Cones function well in brightly lit surroundings, perceive colour and much detail.
Rods are far more sensitive than cones, giving night vision with the pupils wide open. Rods do not distinguish colours or see fine detail. Both rods and cones respond to a wide range of colours, but rods are very insensitive to red light. Rods respond to various colours, but give a sensation only of black, grey or white. Rods and cones are distributed non-uniformly across the retina.