No part. That is detected in the brain.
Quickest in the occipital area but there are other nodes near the optic cyasm.
See "visual systems" in Wikipedia.
Magnitude refers to a star's brightness.
photographs use to measure the brightness of a star
A lux meter is a device that measures surface brightness.
lumen
An adaptometer is an optometric instrument which measures the threshold of brightness that can be detected.
Bright is an adjective.
Photoreceptor
depends on the strength of your lens
the brightness hurts your eye rods
They are for seeing, but they can only see the brightness of things.
it refers to the brightness of a light source as it appears to the eye
The Danjon scale, named for Andre-Louis Danjon measures the relative brightness of the moon during a total lunar eclipse.