Editing Visible spectrum (section)

===Opsin absorption===
Each opsin has a [[spectral sensitivity]] function, which defines how likely it is to absorb a photon of each wavelength. The luminous efficiency function is approximately the superposition of the contributing [[Vertebrate visual opsin|visual opsins]]. Variance in the position of the individual opsin spectral sensitivity functions therefore affects the luminous efficiency function and the visible range. For example, the long-wave (red) limit changes proportionally to the position of the L-opsin. The positions are defined by the peak wavelength (wavelength of highest sensitivity), so as the L-opsin peak wavelength blue shifts by 10&nbsp;nm, the long-wave limit of the visible spectrum also shifts 10&nbsp;nm. Large deviations of the L-opsin peak wavelength lead to a form of [[color blindness]] called [[protanomaly]] and a missing L-opsin ([[protanopia]]) shortens the visible spectrum by about 30&nbsp;nm at the long-wave limit. Forms of color blindness affecting the M-opsin and S-opsin do not significantly affect the luminous efficiency function nor the limits of the visible spectrum.