How Focal Length Affects the Background of a Photo

Photography Tips

The choice of lens for your camera can significantly affect two major aspects of your photos: the angle of view that you capture and the extent of background distortion. But hang on a second. Does changing the focal length only determine background compression? This eye-opening video proves otherwise:

Angle of View

Before we get into background compression and expansion, we need to understand angle of view. Angle of view determines how much of the scene you’re going to capture in your photos.

Angle of View with a Wide Angle Lens

With a wide angle focal length, such as the Canon 24-105mm L lens set to 24mm, you’re going to get a sweeping perspective of the scene in front of you. Your subject, whether it is a human being, an animal, or a house, is going to look small. With a telephoto lens such as a 70—200mm, the subject will appear much closer and fill the frame.

Background Compression & Expansion

Wide vs. Telephoto. Shot from the same distance, no difference in background distortion.

In reference to the image above, what is to be noted is that the distance between the photographer and the model did not change while swapping lenses.

According to popular belief, changing lenses should have rocked the background perspective. As the comparison above suggests, that’s not really the case. The image one on the left was taken with the wide angle lens and the one on the right with the telephoto lens.

There is a significant difference in depth of field, but that is beside the point. So, why do professional photographers claim that changing the focal length can result in background compression or expansion? Because with changing focal length, something else also needs to be changed.

Camera to Subject Distance

The reason you would want to change the subject to camera distance is to keep the same framing. With a wide angle lens you have to get close enough to your subject to be able to do that. With a telephoto lens, you will have to step back to keep the same framing, and therein lies the mumbo-jumbo.

When you step in with a wide angle lens the background is pushed back. When you step back with a telephoto lens the background is sucked in.

Here are a series of images taken at various focal lengths and varying camera to subject distances to prove the point: