Binocular AFOV Calculator
Nikon ISO 14132-1:2002 Standard Method
AFOV Calculator
Nikon ISO Standard Formula
tan ?' = G × tan ?
Apparent Field of View: 2?'
?': Half apparent field of view angle
G: Binocular magnification
?: Half real field of view angle
Understanding Binocular Fields of View
Real Field of View
Real field of view is the angle of the visible field seen without moving the binoculars,
measured from the central point of the objective lens. A wider field of view is advantageous
for locating fast-moving subjects like birds or for finding celestial objects in astronomy.
Apparent Field of View
Apparent field of view is the angle of the magnified field when looking through binoculars.
A larger apparent field provides a wider view even at high magnifications. Nikon uses the
ISO 14132-1:2002 standard for calculation, where apparent fields wider than 60° are
classified as wide field of view.
Field of View at 1,000 Meters
This represents the width of the visible area at 1,000 meters distance. For example,
with 8×42 binoculars having 7.0° real field of view:
Field of view at 1,000m = 2 × 1000m × tan(7.0° ÷ 2) = 122m
AFOV Classification Standards
| Classification | Apparent FOV | Traditional Method | Typical Use |
|---|---|---|---|
| Standard | < 60° | < 65° | General purpose |
| Wide | 60° - 70° | 65° - 75° | Bird watching, sports |
| Extra Wide | 70° - 80° | 75° - 85° | Astronomy, nature |
| Ultra Wide | > 80° | > 85° | Premium astronomy |