Understanding Aperture, Shutter-Speed and ISO: The Exposure Triangle

These three technical aspects of photography are called the Exposure Triangle. Understanding each element and how it affects your images is crucial, and furthermore understanding how they work together and can affect your image is even more important. Let’s take a look.


  • This is how open or closed the “eye” of the lens is.
  • Wider aperture = Lower F number =  Greater Depth of Field (More of image in focus, backgrounds sharper)
  • Narrow aperture = Higher F number = Shallower Depth of Field (Less of your image in focus, backgrounds blurred, Bokeh)
  • Shoot the same image with different apertures and not how the sharpness and depth of field changes. 🙂

Shutter Speed:

  • This is how long the shutter remains open.
  • Longer Shutter = More Light/Brighter Image = Blurred Action = More Time for Sensor to Gather Light = Higher Exposure
  • Shorter Shutter = Less Light/Darker Image = Fast Moving Objects Freeze = Stop Motion = Sports/Action Photography
  • This is probably the MOST important of the 3 exposure triangle settings. You need to make sure that it’s set appropriately for what you are trying to capture. So experiment with this.


  • This is the sensitivity of the Image Sensor
  • Higher Sensitivity = Brighter Image = More Noise/Grain
  • Lower Sensitivity = Darker Image = Less Noise/Grain
  • You should change your ISO depending on the time of day or the light available in your environment.
  • Shoot at lower ISO’s if possible, but raise it if you are in a church, concert, etc.
  • Examine your images, if there is too much noise then sacrifice some brightness for clarity.
  • Sometimes high noise can be corrected in post (LightRoom / PhotoShop)


The key ingredients are Aperture, Shutter Speed and ISO, but how you cook them is up to you. Play around with the settings and you’ll notice that actually have good flexibility with your image and the only real limiting factor becomes noise and you need to decide which is a higher priority for you, clarity or proper exposure. And even then, you can post process the image and correct it.