# Same runner, same field. Which run is longer?

- Series: [How Cameras](https://miu.fm/howcameras.md)
- Premieres: 2026-11-03
- Page: https://miu.fm/howcameras/same-runner-same-field-which-run-is-longer

## Story

Same runner, same field. Which run is longer?

Both are the same run, filmed at once: the top with a wide 16 mm lens up close, the bottom with a long 100 mm lens from 20 metres back, so she ends the same size in both.

Every picture has one spot where your eye sees exactly what the lens saw. On a phone screen about 15 cm tall, the top shot's spot is about 7 cm from the glass. In 2012, Emily Cooper, Elise Piazza and Martin Banks at UC Berkeley found that people don't look for it: change the lens, and they barely move (about 20 percent, against the 614 percent the lenses called for). Too far from a wide picture and its depth stretches; too close to a long one and it flattens. That, they argue, is why 50 mm feels natural on a print. A phone sits about 30 cm away, so for small screens they suggest longer lenses.

Their tests were small: five to eleven people each.

The field, the runner and the cameras are our own models, built and lit in code.

Bring your phone close to the top run. Does the field settle?

Source: Cooper, Piazza and Banks, Journal of Vision (2012), "The perceptual basis of common photographic practice".
Music: our own, played on GarageBand instruments. Sounds: made by us.

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