If you photograph a subject with a tele lens and want it to have the same size on the sensor when photographing it with a wide angle lens, you would have to move closer to the subject. Because this would cause the perspective to change, lenses with different focal lengths are said to have a different perspective. Note however that changing the focal length without changing the subject distance will not change perspective, as shown in the next example.

A. Taken with a 24mm wide angle.

B. Cropped area from image A

C. Taken with 70mm tele, with the camera in the same position as in image A. Note that the perspective is the same as in image B.

D. Scene taken with a 24mm wide angle after coming closer to the subjects. The perspective is clearly different and the distance between the subjects appears larger than in image C.

Perspective distortion

Images B and C show that changing the focal length while keeping the subject distance constant has—just like cropping—no effect on perspective.

Image D shows that changing the subject distance while holding the focal length constant will change perspective.

Images C and D show that a tele compresses perspective (makes subjects look closer to one another), while a wide angle exaggerates perspective (makes subjects look more separated) compared to the normal way we see things with the naked eye. This is called perspective distortion. As mentioned earlier, this change in perspective is a direct consequence of the change in subject distance and thus only an indirect consequence of the change in focal length. Indeed, a wide angle lens allows you to capture subjects from nearby, while a tele lens allows you to capture distant subjects.