Telephoto Perspective Compression
Posted Sunday, June 13th, 2010
I doubt if there is really such a thing as telephoto perspective compression, also referred to by camera users and photography enthusiasts as perspective distortion or flattening, despite these terms being in common usage. What they are talking about is the way telephoto lenses or binoculars appear to foreshorten the view, making distant objects appear to bunch up against nearer ones. It's only an optical illusion.
As the author of this article rightly says, long lenses do not compress perspective nor do they magnify background objects relative to foreground objects. This can be proved by physics and algebra, but it can also be demonstrated very easily with a camera, as I recently did myself when out walking with an acquaintance whose view on the subject was at that time clearer than mine.
As well as magnifying the scene, the second photo appears to stack the cars closer together than in the first: the so-called foreshortening effect of using a telephoto lens. Or at least it would to many people. This can be shown to be an optical illusion simply by digitally zooming in on the wide angle photo or by cropping it to the match the view in the telephoto version.
Except for differences in depth of field, the cropped wide angle photo is virtually identical to the telephoto one. The size of the cars relative to each other is the same in both pictures, which clearly illustrates that a telephoto lens does not compress perspective or foreshorten the view or make distant objects appear to be closer to foreground objects, or result in any other way of expressing the same alleged phenomenon.
A wide angle lens may well distort perspective compared to what you see with the naked eye but that is a different subject. A telephoto lens will not, at least perceptibly. This doesn't mean they can't be used to create dramatic effects, as they often are, but it's worth knowing this is purely by magnifying a selected part of the view.