Zooming changes the shape: how to choose the right focal length

David Lee

27.5.2019

Translation: Patrik Stainbrook

Pictures: Thomas Kunz, David Lee

Whether you choose to shoot with a telephoto lens from a distance or with a wide-angle lens from close up, the subject will be just as big. And yet, it doesn’t quite look the same. It’s time to clear up this issue once and for all.

The longer the focal length, the smaller the field of view. In other words, by lengthening the focal length, you’re actually zooming in.

So far, so good. But zooming in isn’t the same as reducing the field of view. When you pick up a subject by zooming in, it looks different to when you’re close up to it. Even though it looks as big on the picture.

Side note: the size of the field of view depends on the focal length as well as the size of the camera sensor. All of the data in this article is based on a full-format sensor size (36 × 24 mm).

Here’s a simple example to show you how geometry changes according to the focal length. Strictly speaking, it’s not actually the focal length but the distance that causes the change.

The first picture was taken with 28 mm focal length, while the other was shot with 105 mm. They were both taken on a full-format camera. As you can see, the 105 mm image seems more natural and less distorted. Meanwhile, the distortion in the 28 mm image makes the bottle seem huge.

Even the layout of the room seems different depending on the focal length. In the photos below you’ll see four glasses from above (this time without alcohol!) When you photograph these glasses from the side, they look completely different in terms of focal length.

But it wasn’t just the distortion of the glasses that stood out:

Firstly, there’s the fact the red glasses look like they’ve been moved. They’re actually placed one behind the other but from a wide-angle they appear displaced. That’s because the camera is so far forward that it sees both glasses from a different angle.

Secondly, the distances appear much larger in wide-angle. That also has to do with the fact the camera is closer to the objects. The distance between the glasses is much greater than with the telephoto lens when you compare it to the distance from the camera.

Special case: portraits

When it comes to photographing bottles and glasses, we’re happy to turn a blind eye if it doesn’t turn out perfect – but not when it comes to snapping shots of faces. We’re much more discerning when it comes to these kinds of photos.

Smartphones usually have an awkward wide-angle, which can make faces distorted. You can limit the damage with selfies by choosing a more flattering angle.

But in fact, the best thing is not to photograph faces that close up.

The following portrait series demonstrates how the head and face shape change with increasing focal length. From 50 mm, it starts to look OK, but it’s better from 85 mm and beyond. Also notice how the background changes.

That’s not to say you can’t take shots of people with a wide-angle. It just means it’s best to take them from a certain distance so that you’re not just photographing the face.

David Lee

Senior Editor

David.Lee@digitecgalaxus.ch

My interest in IT and writing landed me in tech journalism early on (2000). I want to know how we can use technology without being used. Outside of the office, I’m a keen musician who makes up for lacking talent with excessive enthusiasm.

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