3.2.2 How to calculate the Horizontal View Angle of anobject
When viewing an object through the binoculars, line one edge of the object up with a point on the horizontal
scale line and read the value from where the other edge meets the horizontal scale.
In Fig. 2, the right edge of the sail boat is at zero and the left edge at 2, so the horizontal view angle is 20
miles. (1 on the scale = 10 miles).
Note : When the object is largerthan the scale: choose a midpoint,take the view angle of this point and multiply
by 2.
3.
How to calculate the Vertical View Angle of an object Use the same method as
than before but use the vertical scale.
4.
How to use the calculator on your binoculars to estimate distance The calculator dial comprises a
rational active ring showing a triangular "ANGLE" marking and a fixed scale marked "DISTANCE" (Fig. 3).
There are two scales in the Active Ring, the upper scale is View Angle and the lower is a Size Scale marked
"OBJECT SIZE". First, measure the View Angle value of an object, rotate theActive Ringand place this value at
theAngle Index
Fig. 2
9
Fig. 3