The following video will explain the three functions of your camera that effect exposure – aperture, shutter speed, and ISO. Exposure is basically how bright or dark your image is. And your camera needs to know how to read the light that is shining in your frame. So these three things help you control that light.

  • Aperture (also known as f-stop or the iris) is how big the opening in a lens is.
  • Shutter speed is how fast the shutter (the thing blocking light from entering your camera) opens and closes.
  • ISO is the sensitivity of the digital sensor (or film stock in film cameras).

And each of these changes the brightness of your image.

Watch the video to dive deeper:

The following is an excerpt from the Photography Masterclass: Your Complete Guide to Photography. Along with understanding how exposure works, it also effects the look and feel of your photo. This can be explained with the exposure triangle.

This is the exposure triangle – visualized. Visualizing this with this diagram will hopefully engrain this idea in your head.

While all three of these can affect how bright or dark your image is, there are a few key things to remember:

  1. ISO – affects how clean vs grainy your image will be. A low ISO (100-800 or above depending on your camera) will have a very clean image. A high ISO (1600 or above, again depending on the camera because some cameras have clean images upwards of 6400 ISO) will result in a more grainy image.
  2. Shutter Speed – affects how much motion blur your photo has or how sharp it is. A faster shutter speed (1/100 of a second or faster) will be much sharper than a slower shutter speed (1/30 of a second or slower).
  3. Aperture – affects the depth of field in your photo. A wider aperture (f/1.4 – f/5.6) will have a shorter depth of field, and have a more blurry background, than a smaller aperture (f/16 – f/22).

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As you take photos, you need to balance the three points on the triangle to get the look you want. Maybe you want to get something with a shallow depth of field, and need your f-stop to be 1.4. But doing this will make your image really bright (due to the wider aperture), and you will have to speed up your shutter speed along with lowering your ISO. See image below for an example of using a very wide open aperture.

Or maybe you need a very fast shutter speed to catch a fast-moving subject (such as a butterfly). By speeding up your shutter speed, you are letting less light into your camera. Therefore, you need to change the ISO or aperture to let more light in. Maybe you don’t want a very shallow depth of field, so you might have to increase your ISO.

This is where you can get really creative with your photography. And if you can get a good grasp of the exposure triangle, you will be well on your way to taking great photos in the manual mode.

Phil & Sam