took photos exposed onto film. (Film!? Right, I know. I’m as old as the hills!) As I reminisce about those days, I can still smell the sulfurous fumes wafting through the photography lab. While film has a special place in my heart thankfully, you don’t have to kill as many brain cells smelling that stuff as I did. Now we have digital, but many of the tried and true principles still apply whether you’re photographing on film or not. 

Today we’ll dive into the basics of exposure. Since knowing how to control the light is critical to great photography. And capturing the details of an image will save you time and energy when retouching. Not to mention, if you don’t have good exposure to begin with no matter what you do, you still may not be able to salvage an image. As the saying goes, when you put crap in, you get crap out.

 

It’s all about exposure.

Exposure is the amount of light (or luminance) that reaches your camera’s sensor or film x time. (Exposure == time x luminance). The time part of the equation is the length of time the light falls onto the film or sensor. By mastering exposure, you’ll capture the depth of an image from highlights, mid-tones, and shadows. There are three parts to exposure — shutter speed, aperture, and ISO.

Shutter Speed

Shutter speed is the amount of time your camera’s shutter takes to take a photo. On an SLR (Single Lens Reflex) camera, you’ll see numbers like 1/125 or 1/10. The bigger the number on the bottom, the faster the shutter moves, and the smaller the number, the slower it moves. 

So why do you need the different speeds? If you’re photographing a sports event, you’ll want to set a faster shutter speed so you can capture the fast-moving action and so the players don’t blur by letting in less light. With a slower shutter speed, you can blur motion and let in large amounts of light. Think of those calming waterfall photos where the water looks all creamy. That’s a slow shutter speed. Or another example is star trails where you see the spin of the earth and the route of the stars.

Shutter Speed Example

The image above taken in low light and flash wasn’t an option since it’s distracting to the dancers. Captured on a Nikon D90 SLR with a 3200 ISO with a shutter speed of 1/100 and at f5.0 at a focal length of 58.00. You can tell the image has a high ISO due to the “graininess”. The lens, a Nikkor 18–105mm has an aperture range of f/3.5 to f/22. If you are serious about sports and action photography invest in a good lens, the faster ones open up to f1.8 and will allow you to capture all the action. I was lucky to get the dancer in a moment when she paused, it’s recommended to shoot at 1/1000 for most sports.

How to Create a Long Exposure on Your iPhone
Long Exposure

This waterfall in Spearfish, South Dakota was taken as a “Live” image on my iPhone XR. To get the best image use a tripod for your phone. If you swipe up after you’ve take a “live” photo it will give you some effects options. To achieve this look I chose the “long exposure” option to create that creamy water motion blur effect. Learn more at the iPhone photography school here.

Aperture

The aperture of a camera is similar to the pupil of your eye. Set your aperture to f2, and it’s large and lets in lots of light (like a dilated eye); conversely, set it at f16 or f22, and it lets in less light. Have you ever tried that trick where when you forget your glasses and can’t see? You know the one where you make a tiny hole and curl in your forefinger and look through it, and what you’re looking at comes into focus? Same concept. It’s also important to note that apertures are fractions, so 1/2 (f2) is bigger than f16 (1/16).

My favorite thing about aperture is controlling the the depth of field  (but we’ll explore that more in-depth at a later date). Depth of field control is how you get the blurry background effect. You use a lower f-stop such as f5.6 or lower. Or use your portrait mode on your iPhone. Portrait mode isn’t just for portraits though, you can use it to achieve that blurred background effect for closeups too, like on flowers, or product photography.

Rocky Mountain National Park, 2021

If you have a newer iPhone you most likely have portrait mode. But did you know you can adjust the f-stop setting? The video above shows you how to get that blurry background in just a few clicks. Plus how to use the studio lighting setting as well.

ISO

In this instance, we’ll talk about ISO as it pertains to SLR cameras since the manual control isn’t available on your phone’s camera unless you download an app. (Learn more about your iPhone’s ISO and how to hack it here.) A little trivia tidbit ISO stands for “International Standards Organization.” ISO settings brighten or darken your photos. As you increase the number, the brighter the images get.

Before digital, you could buy different speeds of film, 100, 200, 400. And then “push” the film to higher speeds, for sports in college, I’d shoot at 1600 or 3200. When the number goes higher, the graininess or the “noise” of an image goes up, so there is a trade-off. Want to learn more about ISO? Read this article.

 The best way to master exposure is to get out there and practice. Now that it’s spring, get outside and start photographing. I’d love to see your photos, tag me on Instagram @themoonshinedesign and I’llcheer you along on your journey as a photographer.

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