Perspective

Perspective is the relative change of size of subjects at different distances to the camera.

Perspective changes with the distance to the subject. Changing the focal length does not change the perspective. To change only the perspective you must change both the distance to the subject and the focal length so the subject is framed identically from a different distance.

The difference in apparent size of the two subjects will be come smaller as the camera moves further away.

At extremely long distances the perspective becomes completely flat and there is little or no difference of apparent size between the subjects.

Perspective vs focal length

These two pictures were taken with a 50 mm lens and a 10 mm lens with a 5x crop factor. The distance between the coins are the same as the distance between the tip of the nose and the earlobe. The relative size between one coin and the other and between the coins and the background is identical in both pictures so the perspective must by definition be identical in both pictures. This shows that the focal length of a lens does not affect perspective.