Probably a really stupid question...

[Jonalee]

....but my brain hurts from trying to find the answer myself.

I remember coming across a site that showed a red water bottle in the foreground and a blue water bottle in the background. In the series of shots, the red water bottle stayed the same size, but it appeared as though the blue bottle was being brought closer and closer, until the final picture in which it was the same size as the red water bottle.

What in the world is this called? I would like to learn more about how it works, but I've been racking my brain trying to remember how I came across it, but I can't.

I know, I'm might as well have a neon 'noob' light flashing on my forehead right about now, but I'd appreciate any insight you can give me. It doesn't have to be the water bottle shot. Something similar would be just fine by me.

[OsmosisStudios]

I've never heard of such a thing. It could be focal length breathing.

[BryanC]

It sounds like the photography version of a cinematography technique known by different names such as Vertigo zoom, Hitchcock zoom, dolly zoom, smash zoom or reverse tracking. It changes the perspective between the foreground subject and background subject by either zooming in on the foreground subject as the camera moves further away at the same rate, keeping the subject the same size in the frame or, vice-versa...zooming out as the camera moves in closer. Either way, it keeps the foreground subject(s) the same size in the frame while the background appears to grow or shrink in size.

The names "Vertigo zoom" and "Hitchcock zoom" are often used for the technique because Alfred Hitchcock is credited for first using it in the film 'Vertigo'. Here's an example of it from the movie 'Goodfellas'...starting at 0:28 of the clip, when they sit down in the booth, watch the perspective of the background outside the window change as the foreground stays the same.

[i speak in math]

Long focal lengths compress the scene so objects far away appear relatively large and look like they are near the main subject.

Short focal lengths exaggerate the distance so far away objects look even farther away.

By changing focal length but keeping the main subject framed the same, you will change the perspective of other objects in the scene.

[PaulVI]

I was just lurking on the forum, opening up threads here and there.

You know, I've been wanting to know how this was done since I saw it in Jaws. (One of Roy Scheider's scenes during a panic on the beach.) Thanks for the great explanation, Bryan.

I think that in Jaws, the effect is used to convey Scheider's ill feeling that a shark attack is imminent. What is the purpose in the Goodfellas scene?

[Dangelica]

It shows the walls closing in and the air of paranoia building. Although I have to say the timing on the effect was a little off.

[dcclark]

Yes, it's just the effect of simultaneously zooming out while moving the lens closer to the subject. The result is that the subject (the front bottle) stays the same size, but the field of view widens to include more of the room -- so other objects appear smaller. It's a simple and pretty neat effect. You can replicate it with a zoom lens by doing what I described in the first sentence.

[Raoul Isidro]

Foreshortening.

[freybear3]

pretty neat, thnx for sharing