Understanding the Exposure Triangle

 

    The exposure triangle is a fundamental concept every photographer or videographer should understand. It refers to the three main camera settings that control the exposure of a photo - aperture, shutter speed, and ISO. By balancing these three settings, you can achieve proper exposure and capture the scene as you envision it.

1. Aperture is the size of the opening in the lens that allows light to pass through to the camera sensor. It is measured in f-stops like f/2.8, f/5.6, f/11, etc. A wider aperture (lower f-number like f/2.8) lets in more light and produces a shallower depth of field. A narrower aperture (higher f-number like f/11) lets in less light but provides a deeper depth of field.
2. Shutter speed is the length of time the camera shutter remains open to expose the sensor to light. It is typically measured in fractions of a second, like 1/250, 1/60, 1/2, etc. A faster shutter speed freezes motion but lets in less light. A slower shutter speed allows more light in but can introduce motion blur if the subject or camera moves.
3. ISO is the camera sensor or film sensitivity to light. A lower ISO number like 100 is less sensitive, producing the cleanest images. Higher ISO numbers like 3200 are more sensitive, allowing you to shoot in lower light, but introduce more digital noise (film grain if shooting film) into the image.

     The key is that these three settings work together to determine the overall exposure. If you adjust one, you'll need to compensate with the others to maintain the same exposure.    For example, if you want to use a faster shutter speed to freeze action, you'll need to balance that by either opening up your aperture to let in more light and/or increasing your ISO. If you want a deep depth of field using a narrow aperture, you'll need a slower shutter speed and/or higher ISO to get enough light.    Modern cameras and phone can automatically balance the exposure triangle through computation if you select an auto or semi-auto mode. In order to gain full creative control, it's best to shoot in manual mode so you can intentionally choose your aperture, shutter speed, and ISO for each shot. I hope you will try the simulator from Andersen Images below to get a better understanding.

http://www.andersenimages.com/tutorials/exposure-simulator/

Graphics obtained from Petapixel.com