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Photography 101: Shooting in Manual: Aperture

So, what is aperture? Aperture is a part of the exposure triangle that effects depth of field , or how much of the photo is in focus. Part 3 of our series on shooting in manual discusses what is aperture and how to use it.
What is aperture? aperture affects your depth of field

Taken with Canon 6D and Canon 35mm 2.0 lens

Settings: Aperture f/4 Shutter Speed 1/400 ISO 800


Aperture is the 3rd part of the exposure triangle that we are going to talk about.  But exactly what IS aperture? One of the things that gets people confused is that aperture is often described in different terms: aperture, f stop, and depth of field. The problem is that although they are all used interchangeably, they really all have a different meaning.


Your aperture controls how much light is able to enter your camera. Technically, an aperture is the opening inside of your lens that can open up wide or can close down very narrow.

What IS aperture? Aperture is one of the most important parts of the exposure triangle is aperture. Understanding it will help you shoot in manual.


f stop

An f-stop is written like an equation. The f-stop corresponds with how wide the aperture( the opening) inside your lens is. Traditionally, f-stop is written like f/4.0 but you will see it as f4.0 or even just 4. F-stop can range from f/1.4 to f/32 depending on the lens in the following increments: f/1.4 f/2 f/2.8 f/4 f/5.6 f/11 f/16 f/22 f/32.

Note, the f-stops I gave you are considered full f-stops.  If you see f-stops in any other increments, they are half,third or quarter f-stops.


The lower the f -stop number, the wider your aperture is opened. And the higher the f-stop number, the more narrowly the aperture is opened.

Reread that and look at the diagram above.

It’s important that you get this.

So, if looking at the diagram above, you can see that an f-stop of f/2.8 means that your aperture is WIDE OPEN while an aperture of f/16 means your aperture is closed down very small.


A LOW  f-stop number means you have a wide aperture which means you are allowing MORE light into your camera.

A HIGH f-stop number means that you have a narrow aperture which allows LESS light inside the camera.

A wide opening inside the lens (a small f-stop number, like f/1.4) is also considered:

  • having your lens ‘wide open’
  • a ‘wide aperture’
  • a ‘large aperture’
  • a ‘fast aperture’
  • a ‘maximum aperture’

And a small opening inside the lens (a large f-stop number, like f/22) is also considered:

  • having your lens ‘closed down’
  • a ‘narrow aperture’
  • a ‘small aperture’
  • a ‘slow aperture’
  • a ‘minimum aperture’

Unlike shutter speed and ISO settings, which are based on the capabilities of your camera, aperture settings are based on the capabilities of the lens you’re using. One of the single biggest factors in determining the quality (and the price) of a lens is how wide its aperture will open.

What is aperture and how do you find it on your lens?

If you want to know how wide the aperture on your lens will open, grab a lens and look. There are numbers either on the outside of the lens or inside the rim of the lens.  Look for a “1:” to tell you your maximum or widest aperture. On the lens above it says 1:2.8. that means your widest aperture is f/2.8.

Now if it says something like 1:3.5-5.6, then you have what they call a variable aperture lens. meaning your aperture will vary depending on how zoomed in or out you are. If you are zoomed out away from your subject, the widest that your aperture would be would be f3.5. When zoomed in, the widest your aperture would be would be 5.6. Each time you zoom, your aperture changes.

Depth of Field

What makes aperture such an important aspect of our photography, is the ability of aperture to affect our Depth of Field. Depth of field is the amount of your photo that is actually in focus. The smaller the f/stop, the smaller your depth of field. The larger the f-stop, the larger your depth of field.

A LARGE depth of field means that a large of amount of your photo will be in focus.  SO both the foreground and the background will be in focus.  You would get this with an aperture of  f/22 like the photo below.

Your aperture effects your depth of field.

Taken with Canon 6D and Canon 24-105 f/4 L lens

Settings: f/22 SS: 1/200 ISO 400


A SHALLOW depth of field means that only a small part of the photo will be in focus. And the rest will be blurry or have Bokeh. You might get this with a aperture of f/2.8.

aperture affects your depth of field.

Taken with Canon 6D and Canon 40mm f 2.8 Lens

Settings: f/2.8 SS 1/640 ISO 1600

So that is a brief description of what is aperture! And of COURSE! I have included this handy cheat sheet that you can download right here! Or, you can just click the photo below to download.

Aperture Cheat Sheet


Now, stay tuned tomorrow where we wrap this all up and get you shooting in manual! If you missed the first 4 posts in this series, just check out the posts below!

*this post contains affiliate links*

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Learning to shoot in manual shouldn't be hard! Today we are talking about mastering ISO and why high ISOs are not always a bad thing.
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