Originally posted by Eruditass "Perspective distortion" is not created by focal length, but by your feet, which you often use to create identical framing. Two images with radically different focal lengths taken from the same physical spot have the exact same perspective relationship between objects. Crop a wide angle and compare it to a telephoto. There is a luminous landscape article on it.
Perspective distortion is created by altering the angle of view, which is directly influenced by focal length as well as by cropping the photo, but not at all by distance (Changing distance alters the perspective, but not the distortion).
The author of the Luminous Landscape article (if that is the article I'm thinking of) is hung up on fact number one (Changing focal length does not change the relationship of the the sizes of objects in the photo compared to each other.) and fails to resolve it with fact number two (Changing focal lengths does change perspective distortion.) He mistakenly thinks that fact number one contradicts fact number two. He does not have a complete understanding of it.
The mistaken understanding goes like this:
1. First, people discover fact number two, that changing their focal length changes perspective distortion. This is perfectly true.
2. Then people (mistakenly) reason out that if changing focal lengths changes perspective distortion, then it must change the relationship of the sizes of objects compared to each other in the photo. This is completely false.
3. People then learn that (2) is completely false, and using the same mistaken reasoning that made them come up with (2) in the first place, but in reverse, decide that (1) must also be false.
4. Using the same false premise that perspective distortion is caused by changing the relationship of the sizes of objects in the photo (which is what causes normal perspective changes), they conclude that perspective distortion is caused by changing distances to objects.
A big problem with this reasoning is that if perspective
distortion were caused by the same changes that normal perspective changes are caused by, then it would not
be distortion, but would be normal. Perspective distortion is caused by apparently altering one aspect of perspective, the viewpoint, without making the other corresponding changes in perspective, thereby causing it to become distorted, or give a false perspective. It is akin to an optical illusion.