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The pupil of the human eye can range in size from 2 mm to over 8 mm to adapt to the environment. The human eye can detect a luminance from 10 −6 cd/m 2, or one millionth (0.000001) of a candela per square meter to 10 8 cd/m 2 or one hundred million (100,000,000) candelas per square meter.
A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. [9] Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better ...
Peripheral vision of the human eye. Vision span or perceptual span is a controversial concept referring to the angular span (vertically and horizontally), within which the human eye has sharp enough vision to perform an action accurately (reading or face recognition). The visual field of the human eye spans approximately 120 degrees of arc. [1]
For example, binocular vision, which is the basis for stereopsis and is important for depth perception, covers 114 degrees (horizontally) of the visual field in humans; [7] the remaining peripheral ~50 degrees on each side [6] have no binocular vision (because only one eye can see those parts of the visual field). Some birds have a scant 10 to ...
Classical image of the shape and size of the visual field [28]. The outer boundaries of peripheral vision correspond to the boundaries of the visual field as a whole. For a single eye, the extent of the visual field can be (roughly) defined in terms of four angles, each measured from the fixation point, i.e., the point at which one's gaze is directed.
Under such "typical" dark sky conditions, the naked eye can see stars with an apparent magnitude up to +6 m. Under perfect dark sky conditions where all light pollution is absent, stars as faint as +8 m might be visible. [4] The angular resolution of the naked eye is about 1 ′; however, some people have
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. [3]
The other limit to the eye's accommodation range is the far point. A normal eye is considered to have a near point at about 11 cm (4.3 in) for a thirty year old. [1] The near point is highly age dependent (see accommodation). A person with hyperopia or presbyopia would have a near point that is farther than normal.