Depth of Field Explanation – And How To Control It

Depth of Field Explanation – And How To Control It

Hey everyone, If your question is how does aperture work you are in the right place. Because this post is my depth of field explanation. I will tell you about the most talked about topic in photography, Aperture. It is one part of the exposure triangle, the other two being shutter-speed and Iso. All photographers around the world love to play with it because it either adds depth to the Photo by blurring it or gets almost everything in focus. I will try to explain everything I know about it as simple as possible. So let’s get started.

How does Aperture Work:

To make it simple the aperture is a hole inside your lens that lets light through it to the sensor. I think the easiest way to understand it is when you compare it to your eyes since every lens in today’s cameras is build like one just not as good. 🙂 Light light shines into your cornea, on your camera, it would be the front part of your lens that gathers all the light then passes to into the iris of your eye. On your camera, it would be the aperture. You probably have noticed that when people walk into a dark room the iris inside your eyes becomes really big and gets smaller when people look into something bright. That is because the iris regulates the amount of light that gets through to the retina (on your camera that would be the sensor). It is the exact same way on a camera lens.

Depth of Field Explanation

When you open the aperture you will have more light and a brighter picture. When you close it you will have less light shining onto your sensor and so a darker picture. You can always try to compensate that with iso and shutter speed.


How to Use Aperture:

If you go into the Av (aperture priority) or M (manual) mode on your camera your aperture will be displayed in with an F in front like f7.1. To understand how to use aperture you must know,  that the larger the number the smaller the actual aperture. Which means f3.5 is wide and f22 is almost completely closed.


Quick Tips:

  • Wide aperture= a lot of light on the sensor (bright picture)
  • Small aperture= only a little bit of light on the sensor (dark picture).
  • Big number f22= almost closed aperture.
  • Small number f1.8= wide open aperture.
  • Wide aperture= shallow depth of field.
  • Almost closed aperture= wide depth of field.

Depth of Field Explanation

What is Depth of Field:

Every time you change your aperture you also change the depth of field. The depth of field describes the area of an image that is sharp. For example, a shallow depth of field means the point you focused on is sharp but the fore and background are blurry. A wide depth of field means that almost everything is in focus. When I started taking pictures I only used a small aperture because I wanted as much as possible sharp. 🙂 But later I realized that having only a certain point in the picture sharp creates way more depth to the image. So, what I want to say experiment a little around to know what you like. 🙂

Depth of Field Explanation

How to Use Depth of Field:

A wide aperture (f1.8) creates a shallow depth of field. An almost closed aperture creates a wide depth of field.

How to Find out the Maximum Aperture of your Lens:

When you look at the top of your lens (in my case the 18-55mm kit lens from canon), you will find a something like 1:3.5-5.6 This describes the maximal aperture of the lens in f stops first zoomed out (f3.5) and then fully zoomed in (f5.6).understanding camera aperture

Alright, this is it from me for my depth of field explanation. I hope you had fun reading it and learned what you wanted to learn 🙂 If you have any questions or opinions let me know in the comments. 🙂


Cheers Aaron.

4 thoughts on “Depth of Field Explanation – And How To Control It

  1. Dave M.

    This is a really good primer for someone like myself that knows nothing about cameras. I have always heard those terms but never knew what they meant. Now I know what depth of field means and how to read the aperture information on my camera!
    Thanks for providing this info for the beginners like me!

    1. Aaron

      Hey, Dave. I am more than glad that I was able to help you out with this. If you have any further questions let me know. 🙂

  2. Rbtlrdoftkyo

    I always just never mess with the aperture settings because I didn’t know what it was, lol. So glad I came across this article. Now I can take even better pictures and experiment more with what’s in-focus and out of focus, or should I say different depths of field? Great piece, and I’ve certainly gained some knowledge here!

    1. Aaron

      Rbtlrdoftkyo, I hope I spelled that right 😛 Awesome I glad I was able to help you out 🙂

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