Short Focal Toy Story
August 7, 2013 10:15 AM   Subscribe

How come short focal length makes supposedly real things look like tiny toys?

Or not, I got it off Tumblr after all. Please explain it to me like I'm a short-focal-year-old.
posted by moody cow to Technology (10 answers total) 13 users marked this as a favorite
The technique being used for those is called Tilt-Shift Photography.

I do not understand how it works either, but here is the wikipedia entry, which I'm sure will lead you to the knowledge you seek.
posted by sparklemotion at 10:21 AM on August 7, 2013

Its not so much short focal length (which gives you a wide field of view) as it is using tilt-shift lenses (or simulating them in an image editor) for miniature faking.
posted by TedW at 10:23 AM on August 7, 2013

It's not a short focal length causing that effect, it's a shallow depth of field.

When we look at toys or miniatures, we are usually up close to them, and at short distances, we have a very shallow depth of field. This means only a thin sliver of distance from our eyes is in focus at any one time. The rest is out of focus.

So when you take a photograph of real things, from an elevated point of view, using a wide aperture on the camera - which produces a shallow depth of focus - the image reminds us of looking at a toy or miniature - because the photo mimics the conditions under which we'd view such toys.

Notice in your example photos that the top and bottom are out of focus, and only a small part is in focus.
posted by gyusan at 10:23 AM on August 7, 2013 [12 favorites]

To add on to what gyusan is saying- the reason this doesn't happen when looking at large distances in real life is that at some point, focus becomes "infinite", and all things past that point are in focus, unless you're nearsighted. The fact that this doesn't happen in the tilt-shift contributes strongly to the illusion.
posted by thewumpusisdead at 10:28 AM on August 7, 2013 [4 favorites]

Those example movies don't even demonstrate shallow depth of field; they're just blurring the top and bottom of the images. For example, in the first, the tops of the poles next to the sharply-focused terminals are blurred even though they're in the same focal plane; in the second, the building at the right blurs as it rises along with the more distant background next to it.
posted by nicwolff at 10:58 AM on August 7, 2013 [1 favorite]

They're also speeding up the motion, which gives the effect of tiny lightweight objects that can turn quicker, accelerate quicker, etc., than real ones can. Perhaps an airliner can move into a gate that fast, but it wouldn't be safe.
posted by randomkeystrike at 11:03 AM on August 7, 2013

The reason why it works:

1) Pictures of genuinely small objects generally have a very short depth of field (because the camera is (usually) very close to the thing being photographed, so objects that are closer to or farther from the camera are farther from the focal point, proportionally, than they would be if the camera were farther away)
2) People look at a lot of photographs, and have learned to associate "short depth of field" with "that thing must be tiny" because usually it is.
3) Artificially creating a short depth of field (or even something that vaguely looks like a short depth of field) therefore creates the impression of tininess.

Someone who had never seen a photograph before would not interpret tilt-shift as "small", they'd just wonder why the top and bottom of the frame are blurry.
posted by ook at 11:45 AM on August 7, 2013 [5 favorites]

Contributing to the effect in the examples you link to, for some people at least, is the noticeably low frame rate: old folks like me will unconsciously associate that with stop-motion photography, which also tended to use small models instead of life-size things -- because that is what we used before all these newfangled computers made real special effects obsolete.

(It's kind of amazing how much of our perception is colored by the media representations of reality rather than the real thing. I still catch myself looking for the bokeh blur every time I drive in the rain at night, or looking for looping tile boundaries on the surface of the ocean...)
posted by ook at 12:55 PM on August 7, 2013

I think you're wrong, ook – the association of "short depth of field" with "small close objects" is just as true of the human eye as it is of a camera, since in normal light the aperture of the iris of the eye is relatively large.

Try it now: look past a object one foot away at one two feet away, then at the closer object, and see how blurry the object you're not focused on looks. But if you look at an object 100 feet away the background is sharp too.

So tilt-shift works not by making you think "wow this looks like pictures I've seen of little things!" but by making you think "wow, this is what little things looks like!" – and would work even if you'd never seen a photo before.
posted by nicwolff at 1:48 PM on August 7, 2013

Response by poster: Thanks for your explanations and the interesting discussion.
posted by moody cow at 4:49 AM on August 8, 2013

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