Focal length

Filmmaker's Dictionary Feb 9, 2021

What is focal length?

The focal length is the distance from the optical center, where the light rays converge to the image sensor. It doesn’t represent lens size at all. The focal length of a lens is determined when the lens is focused at infinity and is usually measured in millimeters.

Focal length tells us about the angle of view of a lens. This are inversely proportional. This means that the shorter the focal length, the more of the scene will be captured. A lens with a very long focal length will also magnify the image significantly.

Types of lenses by focal length

Lenses of different focal lengths are used for very different purposes and produce wildly different effects. It’s important for any photographer and cinematographer to understand how to choose the best lens. Most lenses display their focal length on their barrel.

Zoom lenses cover a range of focal lengths and are therefore hard to categorize by it.

Prime lenses can be sorted into different categories.

Extreme or ultra wide-angle lenses have a focal length smaller than 24 millimeters. They have incredibly broad views, that are often distorted. Interior photographers often reach for this lens.

Wide-angle lenses have a focal length of 24-35 mm, capture a wide view of a shot and make subjects appear further away than they actually are. They’re often used for landscape and architectural images.

Standard lenses provide an angle of view that’s very similar to how humans see the world. They have minimal distortion and a neutral, familiar feel. Ranging from 35-70 mm, they isolate the subject from the background better than wide-angles.

Telephoto lenses are 70-200mm, and they’re very popular for portraits and photographing wildlife. They make the subject appear close to the camera. They have shallow depths of field, so making sure the subject is in focus is an absolute necessity.

Super telephoto lenses have focal lengths above 200 mm. They often require a tripod to support them, as they are big, heavy, and somewhat difficult to handle. Bird photographers can achieve the best results with this lens.

Summary

Different types of lenses fulfill different purposes. Ensuring you choose the right lens that fits your style and occasion is crucial to take outstanding images.

To learn more, you can read these Masterclass tips on how to pick the best lens.

Try different lenses and explore your creative potential!

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