manual

56
The effects of light on the retina create optical illusions.
Diagram of the eye
lens
pupil
iris
cornea
fovea: area of the retina where
the clearest image is formed
retina
The dark blotches in the
white corners are due to
how the light hits the most
sensitive and central part of
the retina, the fovea.
When your view encompasses
the whole picture, the blotches
are visible. When you
concentrate on a single white
corner, you don’t see the dark
blotch any more.
Detail of
a corner