What does the f in f stop stand for?

What does the f in f stop stand for?

The f in f stop stands for the focal length of the lens. So when I say a lens has an f-stop of f/2.8, the ‘f’ refers to the focal length, and the 2.8 tells you the size of the aperture opening in the lens. The lower the f-stop number, the wider the aperture opening.

Why does aperture matter? Well, it controls how much light enters the camera and also affects something called depth of field. A wider aperture (lower f-stop) lets in more light and decreases depth of field – which means you get that nice blurry background effect. But a narrower aperture (higher f-stop) lets in less light and increases depth of field – so more of the image will be in focus.

It can get confusing, I know! I remember when I first started out, I would always mix up which way the f-stops went. Lower number, more light, blurrier background – that was my mantra! Eventually it became second nature.

The key is not to get overwhelmed. Just remember that the ‘f’ stands for focal length and the number tells you the aperture size. And don’t be afraid to experiment – creativity comes from learning how different settings affect your photos. The technical terms will start to make sense with practice. Until then, just keep shooting!

Understanding F-Stops: A Comprehensive Guide to Using F-Stops in Photography

The aperture is measured by the F number, also known as f-stops as we have explained before, which determines the size of your aperture; a larger aperture allows more light to enter like the pupil, while a smaller aperture becomes smaller letting less light to enter in the camera.

What Are F-Stops and Why Do They Matter?

F-stop stands for the focal length divided by the effective aperture diameter of a photographic lens. It is a quantitative measure that indicates the size of the lens aperture relative to the focal length. The f-stop is a calibrated measurement scale used to control the amount of light reaching the camera’s sensor by adjusting the size of the aperture opening in the lens.

Understanding how to use f-stops is crucial for photographers looking to exert precise control over exposure and depth of field in their images. The f-stop impacts the photograph in the following ways:

  • It controls the total amount of light entering the camera. A larger f-stop opening (lower f-number) allows more light in, while a smaller opening (higher f-number) allows less light in.
  • It determines the depth of field – the region in focus from front to back. A larger f-stop gives a greater depth of field, while a smaller f-stop gives a shallower depth of field.
  • It lets you achieve consistent exposure using different combinations of shutter speed and ISO at a fixed f-stop.

In essence, the f-stop provides a standard reference point for the photographer to calibrate the exposure based on the lighting conditions. Mastering the use of f-stops is a fundamental photography skill that gives you creative possibilities in image capture.

Where Does the Term “F-Stop” Come From?

The origins of the term f-stop can be traced back to the early 20th century. It comes from the use of the letter “f” to denote the focal length of a photographic lens. F stands for focal length, while stop denotes the aperture setting that controls the amount of light entering the camera.

The original meaning of stop comes from the aperture control dial present in early cameras. Photographers would literally “stop down” the lens to a smaller aperture opening to reduce the light coming in. This gave rise to the term stopping down the lens. Early lenses had aperture settings marked on the dial as Stop 1, Stop 2 etc. This eventually evolved into the f-stop scale in use today.

The f-stop combines the focal length of the lens with the relative aperture opening into one numeric value. For example, a 50mm lens set at f/2.8 tells you the focal length is 50mm and the aperture diameter is 50/2.8 = 17.9mm. The f-stop provides the photographer with the key information about aperture and focal length in one simple number.

The Relationship Between Aperture and F-Stops

The f-stop scale is directly related to the physical diameter of the aperture inside the lens. Adjusting the f-stop changes the size of the aperture and thereby controls the amount of light entering the camera.

A larger f-stop opening (lower f-number) corresponds to a wider aperture diameter, which allows more light to hit the camera sensor. For example, f/2 lets in twice as much light as f/2.8.

A smaller f-stop (higher f-number) means a narrower aperture, which gives less light to the camera sensor. For instance, f/8 admits half as much light as f/5.6.

Each f-stop either doubles or halves the amount of light from the previous stop. Lower numbered f-stops signify a larger aperture opening, while higher numbers mean a smaller aperture. Understanding this fundamental relationship between f-stop and aperture is key to mastering exposure.

Why Are F-Stops Numbered That Way?

The f-stop scale may seem counterintuitive at first because lower f-numbers actually indicate a wider aperture, while higher numbers mean a narrower aperture. This inverse numbering has its roots in the way f-stops are mathematically calculated.

The f-stop number represents the ratio between the focal length and aperture diameter of the lens. For example, a 50mm lens at f/2 has an aperture diameter of 50/2 = 25mm.

Since aperture diameter gets smaller as you stop down, the ratio gets larger. The higher f-number is proportional to a smaller aperture. This is why lower f-stop values mean a wider aperture.

Once you understand that the f-number is a ratio, it is easier to grasp why the sequence goes counterintuitively from a lower number (larger aperture) to a higher number (smaller aperture) as you stop down.

How Do F-Stops Affect Exposure?

The most direct impact of changing the f-stop is on the exposure. Wider aperture openings let in more light, while smaller openings reduce the amount of light hitting the camera sensor.

Each full stop increase or decrease of f-stop doubles or halves the amount of light entering the lens respectively. For example:

  • f/2 gives twice as much light as f/2.8
  • f/4 gives half as much light as f/2.8
  • f/5.6 gives half as much light as f/4

So f/2 will have 4 times more light than f/5.6 (2 stops difference). This allows you to increase or decrease exposure a desired amount simply by changing the f-stop.

You can use the f-stop in combination with shutter speed and ISO to obtain your required exposure. For a given ISO and f-stop, increasing shutter speed reduces light, while slowing shutter speed increases light. The flexibility of f-stops allows you to vary the shutter speed/aperture combination as needed to suit the shooting conditions.

How Do F-Stops Affect Depth of Field?

The f-stop also determines the depth of field in your images, which is the zone of acceptable sharpness extending in front of and behind the focused subject. Wider apertures (lower f-stops) give a shallow depth of field, while smaller apertures (higher f-stops) give a large depth of field.

This happens because wider apertures produce a narrower cone of sharp focus extending from the lens. The sharp region is confined only to the plane of focus. But with a smaller aperture, the cone of focus is much wider, bringing more foreground and background into focus.

So f/1.4 will give a soft, blurred background while f/16 will make the whole image evenly sharp from near to far. You can use f-stops creatively to control whether your background is soft or sharp.

What Are Some Common F-Stop Values?

While theoretically f-stops can range from f/0.5 to f/90 or more, lenses for 35mm cameras typically have apertures ranging from f/1.4 to f/22. Here are some of the full stop f-stop values you will encounter:

  • f/1.4 – Very wide aperture available in prime lenses and telephoto zooms. Gives shallow depth of field.
  • f/2 – Also a fast aperture used in many prime lenses. Gives soft background blur.
  • f/2.8 – Popular maximum aperture in zoom lenses. Gives good subject/background separation.
  • f/4 – Medium aperture, common in consumer zoom lenses. Good for many general shooting situations.
  • f/5.6 – Typical midpoint aperture in consumer zoom lenses. Starts giving decent depth of field.
  • f/8 – Smaller aperture useful in daylight. Provides good sharpness across the frame.
  • f/11 – Gives crisp sharpness from near to far. Used in landscape photography.
  • f/16 – Very small aperture. Used in very bright light or for long depth of field.
  • f/22 – Minimum aperture on most lenses. Gives maximum depth of field.

How Can You Control the F-Stop?

DSLR and mirrorless cameras provide multiple options to adjust the lens aperture through the f-stop settings:

  • Aperture Priority mode – You set the desired f-stop and the camera selects the appropriate shutter speed to match the exposure.
  • Manual Mode – Full manual control over both shutter speed and aperture. Lets you achieve the exact exposure you want.
  • Lens aperture ring – Higher end lenses have aperture control rings that let you directly adjust the f-stop. Useful in manual video work.
  • Camera aperture dial – Some mirrorless cameras have a dedicated dial to change the aperture value. Simplifies manual aperture control.
  • Through the menu – You can set the aperture via the camera menu if your lens does not have an aperture ring.

Start by learning to adjust the aperture in Aperture Priority mode. Once you have a grasp of its effect, use Manual mode for precision control over exposure along with aperture.

What does the f in f stop stand for?

How to Read Aperture Markings on a Lens

Lens aperture settings are marked in standard f-stop values like f/2.8, f/4, f/5.6 etc. Here are some ways aperture size can be denoted on lenses:

  • As the minimum value – e.g. f/3.5-5.6 means min aperture is f/3.5 and max is f/5.6
  • As a fixed value – e.g. f/2 means aperture is fixed at f/2
  • As a range – e.g. f/2-f/16 shows the aperture range
  • As 1/2 stops – 1/2 stop settings like f/5.6 and f/6.7 may be marked between full stops

When reading aperture values off a lens, note whether they represent a fixed aperture or a variable range. The minimum aperture is usually the fastest (lowest f-number) in a zoom lens. Check your lens markings to know the aperture range available.

The Difference Between F-Stop and T-Stop

In photography, the related concept of T-stop denotes the actual light transmission through a lens. While f-stop refers to the ratio of focal length to aperture diameter, t-stop indicates how much light is practically transmitted after accounting for lens coating, glass elements etc.

For example, an f/2.8 lens may have a t-stop of f/3.2. This means although its aperture ratio is f/2.8, the actual light passing through the lens is equivalent to f/3.2, a 1/3 stop difference.

T-stops are more important in film and video work where consistent exposure between lenses is required. In still photography, you can simply adjust exposure slightly to account for differences in lens transmission.

How to Use F-Stops Creatively

Here are some tips on how to take creative advantage of f-stops in your photography:

  • Use wide apertures (f/1.4 – f/2.8) to create soft, blurred backgrounds and make your subject pop. Great for portraits, food, macro and more.
  • Stop down to f/8 or higher for panoramic landscape shots to get everything sharp from near to infinity.
  • Try narrower f-stops like f/16 when using flash to balance ambient exposure with flash.
  • For long exposure waterfalls or misty scenes, use narrow apertures like f/22 for extra depth of field.
  • Get cool sunstars on specular highlights by stopping down to f/16 or f/22 when shooting into the sun.
  • Track action and wildlife with fast prime lenses wide open at f/2.8 for narrow depth of field and fast shutter speeds.

F-Stop Cheat Sheet

Use this handy f-stop cheat sheet to help memorize the f-stop scale and depth of field characteristics:

  • f/1.4 – Very shallow depth of field. Ideal for dramatic portraits with blown background.
  • f/2 – Shallow depth of field. Great for subject isolation with soft background.
  • f/2.8 – Moderately shallow depth of field. Popular maximum aperture in zoom lenses.
  • f/4 – Begin to see noticeable depth of field. Good walkaround aperture.
  • f/5.6 – Increased depth of field with adequate subject separation.
  • f/8 – Good sharpness throughout image. Common for landscape photography.
  • f/11 – Excellent sharpness from foreground to background. Also used for landscapes.
  • f/16 – Maximum depth of field available in most lenses. Useful in bright light.
  • f/22 – Extreme depth of field. Used in very bright conditions.


Learning about f-stops in depth equips you with invaluable skills in photography. The ability to vary aperture using f-stops gives you immense creative control over exposure and depth of field in your images. Master its use in different photographic situations to take your skills to the next level. Some key takeaways:

  • F-stop denotes the ratio between focal length and aperture diameter of a lens
  • Lower f-number means larger aperture, more light and shallow depth of field
  • Higher f-number means smaller aperture, less light and more depth of field
  • Each f-stop doubles or halves light from the previous stop
  • Use wide apertures for blur, narrow apertures for sharpness front to back
  • Adjust f-stop along with shutter speed and ISO to get desired exposure

When starting out in photography, the terminology like f-stops explained and aperture settings was really confusing as a new photographer. Trying to grasp concepts like field of view and depth of field with all the lens measurements like f-number and aperture size felt overwhelming at first. However, with practice using my camera’s aperture in different lighting and shooting one stop up or down, I began to understand how aperture allows more or less light entering.

Though photography requires continuous learning, getting comfortable with settings like variable aperture lens and small f-stop has given me more creative confidence. My advice to new photographers is be patient, experiment with size of your aperture through the aperture scale, and don’t let technical terms like known as f-stops intimidate you. With regular practice wide the aperture, the concepts like aperture to achieve your goals will make sense. Photography is always a learning process, but you have to start somewhere.

FAQ about F-Number

What does the f in f stop stand for?

The “f” in f stop stands for “f-number”.

Q: What is an f-stop?

A: An f-stop is a measurement of the aperture size on a camera lens, which controls the amount of light that enters the camera.

Q: How does the aperture size affect a photograph?

A: The aperture size affects the depth of field in a photograph. A larger aperture (smaller f-number) creates a shallower depth of field, while a smaller aperture (larger f-number) creates a deeper depth of field.

Q: Is f-stop the same as shutter speed?

A: No, f-stop and shutter speed are two different settings on a camera. While f-stop controls the aperture size, shutter speed controls the duration of time that the camera’s shutter is open.

Q: What is ISO?

A: ISO is a measure of a camera’s sensitivity to light. A higher ISO setting makes the camera more sensitive to light, allowing for better performance in low-light conditions, but it also introduces more digital noise in the image.

Q: How does the f-stop scale work?

A: The f-stop scale is a series of numbers that represent the different aperture sizes. Each full f-stop change either doubles or halves the amount of light that enters the camera.

Q: What is a digital camera?

A: A digital camera is a camera that captures and stores photographs in digital format, as opposed to traditional film photography.

Q: How does the aperture and f-stop relate to each other?

A: The aperture is the physical opening in the lens that controls the amount of light entering the camera. The f-stop is a measurement that indicates the size of the aperture.

Q: What is the widest aperture on a camera lens?

A: The widest aperture on a camera lens is typically represented by the lowest f-stop number.

Q: How is the aperture measured?

A: The aperture of a lens is measured by the diameter of the entrance pupil, which is the opening that allows light to pass through the lens.

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