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.
Cones are only in the center.
While in the periphery, the rods dominate. If light is needed, yet it is important to keep eyes dark-adapted, then use a red filter on the light. Rods are not sensitive to red light. This is the diameter of the bundle of light rays exiting toward the eye from the eye-piece of the binoculars. The pupil of the eye is about 7mm when fully dialated.