Aperture

Filmmaker's Dictionary Feb 22, 2021

What is aperture?

Aperture is one of the three key elements of capturing perfectly exposed images. It’s the opening of your lens, also called a diaphragm. It influences how much light is allowed to hit the image sensor, affecting the overall brightness of the picture.

The smaller the aperture, the less light is allowed in – similar to human pupils. This means that generally speaking, well-lit scenes require small or narrow apertures, while dark, poor lighting conditions usually need large or wide ones.

Aperture also adds dimension to photos by controlling the depth of field. Large aperture openings also help achieve a shallow depth of field. Creating soft and blurry backgrounds, or bokeh to separate the subject is easy with wide apertures. They also help focus the viewer’s attention.

How is aperture measured?

Aperture is measured on the f-stop or f-number scale. This scale might seem confusing initially, but it’s simple to use. This scale consists of f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22.

As the numbers rise, the aperture of a lens decreases to half the size at every stop.

This means that if we change our aperture from f/4 to f/5.6, 50% less light hits the sensor.

If we go from f/11 to f/5.6, the lens is now letting in four times the original light.

The reason why a higher f-stop number correlates to smaller apertures is due to the mathematical calculation behind it.

How to pick the right aperture

Lenses have different maximum apertures, and these can very much impact usability and price. To take the best images and choose the best lens for you, you need to understand what situations specific apertures are suited for.

Apertures as big as f/1.4 and f/2 are amazing in low light situations and creating bokeh, but they’re usually only supported by prime lenses and those tend to be expensive.

With an f-stop of f/2.8, cameras are still able to take sharp images in dark conditions. These are frequently used for outside portraits for a good definition of facial features.

F/4 is the best choice for portraits in fair conditions. It allows for capturing a lot of detail and helps keep the subject in focus.

F/5.6 and f/8 struggle with poorly lit scenes, but they’re increasingly better for group photography, ensuring that the deep depth of field keeps everyone in focus.

At an aperture of f/11, your lens is at its sharpest. These and f/16, f/22 openings are great for landscape photography with more and more noticeable detail in the whole frame. Deep focus is achieved using the smallest apertures.

Summary

Now you have might have a better overview of what aperture is and how it influences photos. However, they are not the only thing affecting your images. You can learn more about camera lenses on photographylife.com, which also have great impact on the final outcome.

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