Aperture for Beginners (7 Days to Mastering Manual Mode)

Understanding Aperture for Beginners

Welcome to Day 3 of Mastering Manual Mode!

Now that we have covered the important reasons why you should be learning to shoot in manual mode, and how to use your Light Meter, lets take a closer look the first of 3 important elements that make up the exposure triangle: Aperture - a crucial setting to understand and use properly if you want to take great photos.

What is Aperture?

Aperture is like the pupil of your eye. It can be opened up or closed down depending on how much light you want to enter the camera.

When you are in a low-light conditions you will probably want your aperture opened up as much as possible.  On the opposite end, when you encounter bright conditions you have the option to close the aperture down to let in less light.

What is an F-Stop and How Does it Relate to Aperture?

An F-stop is the number on your camera that tells how open or closed the aperture is.

The most confusing thing about aperture and F-stops (and one that you need to remember because it is a bit counter-intuitive) is the smaller the F-stop number, the larger the aperture opening is and the more light you are able to let in.  The larger the F-stop number the, the smaller the aperture opening is and the less light you are able to let in your camera.

In following infographic, you can see the 6 images I shot of the same subject with my aperture set on 6 different F-stop settings.  As you can see, the lower F-stops (wider aperture) let in more light than the higher F-stops (smaller aperture).

Aperture, F-stops and Depth of Field

Aperture not only lets in light, it is also one powerful way to control your depth of field.

Depth of field is quite simply the amount of your image that is in perfect focus between your camera and the farthest your eye can see.

In the real world, when our eyes survey a scene everything we see is in focus (unless your eyesight is terrible!)  This is not always the case in-camera! 

The smaller the F-stop/aperture the less depth of field you have.  That means that if I set my aperture to f/2.8 and focus on my subject, not much behind or in front of them will be in focus.  If I set my aperture to f/16 and focus on my subject much behind them and in front of them will be in focus.  

You can see this clearly demonstrated below.  Notice the change in the depth of field achieved at the 6 different F-stop/aperture settings.

How to Adjust Aperture on a Canon Camera

Make sure you are in Manual Mode prior to following these instructions below!

To set the aperture on your Canon Rebel series camera, depress the shutter release button until the meter is activated.  Then, using your thumb, hold in the Av button on the back of the camera and use your index finger to turn the Main dial right for a smaller aperture (larger f-stop number) or left for a larger aperture (smaller f-stop number).

To set the aperture on your Canon EOS series cameras, depress the shutter release button until the meter is activated.  Then, using your thumb, turn the large dial on the back of the camera.

How to Adjust Aperture on a Nikon Camera

To set the aperture on Nikon's entry level cameras, depress the shutter release button until the meter is activated.  Then, using your index finger, hold down the button with the little aperture circle next to it on the top of the camera and then use your thumb to turn the Main dial.

To set the aperture on Nikon's semi-pro or pro line cameras, depress the shutter release button until the meter is activated.  Then using your index finger, turn the sub-command dial on the front of the camera beneath the shutter release button.

Aperture Example #1

Lets say I want to take a portrait of my daughter and I want her to be in focus and the background to be blurred.  I would choose an open aperture (like f/2.8) and focus on her eyes.  She would be in focus but the background and any elements in front of her would be blurred.

Aperture Example #2

In this next example, I wanted to take a photo of the beautiful landscape and mountains in back of my house.  Because I want everything between myself and the mountains to be in focus I would choose a closed down aperture of f/16 or f/22 to ensure that ALL of the landscape details are in focus.

One Final Note on Aperture

You may find that you do not have access to all the F-stops mentioned above.  This is because your camera lens controls the lowest aperture you can access.  Your camera only controls the highest aperture you have available.

Don't miss tomorrow's tutorial on Shutter Speed - another biggie!

Congratulations! You've just completed Day 3 of Mastering Manual!

But Don't Stop Now!

Make sure to read the rest of our series to help you Master Manual Mode.  If you’ve missed any of the posts, you can read/review them at any time by clicking these links!