Beginners Guide To Aperture

What is Aperture?

Aperture is the size of the opening in your camera's lens that lets light in. Think of it like the pupil in your eye - it gets bigger to let in more light when it's dark and smaller to let in less light when it's bright.

Aperture is measured in f-numbers or f-stops, like f/2.8, f/5.6, or f/16. The smaller the f-number, the bigger the opening (and vice versa).

Aperture controls two important things in your photos:

1. Brightness (Exposure): A wide aperture (e.g., f/2.8) lets in more light, making your photo brighter. A narrow aperture (e.g., f/16) lets in less light, making your photo darker.

   
   

   

   
   

2. Depth of Field: Aperture affects how much of your image is in focus. A wide aperture creates a shallow depth of field, while a narrow aperture promotes a deep depth of field.

   
   

What is Depth of Field?

Depth of field (DOF) refers to how much of your photo is in sharp focus from front to back. It’s the area between the nearest and farthest parts of your image that appear acceptably sharp.

• Shallow depth of field means only a small part of the image is in focus, and everything else is blurred. This is great for portraits or wildlife when you want to make your subject stand out from the background.

• Deep depth of field means most or all of the image is in focus, from the foreground to the background. This is ideal for landscapes or scenes where you want everything sharp.

What Affects Depth of Field?

Three main things control your depth of field:

1. Aperture - This is the opening in your lens, measured in f-numbers like f/2.8, f/5.6, or f/11.

   • A wide aperture (like f/2.8) gives a shallow depth of field.

   • A narrow aperture (like f/11 or f/16) gives a deeper depth of field.

2. Distance to Your Subject - The closer you are to your subject, the shallower your depth of field becomes.If you step back, more of the scene will be in focus.

3. Focal Length of Your Lens - Longer lenses (like 200mm) tend to have a shallower depth of field than wide-angle lenses (like 24mm), especially when shooting at the same aperture.

   
   

The image on the left has a deep depth of field at f22, while the one on the right has a shallow depth of field at f4. Note the difference in sharpness and detail in the background.

Why Does It Matter?

Understanding depth of field helps you control the story you tell with your photos.

• Want to blur out a messy background? Use a shallow DOF.

• Want everything in a sweeping landscape to be sharp? Use a deep DOF.

It’s one of the most creative tools a photographer has—once you get the hang of it, you can use it to guide the viewer’s eye exactly where you want.

A shallow depth of field is generally desirable for bird photography, creating soft and creamy backgrounds that help to keep the bird front and centre and not distract the viewer with too much detail in the background.

Pro Tip for Beginners! When experimenting with aperture, start with Aperture Priority mode (A or Av on your camera). You choose the aperture, and the camera adjusts other settings for the correct exposure. This helps you focus on learning how aperture affects your photos.

Shooting at a wide aperture (lower number) creates a soft blur to the background, perfect to prioritise one subject over another within the frame.

Field Exercises for Beginners: Exploring Aperture in Action

Objective: Help beginner photographers understand how aperture affects their photos by experimenting with depth of field and brightness in a hands-on way.

Step 1: Prepare Your Camera and Subject

1. Set your camera to Aperture Priority Mode (A or Av).

2. Use a lens with adjustable aperture (most lenses have an adjustable aperture but check before you head out).

3. Find a well-lit spot with a fixed non-moving subject (like a flower, tree or an object). Ensure there’s some distance between the subject and the background.

   
   

Step 2: Start Wide (Shallow Depth of Field)

1. Set your aperture to the lowest f-number (e.g., f/2.8).

2. Focus on the subject.

3. Take a photo and notice:

   • The subject is sharp, and the background is blurry.

   • The photo is brighter because a lot of light enters the camera.

     
     

Step 3: Go Mid-Range (Balanced Depth of Field)

1. Change your aperture to a mid-range value (e.g., f/8).

2. Keep your focus on the same subject.

3. Take another photo and notice:

   • The subject is still sharp, but the background is less blurry and more detailed.

   • The photo may be slightly darker than the first one.

     
     

Step 4: Go Narrow (Deep Depth of Field)

1. Adjust your aperture to a high f-number (e.g., f/16).

2. Take the final photo, focusing on the same subject.

3. Notice:

   • Both the subject and the background are in focus.

   • The photo is darker because less light is entering the lens.

     
     

Step 5: Review Your Results

1. Look at your three photos side by side.

2. Compare:

   • Background blur: How does it change as you move from f/2.8 to f/16?

   • Brightness: How does the light change with each aperture setting?

Step 6: Practice with Variations

1. Repeat the exercise with a moving subject (e.g.a car driving past or a bird if you're up for the challenge!).

2. Try it in different lighting conditions, like morning or evening.

Pro Tip for Beginners: If your photos are too dark or bright, adjust the ISO or shutter speed to compensate while keeping the aperture consistent.

Aperture and Bird Photography for Beginners

Aperture settings play a crucial role in bird photography, particularly when it comes to achieving sharp focus and that beautiful background blur that we all want!

A wide aperture (like f/2.8 or f/4) allows more light in, which is especially helpful in low-light conditions such as early mornings or under a forest canopy - very common situations for bird photographers! A wide aperture also creates a shallow depth of field, isolating the bird from distracting backgrounds and drawing the viewer’s eye directly to the subject, and provided there is enough distance between the subject and the background, it helps to get those creamy backgrounds.

However, using a wide aperture comes with trade-offs. While it enhances background blur (bokeh), it also reduces the depth of field, which can be challenging when photographing birds with long beaks or outstretched wings. If the depth of field is too shallow, parts of the bird may fall out of focus, particularly when shooting close up or with telephoto lenses. In these cases, stopping down to f/5.6 or f/8 can provide a more balanced result, keeping the bird’s entire body sharp while still achieving some background separation.

Having said that, it isn't always essential the whole bird is sharp - as long as the eye is nice and sharp you can get away with the rest of the bird not being in perfect focus - but many would disagree with me on this! It depends on your style and whether you are seeking technical perfection or creative flexibility. Ideally a balance of both is the happy medium, but it's OK to push the creative limits provided it fits in with the story - for example, a bird in take-off mode with slightly blurred wings.

Aperture also interacts with other exposure settings like shutter speed and ISO. In bird photography, freezing fast movement—whether it's a wingbeat or a quick hop—often takes priority. Using a slightly wider aperture helps keep shutter speeds high without pushing ISO too far, which helps reduce noise. Understanding how to use aperture creatively and technically gives bird photographers more control over both the artistic feel and the technical sharpness of their images.