Aperture?

Put simply, aperture is ‘the opening of the lens.'

When you hit the shutter release button on your camera a hole opens up that allows your camera’s image sensor to catch a glimpse of the scene you’re capturing. The aperture you set impacts the size of that hole.

Tip - The larger the hole the more light that gets in – the smaller the hole the less light.

What you will learn:

1. Use depth of field with an SLR or bridge camera

2. Use your phone to take depth-of-field photographs

QUICK ACTIVITY

Let’s play with our phones.

Watch this TikTok video.

Place three objects equal distance apart and use your phone to focus on each object. Take three images of each object. Let’s see what you get!

WHAT DO YOU KNOW ABOUT THE DEPTH OF FIELD?

Depth of field is the zone of acceptable sharpness in a focused photo.

When capturing an image that represents this technique, you should consider these three points:

1. Aperture (F-stop)

2. Distance from the subject to the camera

3. The focal length of your camera's lens

The f-stops used for depth of field begin at F-stop 5.6 or below. The wider the aperture or the larger the hole that lets light into the camera, the blurry background is visible in each image.

In every picture, there is depth of field and this is what you need to remember as depth of field works in terms of distance from the camera, just like our eyes.

Whenever you see something, you always see the first or closest object to what you are looking at; this is what the camera will do, focusing on the closest item to what you are looking at. You need to remember this and then when you change the aperture the area of focus changes. The further away items fall off and become out of focus.

Understanding narrow & large depth of field

• Narrow Depth of Field — Only a small part of the image is in sharp focus. In a narrow or small DoF, you focus only on the subject, while the background is blurred. Used for flowers, objects & portraits. This is below f5.6

• Large Depth of Field — More of the image is in sharp focus. A large DoF focuses more on the entire frame and has a wider angle. It has a much sharper focus on the entire image, rather than just a small part. Used for landscapes. Above f5.6.

Distance from the subject to the camera

Depth of field works better when you consider distance. This can begin by considering the focus of the photograph. The focal length, and your proximity to what you are photographing, will help blur the picture.

If you are shooting natural bokeh or bokeh images or anything else, you need to distance yourself from the object. This is often the case when using a kit lens, with an aperture limit of only F5.6. Most of the time when you look through the viewfinder you can see if you have a blurry background or not. If not, amend the aperture or move further away.

ACTIVITY 1

Hold your camera and set it at either F4.0, or lower than F5.6 & take three images at three different focal lengths.

So shot at 55m, 28m & 18m

Question: Do you see any difference in the background?

Aperture & Focal Length

Do you know the difference between a wide-angle and a telephoto lens?

• Telephoto lenses - these zoom into the view (telephoto is 50 m and higher).

• Wide-angle lens - this zooms away from view (Wide-angle is 28 mm and lower)

Different focal lengths per lens will affect the depth of field when taking a photograph, so it is helpful to understand the difference between these two types of lenses.

Key points to remember - as you move closer to your subject with your aperture at the same point your background will be blurry.

By playing with your lens, you will find the answer to the questions above, as the focal length changes the aperture.

Question 1 answer: the aperture changes as you zoom your lens because the lens does not physically support the widest (smallest number) aperture at all focal lengths of the lens. 

The key points to remember are:

1. As the focal length value decreases, the lens becomes a wide-angle lens, and as the value increases, it becomes a telephoto lens.

2. In our eyes, we see 50 ml. (on a full-frame camera)

By understanding the question asked above and the effects on what you see through the camera as you change the focal length you will be able to visually understand how to create depth of field.

Summary

This blog is a tool to help you understand how these three elements work together to ensure a wonderful depth-of-field image.

1. Aperture (F-stop)

2. Distance from the subject to the camera

3. The focal length of your camera's lens

You need to consider all three for this process or technique to be effective.

ACTIVITY 2

Try these techniques:

• Go around your home and garden

• Look for objects to use. Always try three objects at different distances apart.

• Play with the moving nature

• Capture the sun rays through the trees as a background (natural bokeh).

• Look at the repetitive areas in your home

• Here are some examples that I have done throughout my home and garden.

Aperture Priority or Manual Key settings and actions to help with this activity

1. Shot at f5.6 or lower

2. If you can only shoot at f5.6 you will need at least 2m between the object and the background for the blurred background.

3. Use a tripod if you plan on shooting at a shutter speed lower than 1/60 sec.

4. If you combine this with a macro lens, I recommend a tripod.

5. Shoot at auto or 400 ISO. If you have more confidence in ISO, you can shoot at 100 and use a tripod if your shutter speed drops below 1/60 sec.

6. The appropriate white balance for the type of light should be set to auto or at the appropriate setting.

My next blog will be a further instalment on using what you have learned here and practising the Bokeh technique.

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