A very, very common myth you’ll read around forums especially when discussing lenses of different focal lengths are the statements “just zoom with your feet”, “just take a couple of steps forward/back”, the idea was, moving with your feet gives you a similar image - it doesn’t.
Perspective of a scene changes when the subjects or the camera position moves towards or away the subject in relation to the background. However, merely zooming in and out from the same camera position will not alter perspective.
Take a look at this series of photographs (they are lousy examples, but I want to get the article out before I lose my train of thought, I’ll change them as soon as I get the chance).
The subject’s (scooter) relative size to the frame are about the same in all four image because I moved the camera's position. As I moved from wide to tele, I progressively moved the camera backwards in a straight line. The same focus point in my camera was used (left center), focusing on the black rectangle on the vertical bar of the scooter.
Rest of the article here...