Visibility Distance

Distance between you and your visible horizon.

Viewing Distance

Distance you are viewing the photo.

Visual Acuity

Clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain.  20/20 vision is 6/6 vision. At 20 feet or 6 meters, a human eye with nominal performance is able to separate lines that are one arc minute apart (equivalent to lines that are spaced 1.75 mm apart). Learn more on Wikipedia.

Vertical Angle of View

Angle of view  measured vertically (from the top to bottom of the frame).

Vertical Field of View

Field  of view measured vertically (from the top to bottom of the frame).

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