Both cameras and the human eye use lenses to focus light ... The rods see the shapes of things, picking out black, white and shades of grey… and the cones see colours: red, green and blue ...

Seeing through one eye or many, in technicolour or black and white ... But because rod cells only have a single light-sensitive pigment, at night we see in shades of grey. Geckos, on the other hand, ...