photopic$60460$ - traduzione in
![The 1931 CIE photopic [[luminosity function]]. The horizontal axis is wavelength in nm.](https://commons.wikimedia.org/wiki/Special:FilePath/CIE 1931 Luminosity.png?width=200 "The 1931 CIE photopic [[luminosity function]]. The horizontal axis is wavelength in nm.")
![A 2019 [[American Silver Eagle]] [[bullion coin]] with a fineness of 999 ('three nines fine'), together with a [[Walking Liberty half dollar]] with a fineness of 900 ('one nine fine').](https://commons.wikimedia.org/wiki/Special:FilePath/2019 American Silver Eagle and 1943 Walking Liberty Half dollar side by side.jpg?width=200 "A 2019 [[American Silver Eagle]] [[bullion coin]] with a fineness of 999 ('three nines fine'), together with a [[Walking Liberty half dollar]] with a fineness of 900 ('one nine fine').")
![Example of a container used for collecting 24-hour urine samples. This particular container is free of [[trace metal]]s to allow for accurate measurement of these substances in urine.](https://commons.wikimedia.org/wiki/Special:FilePath/Trace metal-free 24 hour urine container.jpg?width=200 "Example of a container used for collecting 24-hour urine samples. This particular container is free of [[trace metal]]s to allow for accurate measurement of these substances in urine.")
![agar]], which changes colour based on the bacterial species present](https://commons.wikimedia.org/wiki/Special:FilePath/Urine cultured on Oxoid Brilliance UTI Agar plate.jpg?width=200 "agar]], which changes colour based on the bacterial species present")
Definizione
Wikipedia
Photopic vision is the vision of the eye under well-lit conditions (luminance levels from 10 to 108 cd/m2). In humans and many other animals, photopic vision allows color perception, mediated by cone cells, and a significantly higher visual acuity and temporal resolution than available with scotopic vision.
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). 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.
Adaptation is much faster under photopic vision; it can occur in 5 minutes for photopic vision but it can take 30 minutes to transition from photopic to scotopic.
Most older adult humans lose photopic spatial contrast sensitivity. Adults in their 70s require about three times more contrast to detect high spatial frequencies than adults in their 20s.
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).
