Aperture is one of the three factors that create an exposure. Understanding the aperture settings makes getting to grips with taking an evenly exposed photo a lot easier.
Using different aperture also opens up more creative avenues through unique effects. This post will teach you what they are and how to use them to your advantage.
What Is Aperture?
The best way to understand the aperture definition is to think of it as the pupil of an eye. The wider it gets, the more light it lets in.
Together, the aperture settings, shutter speed, and ISO produce an exposure. The diameter of the aperture size changes, allowing more or less light onto the sensor. This depends on the situation and the scene being photographed
Creative uses of different aperture sizes and their consequences are tackled in Step 4. Put simply, when talking about light and exposure, wider aperture settings allow more light and narrower ones allow less. Aperture can be confusing. Some people will say a wide or narrow aperture, but others might say a large aperture. What is the difference? A wide aperture refers to the wide opening in the lens, where f/1.2-f/2.4 is being discussed.
A large aperture refers to the number of f/stop, where f/32 or f/22 is being discussed. A low aperture and wide aperture are the same things one talks about the size of the number and the other relates to the size of the opening.
How Is Aperture Measured and Changed?
Aperture size is measured using something called the f-stop scale. On your digital camera, you’ll see ‘f/’ followed by a number. This f-number denotes how wide the aperture is. The size affects the exposure and depth of field (also tackled below) of the final image.
What may seem confusing is that the lower the number, the wider the aperture. This means that your camera aperture settings will be wide open at a smaller f-stop number, like f/1.4 (maximum aperture).
At higher numbers, like f/16 or f/22, you’ll get a narrow aperture.
Why a low number for a high aperture? The answer is simple and mathematical, but first, you need to know the f-stop scale.
The most important thing to know about these numbers is this; as the numbers rise, the aperture settings decrease to half its size. Half meaning that it allows 50% less light through the lens.
This is because the numbers come from an equation used to work out the size of the aperture setting from the focal length. You’ll notice, on modern day cameras, that there are aperture settings in-between those listed above.
How Does Aperture Affect Exposure?
Before we talk about anything else, let’s look at the exposure triangle.
The change in aperture size correlates with exposure. The larger the aperture size, the more exposed the photo will be. The best way to demonstrate this is by taking a series of photos and keeping everything constant with the exception of the aperture.
All the images in the slideshow below were taken at ISO 200, 1/400 of a second and without a flash. Only the aperture size changes throughout.
A good way to see the changing size of the aperture is to look at the size of the out of focus white circle at the bottom left of the image. The main creative effect of aperture, however, isn’t exposure, but depth of field.