The Exposure Triangle

Today’s post is on the “Exposure Triangle.”

You’ll find this everywhere on the Internet. A quick Google search turned up 18,300,000 results!

What is the exposure triangle? It’s basically the combination of the three factors that affect your exposure- ISO, shutter speed, and aperture. I put a pic on the Intro to Photography page with the rest of this article.

Remembering it is easy if think of a triangle and visualize that changing as you change your settings. That’s pretty much the gist of it.

Here’s a list as an example. Use that list to visualize your triangle and you’ll be off to the races, at least for the moment. I’ll use whole stops for simplicity. Each stop is either double or half the amount of light compared to the two numbers next to it.

ISO                                    APERTURE                SHUTTER SPEED
100                                           f/4                                  1/1600
                                                 f/5.6                               1/800
                                                 f/8                                  1/400
                                                 f/11                                1/200
                                                 f/16                                1/100

Looking at the first triangle 1/1600, f/4, at ISO 100, you can see that any changes require a change to another side to remain the same. I can change the exposure to 1/800, f/5.6, at ISO 100 and get the same exposure. Cool, huh?

Let’s try something else. This one will demonstrate the importance of the triangle and knowing how it works. At ISO 200, f/8, 1/400, my image is overexposed. How can I fix it? Try ISO 100, f/8, 1/400. That’s half the previous exposure level!

The first example showing how to get the same exposure is useful to figure out how much DOF you want and to help you keep your exposure constant in constant lighting.

The second example gives you an idea of how to use this tool to get more of your shots usable in changing lighting.

For the rest of this, visit our Intro to Photography page, and do a web search on it. Don't worry, though, more about exposure will be coming around soon!

Focal length will be our next topic.

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Enjoy the rest of your week!