What is F-Stop and How Should I Use It?

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Written By Nate Torres

You’ve probably heard the term “f-stop” mentioned when talking about photography, but do you know what it means?

F-stop is a crucial aspect of photography that affects everything from exposure to depth of field.

In this article, we’ll dive into what f-stop is, how it works, and why it’s important for photographers to understand.

F-stops can be a bit tricky to understand in the beginning, but it’s easy to understand once you know how it plays its part with aperture and the rest of the exposure triangle.

With that being said, let’s dive in!

In a hurry? Here are the key points:

  • An F-stop is a number based on your aperture. The numbers are fractions, making f/1.4 larger than f/22.
  • “F” stands for focal length, which means the diameter of the camera’s aperture blades.
  • Aperture helps you control the brightness/exposure and control the depth of field of your photos.
  • F-stop and aperture are essentially the same but different in the little details.
  • Choose your f-stop depending on the conditions, concept, and subject.
  • Although photographers commonly use higher/larger f-stops, the better option is using the medium f-stop. 
  • The best way to find the right settings is by taking some test shots at different f-stops. 
  • Change your f-stop whenever your subject moves front/backward or when an unwanted blur appears.

Read on for the full guide:

What is F-Stop in Photography?

The f-stop or f-number is the ratio between the lens focal length and the entrance pupil diameter. F-stop is the number shown in your camera that indicates the changes in the lens aperture size. It’s written as the f/2.8, f/4, etc., on the screen/viewfinder

Although some cameras may not display the “/” symbol or use a capital “F” instead, it still means the same thing.

Some cameras will also provide smaller f-stop numbers such as f/1.4 or f/22. 
When we say “larger f-stop,” what we mean is f/1.4, f/2, and f/2.8. But when mentioning “larger f-number,” it refers to f/11, f/16, and f/22.

Check out this chart for a visual guide:

aperture photography chart
aperture f-stop chart

So, how do you “count” the f-stop? And what’s the meaning of “larger” and “smaller” f-stops/f-number?

Smaller and Larger F-Stop

We have all been confused with the smaller and larger aperture concept. Yet, the hint has been in front of us the whole time.

The F in F-Stop is like a fraction.

To put it in practice, the f-stop of f/22 is equivalent to 1/22, and F/1.4 is the same as 1/1.4. Think of it as pizza slices. When you cut the pizza into a half (½), you will have a larger portion than cutting it into one-eighth (⅛), right? 
This metaphor perfectly explains why the smaller f-stop numbers (1, 2, 3, and 4) translate into a larger aperture and vice versa. 

The next time your mentor asks you to use a larger aperture, you should set your f-stop to f/1.4 to f/2.8. In contrast, when he/she recommends a smaller aperture, use the f/8, f/16, and so on. 
But… What does the “F” even mean?

What Does the F Stand For in F-Stop?

The answer is it stands for focal length.

If you have a Canon EF 70-200mm f/4 lens fully zoomed in, the aperture blades’ diameter will be 200mm. Then divide 200 by 4 (4 because it’s the max aperture), and you’ll get 50 as a result.

f stop aperture light
f-stop is the ratio between the focal length and the aperture blade diameter

It means that the diameter of your aperture blades in the lens will be precisely 50mm.
Using that example, we instantly know that the aperture blades will appear larger at f/1.4 and become ridiculously small at f/22. 
Is it necessary to always count the diameter of the aperture blades in the lens?

No, but this extended information about the camera mechanism will come in handy when you take on a professional project with rigid requirements. 

Why Aperture is Important?

Aperture will determine the focus and exposure of your image.

Smaller apertures will give a photo with throughout focus from foreground to background. On the other hand, larger apertures will only focus on the foreground while blurring everything behind it.

We have a full guide on aperture if you want to check that out later.

Your choices of apertures should be suitable for your photography vision. Does your concept need a specific focus? Do you want to focus on the foreground only or the whole scene?

If your concept requires a shallow focus on your subject, choose a larger aperture (f/1.4 to f/4). For landscape photography, it will be better to use smaller apertures ranging from f/8 to f/16.

Reference this chart again:

aperture photography chart
aperture f-stop chart

A larger aperture will allow more light to enter the lens and provide greater exposure. In contrast, smaller apertures will only let in half the amount of light as the larger aperture.

For example, an f/2.0 f-stop will allow 800 lumens into the sensor, while the f/2.8 only lets half of the original amount (400 lumens) touch the sensor.

But what is the best setting for macro photography when you want a vivid background? In this situation, your saving grace is bracketing and stacking.

By now you may wonder, are the f-stop and aperture the same thing?

Are Aperture and F-Stop the Same Thing?

Well, if you break down what f-stop is, it’s essentially the same. Most people use the terms f-stop and aperture interchangeably.

But if we want to be very accurate and precise, the difference is in the definitions.

Firstly, the f-stop meaning is the ratio between the focal length and the aperture blade diameter (f-stop = focal length/diameter as mentioned earlier). Meanwhile, the aperture is defined as the lens entrance pupil diameter.

Secondly, the aperture along with shutter speed will limit how much total light can reach the sensor. The combination of total light and sensor efficiency will determine the noise in your image.

That being said, the f-stop determines the intensity/density of light that will hit the sensor which is commonly known as exposure.

The density of light can be affected by lens length and the diameter of its opening.

The f-stop takes this into account, resulting in a relative aperture.

The f-stop can allow the same amount of light that other lenses can (limited by the maximum aperture).

How do I Choose an F-Stop?

Well, like I’ve said before, choosing your f-stop will be highly situational. 

Larger f-stop

A larger f-stop allows the image to focus on your subject/foreground while blurring the background.

Smaller f-stop

Meanwhile, the small f-stop will put both foreground and background into focus, but sacrifice the amount of exposure. 

Now let’s get a bit technical to make it clear.

  • When the lens is in focus, the image/video’s sharpness won’t be affected if you move the camera to the left or right. But, if you move it forwards or backward, the image/video will be blurry. 
  • ISO helps neutralize the exposure when you use the smaller f-stop. Set the camera to manual mode when you have a firm understanding of how both these settings and shutter speed work together.
  • The sharpness of the image will also depend on the picture’s dimension and megapixel size. A landscape picture may look fine in a 4 x 6. But when you blow it to 10×20, you’ll see some parts are out of focus. 
  • In theory, everything between the minimal and hyper-focus should appear sharp. In reality, if you try to get focus on your subject manually, you will get a better and more precise result. 
  • The depth of field calculator has interesting information that might help you during the photo session. But from my experience, it’s better not to use it.
  • The sweet spot for most f-stops would be the medium numbers which are f/2.8, f/4, and f/5.6. Try to do some experiments around these numbers to see which one suits your vision the best. 
  • Chromatic aberration will appear when you shoot a scene with high contrast. To avoid this, use a smaller f-stop or fix it in post-production using Adobe Lightroom or Photoshop editing software. 

In summary, the easiest way to decide the f-stop number is by taking some test shots. Take test shots starting from the largest to the smallest f-stop until your subjects are in focus. 

Don’t sweat about chromatic aberrations and vignettes because we can easily fix them in post-production. Prioritize to get the right sharpness and exposure.

Is the Higher F-Stop Better?

If what you mean by “higher” is a larger f-stop (f/1.4 and f/2), I must disagree.

Because having a higher f-stop does help you get as much light into the sensor as possible, but it will (again) completely blur the background.

bokeh in photography
higher f-stop creates that bokeh look

The smaller (below f/8) f-stop will also lead you to a problem because it decreases exposure.

The better option is to hover around the middle f-stop such as f/2.8, f/4, and f/5.6.

It will provide enough sharpness for both your subject and its background. Exposure levels will also be just right since it doesn’t allow too much or too little light.

Even so, the final decision is coming back to you. There are many genres/niches in photography, and all of them require different f-stops settings.

For example, macro photography needs large apertures to capture the small subjects with the highest sharpness. Landscape photographers tend to choose smaller f-stops to get a precise sharpness in the view.

When Should You Change Your F-Stop?

Changing f-stops should be done if your subject is out of focus.

Remember the focal length earlier? It guides us to change our focus and f-stop whenever the subject moves forwards or backward.

It would help if you also changed your f-stop whenever your photo is under-exposed or overexposed.

When vignette (edges in photo getting disproportionally darker), diffraction (basically images becoming less sharp the smaller your f-stop is), and chromatic aberration trouble you, it means that your f-stop is too small.

Hence indicating it’s time to change the f-stop.

Final Remarks

At this point, you should have already learned a lot about f-stops. This very flexible and functional feature can be tailored for every need.

Oh, and don’t forget to keep practicing to get a better experience of the f-stop mechanism. Good luck!

Frequently Asked Questions

What does a higher f-stop mean?

A higher f-stop, such as f/16 or f/22, means a smaller aperture opening, which allows less light to enter the camera and produces a larger depth of field. This is useful for capturing landscapes or group photos where you want everything in the frame to be in focus.

Is higher or lower f stop better?

The answer depends on the photographer’s intended outcome. A lower f-stop (e.g. f/1.8) is better for a shallow depth of field and blurred background, while a higher f-stop (e.g. f/16) is better for a deep depth of field and sharp background.

What effect does a low f-stop have?

A low f-stop (such as f/1.8 or f/2.8) creates a shallow depth of field, which means that only a small portion of the image is in sharp focus while the rest is blurred. This effect can be used to isolate a subject from the background or to create a sense of depth and dimension in a photo.