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This post was most recently updated on January 8th, 2023

What is an aperture? What is an F-stop? Are they the same thing? To become the best photographer you can be, you’ll need to know the ins and outs of photography terminology. 

Apertures and F-stops can be pretty confusing at first and they can be tricky for beginners to navigate. It can be overwhelming, and with so many different answers online, you find yourself unsure of where to turn or who to trust. 

Well, no more! Today we are here to help you get the answers that you need. Keep reading to find out if the aperture is the same as F-stop and everything else that you need to know about them today.  

Apertures And F-stops Explained

Before we get into the article, let’s first explore what aperture and F-stops are. Apertures are the size of the lens on a camera. F-stops are used to measure how much light enters the lens. 

When you want to take pictures of something up close, you open your camera’s lens wider. This lets more light into the lens, allowing the camera to capture more detail. 

But if you want to get a picture of something far away, you need to use a smaller aperture. So when you’re taking a photo of something far away you need to open your lens up a bit and make the aperture smaller.

Aperture size is measured in millimeters (mm). The larger the number, the bigger the hole. The smaller the number, the smaller the hole.

Each f means focal distance and the numerator is a quotient when the focal length is divided by the diameter of the pupil. Anatomy of an F stop or F-number. In the past, the lens diaphragm was adjusted by inserting plates into the lens.

The plates were referred to as stops because they prevented light from going into the lens by changing the opening. 

The stops were made to double or halve the light intensity entering into the lens based on if it was removed or added. Aperture settings were then named after these stops: Smallest; 1/4 (1/2); 3/8 (3/4); 5/9 6/10 (6/5); 7/11 (7/6); and 8/12 9/13 (8/7).

Why Are They Used?

In the early 1900s, the first standardized automatic means of controlling the amount of light entering the lens became available. It consisted of two elements that could move relative to each other to control the size of the aperture formed by them.

These adjustments could not be made directly by turning knobs, as had been done before, since they moved along tracks that would have become too dirty over time.

At that point, however, another change in development permitted direct manual adjustment of the stop by rotating the barrel containing the mechanism.

Today, the only way to adjust the stop is by rotating this lever (which adjusts the iris blades inside the lens), but the name often remains unchanged. However, the F-numbers are also used to compare lenses with different maximum aperture sizes. 

For example, a 50 mm lens will normally have a maximum aperture of about ƒ/1.0, while a 100 mm lens will generally allow ƒ/2.0. Another type of exposure control is electronic flash.

There are three types of electronic strobes: high speed, low speed, and studio strobes. Each has its advantages and disadvantages in terms of cost, power consumption, color rendition, and coverage. 

Electronic flashes produce approximately a fraction of the light output of a traditional “bulb” system (Speedlight), though most are more powerful than a typical “studio” setting (the equivalent of 1/64th to 1/128th of full power).

Why Are F-stops Presented This Way?

F-stops are numbered this way because they’re fractions. When the numerator (the part before the decimal) gets bigger, the denominator (the part after the decimal) gets smaller. 

So, if you have an f stop of 1/2, it means that half of the light coming into your camera lens is blocked out by the diaphragm. If you have an f stop with a 4 in it, it means that four times as much light comes into the camera lens.

Higher f stops mean less light comes in. F-stops are numbered in order of increasing size. Aperture stops are named after the lens’ focal length. 

The smaller an f-stop number, the larger the opening in the lens. When you increase the size of the opening, you get a faster shutter speed.

For example, if you double the size of the opening (i.e., reduce the f-stop), you’ll need half as much time to expose the image. F-stops are a numeric value used to describe a camera’s aperture size. 

This number represents the ratio of the size of the entrance pupil to the size of the image sensor. A smaller f-number produces a larger depth of field and vice versa.

Square roots are difficult for most people to understand. For those who do understand them, the square root of 2 (√2) is the factor needed to double or halve an area.

F-stops are easier to understand than square roots because each number represents the ratio of the focal length of the lens to the diameter of the image sensor.

How To Calculate F-stops

aperture dslr

The formula for shutter speed is t f·tS, where t shutter speed, S seconds, and f focal length.

You can use math to calculate f-numbers from certain other numbers. To determine what f-number a given lens has, divide the focal length of the end of the lens closest to the subject by the distance between the front element and the image plane (the back cover of the film holder when using 35mm film.) 

Then multiply the result by the focal length of the rear of the camera. For many cameras, these numbers can be found on the printed labels that stick to the body of the camera or lens.

If you want to change the f/ number of a lens, take note that it needs to be removed first, then changed.

Differences Between Cameras

However, there are limitations such as some lenses may not support changing the f-number, others that do so require special tools or knowledge. 

On top of that, the minimum supported f-number varies widely among manufacturers, even within their lines—for instance, Canon’s entry-level EF-S 18–55 mm f/3.5–5.6 IS STM kit zoom uses an equivalent range of 16–35 mm; on the other hand.

Panasonic’s entry-level Lumix G 12–32 mm f/2.8–4 ASPH ultra-wide-angle lens supports 17–50 mm. 

This difference of 15 mm equates to 3 EV of difference in the maximum aperture at the widest setting.

What’s more, since each lens was originally designed for one particular type of exposure—such as sports photography, landscape photography, or wedding photography—each manufacturer tends to optimize its lenses for specific applications. 

For instance, Nikon’s AF-S NIKKOR 10–24 mm f/3G ED, while capable of covering the full-frame, is specifically optimized for portraiture, as it provides a fast enough aperture to ensure decent quality when shooting portraits. 

In addition, due to advancements in technology, newer models of professional DSLRs offer “faster” autofocus systems, allowing photographers to shoot at higher fps (frames per second).

Factors That Affect Flash 

Many factors affect flash power output. These include the following: 

  • Reflector design (to provide light to the photosensor)
  • The amount of ambient light entering the camera
  • The ISO sensitivity setting
  • The ability of the camera to meter correctly
  • The metering system settings on your camera
  • The shutter speed, the focal length of the camera lens
  • The position of the flash relative to the subject, 
  • Whether Auto mode or Manual mode is selected.


Hopefully, you now have a sense of how f-stops work. An f-stop of 2 is twice as wide as an f-stop of 1. Aperture sizes are expressed as fractions, so if you’re using an f-stop of 2, it means the opening is twice as big as when you used an f-stop of one.

If it’s dark outside, you’ll want to open up the aperture, making it bigger, like f/1.4 or f/3.2.

Aperture refers to the size of the opening in your camera’s lens. Lenses come in different sizes, including wide-angle lenses (like the 50 mm), normal lenses (like the 24-105 mm), and zoom lenses (like the 18-200 mm). Each lens has a specific maximum and minimum aperture setting. 

You can change the aperture by turning the lens ring on your camera body. The larger the number, the wider the opening. When you use an aperture of f/2.0, half of the light that enters the lens goes straight through to the sensor.

This means that there is less light reaching the sensor, making the picture darker.

The lower the number, the more light gets into the lens, and therefore the brighter the picture. Most cameras let you choose from three different settings: wide open (f/1.4), medium (f/3.5), or narrow (f/6.3).

There are other effects of aperture besides exposing the right amount of light to your subject. 

Depth of field is also an effect of aperture. You should know about both of them. Large apertures provide a shallow depth of field. Aperture values of 2.8, 8, and 16 are common settings for landscape photography. Shallow depth of field is ideal when you want to emphasize the background.