Tuesday Assignment #1 – The Effects Of Aperture Adjustment On Depth Of Field – 31+ Days To Better Photography

As promised, it’s time to add some assignments to the 31+ Days To Better Photography. I’ve been yappering on about how to do things for a while and thought it best I give some concrete assignments to those who need to see for themselves. Unlike the weekend challenges I have been posting (and will continue to post), these assignments are meant to guide you through the how and why to shoot examples, so you can apply the rule to your own photography. The weekend challenges are more about experimenting with a topic and concept. In this case I might have put the cart before the horse for some readers and I want to change that.

The first assignment is simple. They’ll get more complex (maybe) but for now, let’s start with one of the basics; Aperture and how it relates to Depth Of Field.

First, switch your camera to Aperture mode. This will be listed as A or Av on the control dial (even a lot of point and shoot cameras have this mode). In this mode you will pick your aperture and the camera will decide your shutter speed (and ISO if you have not set it. And don’t worry if you haven’t, it’s not very important for this assignment).

Next, you will need some props:

  • Table
  • Camera
  • Organic Tasty-Yummy-Os Cereal Box
  • Can of Motoroil (yes, I want you to find the old style cans. Go back to the 1950s if you have to.)
  • Bunny

If you can’t find these exact items, don’t sweat it. Just get two objects of decent size. The bunny is there to make you smile.

Now, set up the table as shown here:

Place your camera in one spot and don’t let it move. If you have children, now is not a good time for them to be running around you. This is what the bunny is also for. Give them the bunny and let them play outside.

If you don’t have a ruler, don’t sweat it. Grab a piece of paper that is Letter/A4 size. Measure one and a half of the long lengths = about 18″/.45m (close enough for this assignment). One length is close to 12″/.3m.

Move the first object and the second object until each fills half the screen or viewfinder on the camera. Make sure the overall distances don’t change as you move things around.

Zoom your lens to 50mm or as close as you can to that setting. For those with point and shoots with no focal length guide, zoom until the objects look about the same size on the screen as they do in real life.

Now comes the assignment. And you won’t see my pictures on here. Why? Because I want you to see first hand what happens. I’ll explain what should happen if you’ve done it right. It’s highly likely you will do everything right.

  1. Adjust your camera, while still in Aperture Priority Mode, to the lowest number you can achieve. This will likely involve a dial. Read your manual if you are confused. For a lot of you this number will be f/4, f/5.6, f/3.5 and for some, f/1.8 or f/2.8. The exact number isn’t super important right now. Just get the lowest number you can.
  2. Focus on the Organic Tasty-Yummy-Os box and hold it there. Switch to Manual Focus mode if need be. Again, your manual is your friend. Don’t change your focus for this entire assignment.
  3. Take a photo. <CLICK>
  4. Now, WITHOUT MOVING ANYTHING (no matter how hungry you are for the Os), change your Aperture setting to f/11. You may notice, if you are viewing through the viewfinder, you don’t see the f/ part, just 11. That’s ok.
  5. Take a photo. <CLICK>
  6. Lastly, change your Aperture setting to the highest number your camera can achieve. Some will notice f/22 or f/29 or more. For those with certain point and shoots, you might not be able to go above f/8 and that’s just a limit of the camera. This assignment won’t be all that fun for you. Sorry.
  7. Take a photo. <CLICK>

Now review your photos. What has changed? Your focus was locked. Your camera didn’t move. The objects didn’t move (unless you put the bunny in the scene). So what changed?

What you’re are looking at is a change in your Depth Of Field. Depth Of Field is that range where things are in focus and it grows as your aperture number grows (which corresponds to a smaller aperture. You DID read the Aperture post, right?). From the widest aperture (smallest number) to the middle to the smallest aperture (biggest number) the motor oil should have come more and more into focus.

This is one way to control the focal point in a shot. With a small aperture (big number) a lot of things are in focus and the shot is often boring. With a wide aperture (small number) only a few things are in focus and standout from the background because of that.

Make sense? If not, ask questions below.

If you want a head start on next week’s assignment, you can experiment with moving closer and further and repeating the assignment. I’ll get into that aspect of depth of field next week, but feel free to play!

31 Days To Better Photography is a series written by professional photographer Peter West Carey on The Carey Adventures.Com. The series is designed to unravel the mysteries of photography so you can take better pictures. Subscribe here to receive all the updates, and bonus material, all month long. Your comments are always welcome.

One Reply to “Tuesday Assignment #1 – The Effects Of Aperture Adjustment On Depth Of Field – 31+ Days To Better Photography”

  1. monstermum

    Yippee! I came, I saw, I conquered! Thank you for the lesson. Something “clicked” in my brain and things have become “more in focus”.
    I didn’t have motor oil so I did the stereotype Canadian thing and used my empty maple syrup bottles…and the bunny is taboo here in Australia so I counted on a magpie to make me smile ;<)
    Thanks, again, for this posted lesson.


Leave a Reply