FOCAL LENGTH EXPLAINED

Mike Harris explains how focal length is calculated, and shows you how different focal lengths affect your photos

- Mike Harris

Focal length is something 30 you might be familiar with. but be honest: do you MINS actually know what it is and how it's measured? Focal length is used to determine a lens's angle of view, which is what you see when you look through your camera's viewfinder. It's measured from the point where rays of light converge within a lens (the point of convergence) to the camera's sensor (or film), and is calculated while the focus is set to infinity.

Lenses with fixed focal lengths are known as prime lenses, and lenses with variable focal lengths are zoom lenses. Understanding the angle of view is crucial when identifying which lens to use, and it's something that seasoned photographers do on instinct. The smaller the focal length, the wider the field of view and more 'wide-angle' the lens. The larger the focal length, the narrower the field of view and more 'telephoto' the lens.

Focal lengths are often split into six categories. On the next page you'll find a breakdown of each category, and the genres of photography they're often associated with. It's worth noting that these parameters can shift slightly, depending on where you look or who you ask - we'd suggest that you treat them as guidelines that will help you get used to choosing the right focal length for the job. Ultimately, the best focal length will always be the one that helps to convey your creative vision.