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I'm trying to get my head around perspective. If you look at the animation in Wikipedia :

enter image description here

You can see that the cube looks very distorted, then the edges go more parallel.

From my understanding, the distorted version is when the camera is very close to the cube, and the less distorted version is when the camera is further away.

But if the camera is further away, why does the cube not appear smaller?

Is this something to do with keeping the "field size" constant? Is the field size a flat area? Or part of the area of a sphere? It looks as though you can see more stuff in the background and foreground when you're zoomed out compared to zoomed in, so how can you know that you're keeping the "field size" constant?

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Migrate to photo.stackexchange.com ???? –  Mr.ØØ7 May 31 '13 at 12:46
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1 Answer

The animation does not represent what our eyes would see.

If you go far away from the cube you will see its faces more parallel, but the cube will be smaller, just as you explained. You can then use binoculars to make it bigger, and the faces will remain parallel.

The computed image scales the image up to make it appear bigger, just like what binoculars do.

In optics terms, the eye sees an object with a given magnification (ratio of sizes) and the computer adds an additional magnifying power (ratio of angles) such as the one provided by binoculars.

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