  The physiology of the dark adaption process of the eye is revisited from an
astronomical point of view.
  A new method for the magnitude estimation of a star is presented. It is based
upon the timing of the physiological cycle of the rhodopsin during the eye dark
adaption process. The limits of the application of the method are discussed.
This method is suitable for bright stars as Betelgeuse, Antares or Delta
Scorpii or stars at the limiting magnitude observed with a telescope.

Instrumentation and Methods for Astrophysics;Medical Physics