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10-28-2008, 06:23 PM   #16
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QuoteOriginally posted by audiobomber Quote
If I corrected the garage door, wouldn't I be correcting the perspective distortion also?
No. I think you're misunderstanding just what perspective distortion actually is.

In your garage picture, perspective is why the gray plastic storage tub on the floor along the left wall toward the *front* of the garage appears much larger than the (presumably) matching tub on the floor along the left wall toward the *back* of the garage. The one in the front looks bigger in this picture because it is so close compared to at the back. That is because we are using a wide angle lens that requires us to stand close to the garage in order to fill the frame.

Zoom to 250mm, and you'll have to stand *much* further away from the garage in order get the whole garage in the frame. When you get to the right distance, you'll find you are so far away that the distance between the two gray tubs pales in comparison to your distance from either of them. So the same picture would show *much* less difference in apparent size.

It works similarly for other objects in the garage. When you are close to it, as you need to be at 18mm, objects at the fron of the garage appear much larger than obejcts at the back of garage. Step back and shoot from 250mm, and things even out more.

This phenomenon is basic Perspective 101 and has been known to artists for centuries - it has nothing to do with lens distortion. It pretty much *completely* explains what the portrait demonstration was showing. At the longer focal lengths, the photographer was far from the subject, so all facial features were approximately the same distance away. As the photographer switched to shorter focal length, he had to move in closer and closer, and as he did so, the difference between the *front* and *back* of the head got more and more significant, just as it did with your garage. So features on the front of the face appear *much* larger and *much* closer than features toward the back of the face. This leads us to perceive the face as very distorted, but it is not the lens that is doing this distorting - it is an inevitable fact of being so close to the face.

We don't notice this in person because our binocular vision helps us make sense of things in three dimensions, but the effect can be very disorienting when reduced to two dimensions, as in a photograph or painting. And this effect is especially disorienting when it happens to a face, because of the special way our brain processes faces.

So what I'm saying is, even in a lens with 0% distortion, those wide angle views would have looked pretyt much exactly as distorted as they do here, because that's what perspective does to faces when you get that close.

10-29-2008, 09:39 AM   #17
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cool topic !
10-29-2008, 11:31 AM   #18
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QuoteOriginally posted by Marc Sabatella Quote
No. I think you're misunderstanding just what perspective distortion actually is.
You're right, I was confused by the term. Good explanation, thank you.

But I still think that lens distortion can be a significant factor in close-ups of faces. It causes a fisheye effect, far less obvious, but still there and quite noticeable and unflattering.
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