Gregory Fraser wrote: > > Pardon my interruption but I think what Dave is talking about is > compression as opposed to perspective. The vertical and horizontal > placement of objects does not change from one focal length to another > however the relative size of objects does change with focal length as > does the apparent depth of the image. Doesn't it to you? The relative sizes stay exactly the same. And a change in perspective is pretty much defined as a change in relative position or size of objects. If a object A looks twice as large as object B, then changing lenses will not alter that relationship. The only exception is where the physical size (or construction) of the lens is such that changing lenses produces a change in the position of nodes which is a significant fraction of the object distance. OK, there'a another factor. If you're using a fisheye lens, an object to one side will have its size (and shape) distorted in a way that cannot be reproduced by a (presumably longer) rectalinerar lens. But then it's not going to appear in the same field of view either. Steve
