Focal Length

Focal Length is the distance between the centre of the lens and the camera’s sensor. It measures this distance in millimetres. This is determined with the camera focused to infinity. Camera lenses are named by their focal length, for example the lens below is a 50mm lens.

Focal Length tells us the angle of view of the lens. The larger the focal length, the larger the subject within the the image but a narrower angle of view. Whereas, a lens with a smaller focal length makes the subject smaller but has a larger angle of view.

Focal Points

Focus Points are the little squares you see when looking through the lens of a camera. They light up sometimes when you half press the shutter button, but only one or two. Why is this?

When focusing the lens on to an image, you may think that the camera focuses on the entire image before it, however this isn’t true. Even though modern cameras are very smart, they can not focus on every little aspect of an image, the focus points tell you this. They show you where the camera is focusing and what part of the image will come out sharp and clear. In the image below, the points show the background will be in focus, whereas the second image shows that the flower in the centre will be in focus.

The camera will automatically decide where to focus but each of the focus points are looking for something to focus on, so it is really a game of luck. However, you can manually select which focus points you want the camera to use. On most DSLR cameras, there should be a button that you can press to do this; or you can go to the camera settings and choose from there.