The CIE 1951 scotopic luminosity function. The horizontal axis is wavelength in nm.

Scotopic vision is the vision of the eye under low light conditions. The term comes from Greek skotos meaning darkness and -opia meaning a condition of sight.^[1] In the human eye cone cells are nonfunctional in low light - scotopic vision is produced exclusively through rod cells so there is no color perception. Scotopic vision occurs at luminance levels of 10^-2 to 10^-6 cd/m². In other life forms, such as the Elephant Hawk-moth (Deilephila elpenor), advanced color discrimination is displayed. ^[2]

Mesopic vision occurs in intermediate lighting conditions (luminance level 10^-2 to 1 cd/m²) and is effectively a combination of scotopic and photopic vision. This however gives inaccurate visual acuity and colour discrimination.

In normal light (luminance level 1 to 10⁶ cd/m²), the vision of cone cells dominates and is photopic vision. There is good visual acuity (VA) and colour discrimination.

In scientific literature, one occasionally encounters the term scotopic lux which corresponds to photopic lux, but uses instead the scotopic visibility weighting function.^[3]

[edit] See also

• Adaptation (eye)
• Purkinje effect
• Averted vision
• Photopic vision

[edit] References

1. ^ scotopia at dictionary.com
2. ^ Scotopic colour vision in nocturnal hawkmoths
3. ^ Photobiology: The Science of Light and Life (2002), Lars Olof Björn, p.43, ISBN 1402008422

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