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What Is Aperture in a Camera?

what is aperture in a camera featured image

Aperture can be one of the most confusing things about using a DSLR camera. It is also one of the controls within the camera that can give you some amazing results with your photos. So what is aperture in a camera?

What Is Aperture in a Camera?

what is aperture in a camera - a digital rendering of the the aperture opening in a lens
The Aperture opening in a camera lens

Quite simply, Aperture is the adjustable hole in a lens that lets the light through to your camera’s sensor. If the hole is small, less light will get in. If the hole is large, more light will get in. However, this has more than just the effect of making your photo brighter or darker.

Aperture also affects what is called Depth Of Field (DOF), which determines how much of your image will be in focus. We’ll look into this later.

How Is Aperture Measured?

Aperture is measured in what is called f stops. For example, an AF-S Nikkor 18-55mm lens has an aperture range of f3.5 to f22. The confusing thing about this is that a small f stop number such as f1.8 means a larger aperture opening, and a large f stop number like f22 means the opening will be smaller.

image of camera apertures and their corresponding f stop values.
Some common f stop numbers and their aperture openings.

I find a simple way to remember what f stops do, is this:

  • Small number = small amount of things in focus
  • Large number = large amount of things in focus

You then have to remember that a large opening (small number), will let more light in and a small opening (large number), will logically let less light in.

It’s important to keep in mind that a really wide-open aperture will make your photos soft or less-sharp. The same applies to the smallest aperture of your lens, so I suggest that you rarely shoot at the highest f stop. The softness you get in a photo taken at a low f stop number is the effect that you want, so it’s not such a problem.

How Aperture Affects the Depth Of Field or DOF

Earlier in this post I mentioned something called Depth of Field or DOF. This is a term for how much of your image is in sharp focus. Aperture has an huge affect on your depth of field.

Using a small f stop such as f1.8 will give you what is called a shallow depth of field. This means that the part of the photo that is in crisp focus will be very small.

In contrast, using a large f stop such as f22 will result in a large depth of field, meaning that more of the image will be in crisp focus.

See the images below for a comparison of the different DOFs you will get as a result of changing your aperture.

Still Need More Information About Aperture in a Camera?

For an in-depth look into what Aperture is, take a look at my “What Is Aperture – Aperture and How To Use It” YouTube video.

To learn about Aperture in relation to the exposure of your image, read my How To Use A DSLR Camera – The Basics Of Exposure blog post.

Thank you for taking the time to read this post today. Please come back for more blog posts, I post one on Tuesday and Thursday each week. Please share this post using the social media sharing buttons below.

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