What is Aperture?
Aperture basically involves opening the lens and is measured in ‘f-stops’. Once you press the shutter release button on your camera a hole will open and allow light to hit the image sensor. The size of the hole depends on what you set as your f-stops value. A value of f/6 would allow less light through than a value of f/2, as the larger the number the smaller the hole. See the image below for a visual representation of this.
When you move to the next f-stops you will either half or double the opening of your lens along with the amount of light you allow through. A note to keep in mind is that if you move your shutter speed up or down one stop you also either double or half the amount of light, so for example if you increase the shutter by one stop and decrease the f-stops value by one stop, you will end up setting the same amount of light pass through.
Depth of Field
Aperture can affect your photos in a number of ways, but the depth of field is where you will see the most noticeable effect. Depth of Field or DOF for short describes how much of your photo will be in focus. A large depth of field will result in most of the image being in focus, where as a small, or shallow, depth of field will result in only part of the photo being in focus and the rest blurry.
The two images above show how the aperture can affect your images. The photo on the left shows a small, or shallow, depth of field as only part of the scene is in focus leaving the rest blurry, this was taken using a value of f/4.5. The image on the right shows a large depth of field as most of the scene is in focus, this was taken using a value of f/29.
Try it yourself
The best way to learn is to try it out and experiment for yourself, go and find a place that has items close to you as well as items further away. Once you have found a good spot start taking some photos using different aperture settings. Remember that a small f-stops number means a larger opening in your lens and a large f-stops number gives a smaller opening allowing less light to pass through to the image sensor.