Exposure Triangle

The exposure triangle consists of shutter speed, aperture, and ISO. Shutter speed, aperture, and ISO work together to produce a photo that is properly exposed.

Shutter Speed

Shutter speed is how long the shutter stays open, meaning it’s the length of time for light to hit your camera sensor. The faster the shutter speed, the less light hits the sensor. The slower the shutter speed the more light hit the sensor. Shutter speed is measured in fractions of a second, numbers like 1/2s, 1/4s … 1/250s, 1/ 500s. Fast shutter speeds 1/250s, 1/500s can freeze action/fast moving subjects, for example race cars, birds, sporting events. Slow shutter speeds blurs movement from camera shake or a subject that is moving. Slower shutter speed numbers are 1/15s, 1/30s, 1/60s.


Aperture is the size of the lens opening, the amount of light that enters the camera lens. It is measured by f/stop for example f/16 is a small opening so you will get less light and f/4 is a big opening so you will get more light. So in your camera the numbers will go as follows 2, 2.8, 4.5, 5.0, 5.6, 8, 11, and 16. So generally the lower the f/stop the more light will enter the lens and the higher the f/stop the less light will enter the lens. The higher number is considered a lower number like 11, 16, 22 while a lower number like 2.8, 4, 4.5 is considered a higher number. The aperture controls the depth of field. Depth of field is the distance between the subject and the background or the distance between the subject and the foreground. Depth of field is the acceptable sharpness in the photo.

“Large aperture = Small f-number = Shallow (small) depth of field. Small aperture = Larger f-number = Deeper (larger) depth of field”

For example, using f/2 will give you a shallow depth of field and using f/16 will give you a deeper depth of field. Also, the closer you are to the subject the shallower depth of field and the further you are to the subject the deeper the depth of field.


ISO controls the amount of light the camera needs, the sensor’s sensitivity to light. On your camera ISO is displayed as 100, 200, 400, 800. The lower the number, the more light is needed. The higher the number, the less light is needed. Raising the ISO higher than 400 or 800 can increase the amount of noise in the image. Keeping your ISO a lower number like 100 or 200 will decrease the amount of noise in the image. Noise is visual distortion. It’s like grain or discoloration in a photo.



Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store