Depth Of Field: Changing Aperture – Photography Experiments

Photo Experiment 3, y'allToday we start a mini-series inside the larger 40 Photography Experiments series. Today, tomorrow, the next and the next, we will be focusing (har!) on Depth Of Field and the effects it has on images.

Depth of Field

Let’s start with a simple exercise to help get the “Ah ha!” moments going. Take a look at these two images below and think about which one you like more.

Do you notice the difference? One has a shallow depth of field (not a lot of things in focus) and the other has a large depth of field (all kinds of things in focus). Both produce different effects and both can tell a different story. So what did I change between the images?

The answer is Aperture. The main difference between the two shots is the aperture setting on my camera. I shot in Aperture Priority Mode and while my shutter speed did change, it did not result in any clear effect in the image. My ISO, focus point and framing remained the same.

As described in my post on Aperture, changing your aperture will change your depth of field and give your images a different look. Here then, is an experiment for you to run on your own to see the effect firsthand.

Here’s the experiment you can run:

Depth of field experiment of magic
An idyllic, tropical island paradise amongst the San Blas Islands of Panama sits in beautiful, turquoise waters of the Caribbean Sea

1.  Set up a scene on a table or find something in your surroundings that duplicates the distances listed below.

  • Set your camera on a steady object or ensure it stays in the same spot for this experiment. A tripod would be helpful.
  • Place an object 2’/.6m in front of your camera.
  • Set another object 2’/.6m beyond that object.
  • Set one last object 4’/1.2m beyond the second object. These measurements need not be exact.

2.  Change your camera to Aperture Priority (it’s the little A or Av item on the control dial, likely on top).

3.  Zoom in to 50mm or as close as you can get to that focal length. If you are using a point and shoot, zoom in half way from the nearest to the farthest zooms.

4.  Focus on the first object but keep the other two objects in the field of view. Move the objects side to side as needed, but try not to move them front to back.

5.  Lock the focus of your camera by changing it to manual. This helps your camera to not pick a new focus point during this experiment which can ruin things.

6.  Set your ISO to 400 for a middle of the road setting. This is not critical to the experiment.

7.  Set the aperture to the smallest number it can achieve. This is usually done by spinning one of the control wheels on your camera. Your lowest aperture may be f/2.8 or f/4 or f/5.6. It’s not too important right now what this number is.

8.  Take a photo.

9.  Turn the control wheel you just used, three clicks higher. This will change your aperture from something like f/4 to f/5.6. Each click on the control wheel is 1/3 of a stop, so three clicks is one full stop. Ensure you’re going the right way and that your aperture number is getting larger. That’s the goal.

10.  Take another photo.

11.  Change your aperture again as per #9. Another three clicks = one stop. If you were at f/5.6 before, now you’re at f/8.

The Algodones Dunes extend to the horizon where they meet the Chocolat Mountains

12.  Take another photo.

13.  Continue this process until you can’t go any higher with the aperture setting. Some point and shoot cameras top out at f/8. Other cameras will continue on to f/29 or so.

You’re done!

Take a look at the images on your computer (or the back of your camera screen with the zoom feature if you’re impatient). What has changed as the aperture number went up?

My images up top were shot at f/2.8 (first) and f/22 (second). Did you get the same results?

Changing your aperture setting can result in more and less depth of field. This can make objects stand out (portraits) or make sure everything is in focus (cityscape or mountain vista).

Play around with these settings some more. Walk around your house, the office, the street and take the same exact same photo twice, only changing your aperture, and see which way you like the results. There is no right or wrong, there is only your preferred result.

Tomorrow we will build on the Depth Of Field concept by changing focus points.

Questions?  Pop ’em like Pez in the comments section below. or email me at

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

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