F-stop and Aperture Explained

There are tons of videos, writeups, explanations, and what have you when it comes to your camera settings. You could probably spend 1 month, 24 hours a day, each day and only get through 1% of the material out there. There is information you want to know, there is information you have to know and there is information you really don’t need to know.

I decided to do Blogs on the 3 camera settings with the information you want to know and need to know and filter out the information that doesn’t really matter – like the mathematical calculation to determine why your f-stop is the number that it is – you don’t really need to know why your f-stop is 4.0 you just need to know what that means for your pictures.

So lets get started with the first Camera Setting: F-Stop and Aperture

First lets define a few words:

F-Stop or F-Number: This stands for 'Focal Length' Stop or number

Aperture: Simply means “opening" (Commonly used to describe the setting and basically interchangeable at this point)

Parts of a Lens:

A lot of people think the Fstop is a setting that is changed inside the camera body. While this is partially true, it is not the determining factor of your f-stop. The F-stop setting is actually determined by the lens you are using. It is a setting in the lens. Yes, you adjust it in the camera body, but its actually a lens setting.

You might have seen 2 lenses that look almost the same:

  • 24-70 f/4
  • 24-70 f/2.8  

The f/4 is $700 and the f/2.8 is around $2000. This is because the f/2.8 lens has a lower f-stop thus more expensive (more on this later). 

Why is Aperture important:

As I mentioned, the Aperture is the opening in the lens that allows light in through a mechanical device called “Aperture Blades”, also known as the Diaphragm in optics.

If you look inside your lens you will see a similar scene to the below. Shine a light at specific angles to see it better (minus the colorful lights you see in this photo haha).

These blades create a small opening (the aperture) and open and close to adjust the size of the opening and the amount of light let in. 

Here is where it gets a little interesting and took me a little time to wrap my head around it. When you adjust your F-stop, this adjusts the aperture (opening in the lens).

When you have a small fstop (1.8, 2.8, 3.2, etc.) your aperture is larger.

When you have a high fstop (10, 16, 22, etc.) your aperture is smaller. I will explain this a little later in a later section (Fstop).

                                 F1.4                                                      F16


You might have heard photographers say a “wide open aperture”, “stop down”, “open up” etc. These are referring to this setting.

What does this have to do with photos you might be thinking. The Aperture size effects certain qualities of an image. They primarily effect your Depth of Field and light allowed in.

What is Depth of Field? This is the distance between the first point of TRUE focus and the last point of TRUE focus. If you take a picture of a model, her face is in focus and everything behind her is out of focus, or blurry. The depth of field would be the points of focus. The blur, or Bokeh would be outside of the depth of field – this can be foreground and background.


What is Bokeh: This is the blurry, out of focus parts of an image. Used to create extremely aesthetic portraits and draw attention to the subject. You might have heard the term “Bokeh balls”. This is the effect created when lights are in the blurred part of the photo. 


Your Fstop can be adjusted in the following modes: Manual and Aperture Priority – On most cameras, the dial says “M” for manual. On Canon Cameras, Aperture Priority mode is “Av” – it stands for: Aperture Value. Other cameras are simply “A”

What is your F/Stop:

Let's get an understanding of F/Stop. This is also sometimes referred to as F-Number. In complex terms, it is a number that represents a ratio of the len's focal length divided by the diameter of the aperture.

That is the part you don’t really need to know. Lol. All you need to understand is the F-stop is a number that represents a fraction of the aperture. It is written as a fraction. Consider f/4 as 1/4 (one quarter) and f/16 as 1/16 (one sixteenth) and so on. The larger the number, the smaller the opening.  

If you’re not completely lost by now, you’re doing better than most! The important thing to take away from this is:

Small F-stop = More light allowed in = larger aperture opening

High F-stop = less light allowed in = smaller aperture opening

Quick test! Which will allow more light in? f/4 or f/8




You got it: F/4! That’s because the smaller the number the more light allowed in!  

Photo Attributes:

We discussed this a little earlier, but I wanted to go a little more in depth. Different F-stops effect the image in different ways. A wide-open aperture (low fstop) will allow a lot of light in, it’ll create a tight depth of field and is great for portraits, night photography or when you need a ton of light.

What about a large fstop (small aperture). This creates a much larger depth of field (DOF). It is great for landscapes or other images when you want everything in focus. However, the higher your fstop the less light will be allowed in. This you will need to compensate for by adjusting the other settings or adding more light.

Starburst are created when you are shooting into the sun at a high fstop (small aperture). The quality of the lens does come into play here and fun fact, so does the amount of aperture blades. If your camera has 4 blades you’ll get 4 sun rays. 8 blades, 8 rays. However, if you have an odd number of blades you will get DOUBLE, that’s right DOUBLE! The amount of light rays as you have blades. So, if you have 9 blades in your lens, you’ll get 18 sun rays.

The reason for this, is when you have even number of blades, the sunrays overlap. So in fact you have double sun rays, but because they’re in line, it looks like the same. However, in the ones that have odd numbers, they don’t overlap so you get double the amount of sun rays.

Some lenses are better than others. If you want to create images with this effect, look up lenses that create more defined and clearer sun burst.


Lenses and Max Aperture Sizes:

 As I mentioned earlier, you’ll notice lenses with different aperture sizes. Photographers will spend a lot of money for an extra stop. But why is that? Well, the difference between 2.8 and 4.0 is a full stop. An f/2.8 lets in twice as much light as an f/4.0. This can make a massive difference in a photo. It can sometimes even allow you to get a photo that you might not have been able to without that extra stop. 

Here is a scale that shows you the different stops:

                                              f/1.4                                               f/2.8

f/8                                              f/16



  •  Fstop is the number that represents a fractional size of your aperture
  • Since these are fractions, the smaller the fstop number, the larger the aperture opening and visa versa.
  • Just like your eye – the larger the aperture the more the light, the smaller the aperture the less the light. In turn, the larger the aperture (smaller fstop) the tighter your depth of field. The smaller the aperture (larger fstop) the more the whole image will be in focus.
  • Each lens has a max and minimum fstop. Most lenses will note their minimum fstop in the name. I.E. Canon EF 24-70 f2.8
  • The important thing now that you understand the theory of Fstop and Aperture is to go practice. Reading and understanding is one thing, but practicing will benefit you way more in the long run.
No one can tell you what experience will give you. Practice, Practice Practice!

So, get out there and Master that Photo!

Additional Resources
My Youtube Channel: Learn: Fstop and Aperture

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