What is focal length in photography?

When shopping for a new camera lens it’s important to consider focal length. 

Scroll down to learn all about focal length and what it means in photography, along with why you might want to carry a variety of lenses in your kit. 

What is focal length in photography? 

Focal length is a number used to differentiate between different camera lenses. Focal length affects both the angle of view and magnification of a lens and is usually expressed in millimetres.

Common lens focal lengths are 35mm, 50mm, 70mm and 200mm.

The focal length of a lens is determined by the distance between a camera’s sensor and the lens’s sharpest point of focus when focused to infinity. This is the point at which light converges on its way to the sensor. 

As mentioned, focal length directly corresponds to the angle of view seen through the lens, with smaller focal lengths benefiting from wider angles of view and larger ones capturing more narrow angles of view. 

Likewise, focal length affects how close your subject will appear to the camera. Larger focal lengths magnify your subject, while smaller ones make them appear further away. On this note, it’s important to note whether you’re pairing the lens with a crop sensor or a full frame one, as an APS-C or Micro Four Thirds camera will see even further magnification due to the size of the camera sensor.

Lenses with similar focal lengths can be arranged into categories based on their effect on the final image. 

Standard lenses have focal lengths comparable to the human eye, making them well-suited for portraits and still-life photography. Wide-angle lenses fit more of your subject into the frame, making them ideal for landscapes. Telephoto lenses are ideal for shooting subjects from afar, while macro lenses capture more detail up close. Then there are more creative options, such as fish-eye lenses, that offer a distorted view that can add interest to cityscapes. 

Lenses can also be sorted into categories based on whether or not they have a single focal length. Prime lenses are typically smaller and have fixed focal lengths, while zoom lenses can be larger but offer variable focal lenses for further versatility. 

Regardless of what scenes you typically shoot, owning a wide variety of lenses will make it easier to get creative and capture new and interesting results with your camera.