# What is the equivalent of shutter-speed in Human eye? Tags: vision - Score: 6 - Views: 18525 - Answers: 3 - Answered: yes - Asked by: laggingreflex (981 rep) - Asked: 2013-10-03 - Edited: 2013-10-03 - Site: biology ## Question I just learned that in video cameras, every frame of the video has its own shutter speed. And I know how frame-rate in human eye works out, well, not completely, hence the question. http://en.wikipedia.org/wiki/Frame_rate The human eye and its brain interface, the human visual system, can process 10 to 12 separate images per second, perceiving them individually. How much (or what is the equivalent of) shutter-speed in those individual images? ## Answers ### Answer by shigeta (score: 4 [ACCEPTED]) The light receptor of the eye is a protein called Rhodopsin. To me the equivalent of shutter speed for the eye is the (de)sensitization of rhodopsin by phosphorylation. The brighter the light, the more sites on rhodopsin are phosphorylated, diminishing the intensity of the signal coming from the photo receptor via the transducin G protein that conveys the visual signal onward. This process takes a few seconds, but then it's possible to see when stepping

iven by detector array C to F is required. All of these detector arrays provide a Yes-No-Yes response and thus allow the discrimination of the two lines. Figure 1 Detector array C and beyond allows the detection of the two lines. In the temporal domain, the same principle applies, except now the stimulus is separated in time ( Fig. 2 ). The separation between the two lines is in the temporal domain (two flashes are delivered) after a time interval t . The detector array now has different temporal integration times. For example, detector A integrates over time = t , whereas detector array B has an integration time of time = 0.5 t , array C, time = 0.33 t , and so on. Because of the shorter integration time for detector array C and beyond, such an array will be able to discriminate the two flashes that are separated by an interval of t . Figure 2 Speed of integration allows the detection of intermittent stimuli. Detector arrangement C and beyond allows discrimination of the stimuli over time. To detect a flash of light one after the other, an appropriate integration time is required ( Fig. 3 ). The period of integration is up to 0.1 seconds or 100 ms (for rods) and 10 to 15 ms for cones. The advantage of long integration time is that under limited light level conditions, a threshold will be reached, whereas when light levels are not limiting (cone or photopic vision), a short integration time is preferable to improve temporal resolution. Figure 3 Flashes of light are presented to the eye. (a) With a short integration time, the flashes are detected. (b) No flashes are perceived (that is, the stimulus appeared as one bright flash) with a long integration time. Temporal integration time is related to temporal summation. Temporal summation refers to the eye's ability to sum the effects of individual quanta of light over time. However, temporal summation only occurs within a certain period of time, called the critical duration or critical period. According to Bloch's law o