Basic Accuracies
The basic accuracies of the human eye are:
- Quick autofocus from distances of 10 cm (young people) to 50 cm (most people 50 years and older) to infinity.
- Angular resolution: about 4 arcminutes, or approximately 0.07°, which corresponds to 1.2 m at a 1 km distance.
- Field of view (FOV): simultaneous visual perception in an area of about 160° × 175°.
- Faint stars up to +6.5 magnitude under a modern dark sky.
- Photometry (brightness) to ±10% or 1% of intensity - in a range between night and day of 1:10,000,000,000.
- Symmetries of 10-20' (3–6 m per 1 km), see the measurements of Tycho Brahe and the Egyptians.
- Interval estimations (for example at a plan on paper) to 3-5%.
- Unconscious recognizing of movement (that is "alarm system" and reflexes).
Visual perception allows a person to gain much information about his or her surroundings:
- the distances and 3-dimensional position of things and persons
- the vertical (plumb line) and the slope of plain objects
- luminosities and colors and their changes by time and direction
Read more about this topic: Naked Eye
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