Telephoto Compression
Rick Howie
Not a bird to be seen in the photo I suspect. But I posted it to show the effects of telephoto compression. Mt Baker is about 150 km to the south of the location where I took this photo of Vancouver.
Rick Howie
Kamloops
Rick Howie
I recently sent a picture of Vancouver & Mt. Baker and used it as an example of telephoto compression and my ignorance as it turns out. I am very grateful for the correction supplied to me by Alistair Fraser. With his permission, I share it with all of you so that you become more knowledgeable.
Thanks again Alistair. Much appreciated.
There is no such thing as telephoto compression,
— ergo, you cannot show its effects.
(Granted, you do show compression, it just doesn’t result from your lens.)
Telephoto compression ranks up there with the greenhouse effect as having an incorrect explanation imbedded in a name.
The point here is that the compression seen is not a consequence of a telephoto lens (telescope, binoculars, whatever).
Rather, the compression is a consequence of distance: The proportional separation between objects decreases as the viewing distance to them increases.
It is as simple as that.
Example: say you are viewing two things, one a metre from your eye, the other two meters from your eye. The second is twice as far as the near one and so it occupies only half the size on your retina. Now move farther away so that they are now ten and eleven metres from your eye. The fractional difference in size on your retina is now only ten percent. When compared to the viewing distance, the fractional difference in their separation has decreased.
So, this separation compression is a result only of viewing distance: It appears identically whether recorded with a wide-angle, normal, or telephoto lens — or for that matter with your unaided eye.
Why, then, do we suggest that this compression of distance with increasing distance is a consequence of a telephoto lens? Possibly, it is merely because we are more aware of the compression when a portion of the scene has been magnified.
Yet, I suspect the blame placed on the telephoto lens is closely related to another canard about these lenses: They bring objects closer. What a long lens does is increase the apparent angular size of objects. Granted, an object closer to us has a larger angular size and this leads to the simplistic assessment that the lens brought things closer. But, it didn’t. The distance to the objects has remained, as has the fractional distance between objects.
If we didn’t pretend that a telephoto lens brought things closer, but left things at the same distance and merely increased the angular size, we wouldn’t also have to pretend that it compressed distance for the spacing would still correspond to the original distance — something independent of the lens or eye used in the viewing.
I once listened to a professional photographer explain that one should always use a normal lens because, unlike a wide-angle or telephoto lens it did not alter the reality of the scene. This man blamed his equipment for altering the reality of space. Sad. He had spent too much time looking through lenses and not enough time looking with his eyes. He just did not realize that those other lenses were not altering the scene but revealing the reality of it.
Rick Howie
Decompressing in Kamloops
