What is exposure?
Exposure refers to how light or dark an image is. Your camera’s sensor records how much light hits it and then the image is created. A properly exposed image should accurately record the scene as it was. An underexposed image will be darker than the scene was, and an overexposed image will be brighter than the scene was.
What is the exposure triangle?
Exposure is made up of three elements – aperture, ISO, and shutter speed. Where these three elements meet is the exposure of your image.
This site contains affiliate links to products. We may receive a commission for purchases made through these links.
WINDOW Metaphor – iso, aperture, shutter speed
My favorite way to help illustrate this comes from Bryan Peterson’s book – Understanding Exposure. If you don’t already have this book in your library, you should!
He says to imagine that your camera is like a window, one with shutters that open and close.
The size of the window (opening) is your aperture. A large window (or aperture like f/1.8) will let in a lot of light. A small window (or aperture like f/22) will let in less light.
The amount of time the shutters are open will determine the shutter speed. Open and close them quickly and you will have a fast shutter speed and let in less light (like 1/1000). Leave the shutters open for a while and you’ll let in a lot more light (like 30 seconds).
Now he says to pretend you are wearing sunglasses in the room. The sunglasses will affect how sensitive your eyes are too the light. If you have on very dark glasses your eyes won’t be too sensitive (ISO 100) If your glasses are barely tinted (ISO 3000) your eyes will be much more sensitive to the light.
You can vary the amount of light in the room by changing any of the elements. Have a bigger window (larger aperture) well than you have more light. Have the shutters open longer (slower shutter)…more light. If you are wearing lightly tinted glasses (high ISO)….more light and vice versa.
When you are shooting in auto, the camera is choosing all three of these elements for you. If you are in a semi-auto mode like Aperture Priority you are choosing the aperture and the camera is choosing the other two elements. Full manual mode is when you are choosing all three elements yourself.
Hopefully, this post helped explain the exposure triangle. We will explore ISO, aperture and shutter speed more in-depth soon!
About the Author
Beth Mancuso is a portrait and landscape photographer based out of Minnesota. She has been in business as a portrait photographer for over ten years. She has spent the last six years working as an instructor and mentor. Her work has been featured by National Geographic, Huff Post, My Modern Met, Peta Pixel, and Lensbaby. Her work has been published in Click, Midwest Living, and Black and White Magazine. You can read more about her here. You can find a portfolio of her landscape work here. You can find here portrait work here.