Photography Basics: Understanding Aperture

What Happens When You Click

To better understand what aperture is, we must first know how a camera works. Your camera is essentially a light-capturing device; light gets bounced off an object and is reflected into the camera. Light-sensitive materials in the camera then picks it up and saves it either as a digital image (JPEG, RAW), or onto traditional film. It works the same way as our eye does!

Size of the Hole

As you can see, the aperture of a camera works just like the iris of your eye. It controls the amount of light entering your camera, the bigger the hole, the greater amount of light, and the smaller it gets, less light comes through.

To change the size of the aperture, switch your camera to the aperture priority mode. This is indicated by either Av (for Canon cameras), or simply A (for Nikon and Sony users). When you switch into this mode, it just means that your camera goes into semi-automatic. You select the size you want, your clever camera does the rest.

Depending on your camera, as you turn the dial or push the left-right buttons, notice that the f-number changes as well. This f-number indicates the size of the aperture you'll be using. The bigger the f-number (eg. f16), the smaller the hole, the smaller the number is (eg. f3.5), the bigger the hole.

Note: The smallest and largest f-number can vary depending on the lens you have on your camera. It can go from f1 all the way to f22.

Take a bit of time to let this sink in as it works inversely on how we think about numbers and size, but with practise it will be second nature to you.

So what does this change of size do?

As it turns out, the size of this hole--aperture, also affects the amount of focus you can have with your pictures.

This amount of focus is called depth of field. When you have just the subject in focus and the background blurred out, we have a shallow depth of field. When both the subject and the background is in focus, it's called a deep depth of field.

Exercise: Controlling Depth of Field

The best way to learn a new concept is by trying it out first-hand. So grab your camera and put into practise what we have learned so far.

Tools needed:
A camera, peferably a dSlrYour subject, eg. Pencils you have lying aroundOptional: A tripod, or mini-tripod that comes free with most purchases

Setup

By default your camera will look at the scene and try to determine where to focus using its "clever brain." As we want control over where to focus on, we need to change some settings. We want to tell the camera where to focus, rather then let it choose for us.

Go to your camera settings, and change the AF point to the one in the centre.

Set your camera to aperture priority mode, and dial to the smallest number you can get (eg. f3.5)Focus on the pencil nearest to you by half-pressing the shutter button. Once it's in focused, press down fully to take the pictureNext, without shifting your camera around much--this is where the mini-tripod comes in handy if you have one, increase the f-number to f8. Focus on the same pencil and take the picture.Lastly, dial to f16 and take your picture.Save all your 3 images onto your computer

Notice how on the first image, the pencil you've focused on is sharp, but the pencils behind it is blurred out. Look at the second and third image. Notice how the pencils behind it starts to become sharper as we increase the f-number (f3.5 > f8 > f16).

If you've followed our exercise, congratulations! You've just moved out of the automatic mode and start to gain more control on your photographs.

Summary

Aperture controls the amount of light coming into your cameraThe smaller the f-number, the bigger the "hole," the bigger the f-number, the smaller it getsVarying the size also controls the depth of field, the amount of focus we can have on our pictures

Taking better images starts from taking control over your camera. Learning what aperture is and how it can improve your photography is a good start. But nothing beats taking what you've learned and applying it.

Take a look at some examples over at Singapore Photography.

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