 Photography is all about capturing light. A camera captures light that enters through the lens using a sensor to digitize the information and create a photograph. This video will look at one of the camera's key functions, aperture. The aperture is the hole at the front of the camera where the light enters. Digital SLR cameras have a whole range of features, lenses and accessories to change and optimize the light that goes into the camera. The vast array of dials and settings you get on a good camera can be quite daunting at first. In fact, most people start on the green square setting that gives almost full automatic function to the camera. However, to get the best out of a camera and be truly creative, it's best to take some time and understand how to use some of the manual functions. To make experimenting with aperture easier, aperture priority mode will give you the creative freedom with aperture whilst the camera helps you automatically with the other settings, such as shutter speed and ISO. Simply turn the dial to the AV. The size of the aperture can be changed in small increments, changing the amount of light that is captured by the camera. As you would expect, the bigger the aperture or camera hole, the more light the camera takes in. And conversely, the smaller the aperture, the less light it takes in. To select the aperture, press this button here. You can then adjust it using the dial while the button is held in. The size of the aperture opening is measured in f-stops. It may seem confusing at first, but remember that the smaller the number, the larger the aperture size. For example, f2.8 will allow more light into the camera than f16. So let's take a look at the aperture scale. In normal daylight, you will probably want to start with around f8. If the photo looks too dark, simply open the aperture up a bit, say f4, until you have the right balance. If it's too light, close the aperture slightly around f11. As all lighting conditions are different, it's best to play around and see what works for your location and subject. There is another really interesting effect of changing the aperture size. You can vary how blurred the background of your photo is. The wider the aperture, that's low f numbers, the more blurred the background will be. This means when you're photographing something, it'll give the image that extra punch as the background becomes less distracting. As with all good photos, take some time to think about what you want your photo to look like and adjust the camera settings accordingly. To switch your camera to manual mode, simply turn the dial to M. You'll also need to change your ISO to manual, as by default that's set to automatic. If you need help on this, check out our other video on ISO. In certain scenarios, you may want to capture an image with a wide aperture to ensure a blurred background when the lighting outside is bright, for example using f2.8. To compensate for more light being let into the camera, you will need to have a faster shutter speed. For example, on a very bright day, one one-thousandth of a second might be a good starting point. There are three fundamental factors that are important for every photographer to understand, all of which affect the amount of light that goes into the camera and how the camera performs. These are one, the aperture, two, the ISO number, and three, the shutter speed. They all work in tandem with each other and are therefore often referred to as the exposure triangle. You will find separate videos available for the ISO number and shutter speed in more detail and we recommend you take a look at these.