Photopic vision
Photopic vision is the
The human eye uses three types of cones to sense light in three bands of color. The biological pigments of the cones have maximum absorption values at wavelengths of about 420 nm (blue), 534 nm (bluish-green), and 564 nm (yellowish-green). Their sensitivity ranges overlap to provide vision throughout the visible spectrum. The maximum efficacy is 683 lm/W at a wavelength of 555 nm (green).[1] By definition, light at a frequency of 5.4×1014 hertz (λ = 555.17. . . nm) has a luminous efficacy of 683 lm/W.
The wavelengths for when a person is in photopic vary with the intensity of light. For the blue-green region (500 nm), 50% of the light reaches the image point of the retina.[2]
Most older adult humans lose photopic spatial contrast sensitivity. Adults in their 70s tend to require about 30–60% more contrast to detect high spatial frequencies than adults in their 20s.[3]
The human eye uses scotopic vision under low-light conditions (luminance level 10−6 to 10−3.5 cd/m2), and mesopic vision in intermediate conditions (luminance level 10−3 to 100.5 cd/m2).
See also
- Adaptation (eye)
- Candela
- Cone cell
- Contrast (vision)
- Mesopic vision
- Night vision
- Purkinje effect
- Photometry (optics)
- Photosensitive ganglion cell
- Scotopic vision
References
- ISBN 978-0-240-51417-8.
683 luminous efficacy.
- ^ a b "Molecular Expressions". Archived from the original on 2017-12-16. Retrieved 2013-03-18.
- S2CID 26003597.