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Photography 101: Introduction to aperture

Camera Aperture

Photo Credits: Andy Kirby

In this article, I shall be covering one of the most powerful and important aspects of photography, the Aperture.


1. What is Aperture?

Aperture is quite simply a hole in the front of your lens. Light enters the camera through this hole. It is very similar to the iris of our eyes; It controls the amount of light that enters the camera. Larger the hole, the more light gets in and smaller the hole, lesser the light that gets in. As simple as that.

Kid playing piano


2.Why is it so important?

Aperture is used to control the amount of light entering into the camera. Also, aperture (along with shutter speed) is among the two most crucial controls by which the photographer can control and portray his creativity. More specifically, It is used to control depth of field/DOF (the amount of focus you can have in your photographs)

Boat photo taken with f5.6 aperture

Photo Credits: Lucas Gilman

3. How does one use it?

Every nascent photographer must have been perplexed with the use of Aperture at some point. It is often confusing at first. We’ll try to break it down for you.
The size of the aperture is measured in a fractional measurement called f-stops. So, each aperture opening is an f-stop. You must have seen f/5.6, f/4.0, etc.. on the digital displays of your camera. The denominator (5.6 or 4.0) is the f stop number. That number represents the size of the aperture. Here is the trick,

The larger that f-number -> Smaller the aperture -> Lesser light -> Larger DOF
The smaller that f-number -> Larger the aperture -> More light -> Smaller DOF

Okay. If that makes you a little curious, here is some technical information (You may leave this part if you want as it doesn’t help you much in getting a good exposure):- F-stop represents the diameter of the lens opening. F — Focal length of the lens, and the number represents the stops in use. For example, if you are using a 300mm focal length lens and a f-stop of 5.6, then the diameter of the lens opening will be 53.57mm. Now, choose another f-stop on the same lens, say f16, and the diameter of the lens opening will be 18.75mm. Notice the change in size of the lens opening from 53.57mm to 18.75mm when the f-number changed from f5.6 to f16. This explain why a large f-number (say, f16) allows less light into the camera and a small f-number (say, f5.6) allows more light into the camera.

The choice of f-number depends on how much area of focus you want in your photograph. For example, f/22 would be ideal for a landscape shot where you want extended depth of field. At the same time, f/4.0 or so would probably be the right choice for a portrait shot/macro if you want an out-of-focus background.

Landscape photograph

Photo Credits: Skydancer

4. What does a ‘stop’ mean?

Stop down, f-stops, 1 stop, 2 stops etc are photography jargon which refers to amount of light. If you increase the f-number/f-stop from f8 to f11, the amount of light entering the camera reduces in half and if you decrease the f-stop (or stop down the aperture), the amount of light entering the camera doubles. So 1 full stop refers to halving or doubling of light. However, you may notice other numbers in between two full stop f-numbers in some cameras. For example, f/5.6; f/6.3; f/7.1; f/8; f/9; f/10; f/11. The numbers in red color are the basic stops and the numbers in between two basic stops are 1/3rd stops.


Closeup photograph of golden eagle

Photo Credits: Alan Hinchliffe

5.How do I set the Aperture on my camera?

Well, the way to do it varies from camera to camera. But the general modus operandi is as follows. Set your camera to Aperture Priority (Av or A mode) OR Manual mode. Locate the wheel/dial/button in your camera which controls the aperture (In old cameras and in some lenses, there is an aperture lever which is used to set the desired aperture). Then rotate the wheel of the camera to change the f-number which changes the size of the aperture.

Do it by yourself

If you see to know how aperture controls the amount of light getting into the camera, switch to the ‘live view’ mode of your camera (turning on your LCD) and change the aperture to different f-numbers. You can see that light is cutting down when you choose a high f-number and more light getting in when you choose a small f-number.

I hope you have an idea about aperture in photography now. Feel free to drop your comments.

Read: How to use aperture priority mode in your digital camera

NOTE: All images displayed are protected by copyright. Their reproduction, even in part, is forbidden without the explicit approval of the rightful owners.


Rohit is an avid photographer and an author at Shutter You can contact him via the buttons below.

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  1. Chandra Prakash says:

    All the basic treasure about aperture at one site…helpful, Thank you

  2. […] not be able to select a higher shutterspeed. In that case, you can boost the ISO or decrease the f-number/ or both to select a higher shutterspeed. I took the two images, shown below, using a canon 1000D […]

  3. […] set the EV value to -1 or -2 stops depending upon the brightness of the moon (Click here to read more on ‘stops). If you are photographing the moon just after sunset/just before […]

  4. […] one of our previous posts, we had given an introduction to aperture in digital photography. In this article I shall explain what is shutter speed and its significance in digital […]

  5. […] aperture priority mode: Use the aperture priority mode in your camera to have proper control over depth of […]

  6. 13 tips to improve your photography - ShutterStoppers | Digital Photography Tips and Tutorials says:

    […] #2 Get your basics straight: Learn different technical aspects of photography — aperture, exposure, ISO, shutter speed etc. Learn composition (the placing of the subject within the frame), […]

  7. […] f2.8 or lower. They are so called because it allows you to use faster shutter speeds since wide apertures let more light in the camera. Kit lenses are opened upto 3.5 – 5.6 range. At 55mm, the widest […]

  8. […] dealing with ISO is something which can be handled. But focusing speed is more related to the aperture of the lens being used as you need a lot more light to enter the camera for faster focusing […]

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  10. […] If you don’t know about f numbers, read: Introduction to Aperture in digital Photography […]

  11. […] Introduction to aperture in digital photography […]

  12. a lesson in taking portraits » Rebecca Fay Photography says:

    […] simple 50mm 1.8 lens. Set the camera to AV mode and open the aperture to about 2.5. Here is a great tutorial about […]

  13. […] Read: Introduction to Aperture […]

  14. […] If you want to know what ‘stops’ mean, read: Introduction to Aperture  […]

  15. Villa Malang says:

    If you don’t know about f numbers, read: Introduction to Aperture in digital Photography

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