The Limits Of Human Vision

Adam Hadhazy, BBC:

A million colours; single photons; galactic realms quintillions of miles distant – not bad for the blobs of jelly in our eye sockets, wired to a 1.4 kilogram sponge in our skulls.

To add a bit of context:

  • Photon wavelengths: about 380 to 720 nanometers
  • Colors: about 1,000,000 (100 color shades per cone x 3 cones)*
  • Sensitivity: one photon
  • Distance: one photon (as long as a photon reaches our retina)
  • Visual Acuity: 120 pixels per degree of arc (fingernail at arm’s length with 60 horizontal and 60 vertical lines)

Our visual system is quite a remarkable design.

* Tetrachromats are people who have an extra fourth cone cell allowing them to perceive 100 million colors.