4.2.3.B.
when the Vertical View Angle is larger than the vertical scale range (80 mils), it can be measured
in steps and the angle can be obtained by summing up the value of each step. (The process will be similar
to the one that is discussed in the linear measurements in 4.2.2 B above.)
4.2.4 How to use the reticle to measure distance
The distance measurement of a target can be calculated by using the mil reticule. (Fig 7)
The formula of distance measurement: L
（
km
）
= H (m)/ω
L
— the distance between the observer and the object (km)
H
— the height of the object (m)
ω — the View angle of the object measured with the reticule of binoculars (mil).
When measure the distance, first, estimate the width or height of the object, then measure the View
Angle of the object. According, you can calculate the distance between the observer and the object using
the formula.
For example:
There is an adult whose height is 1.70m. (H = 1.70m)
The Vertical View Angle of the adult is 4 decade mils (40mils)
L = H/
ω = 1.7/40 = 0.0425km = 42.5m
Therefore: the distance between the observer and the adult is 42.5m.
4.2.5 How to use the Calculator Dial
The Calculator Dial can be used to determine distance quickly and easily without calculation. The
Calculator Dial inclu
des a triangular Angle Index Mark marked “ANGLE”, a rotational Active Ring and a
Fixed Scale marked “DISTANCE”. There are two scales in the Active Ring, one above is View Angle scale
and another is Size Scale marked “OBJECT SIZE”.
First, measure the View Angle value of an object, and rotate the Active Ring and place this value at
the Angle Index Mark. Then, find the division indicating the size of the object, it indicate a point at the
Fixed Scale, look at the Fixed Scale, the distance is shown at that point on the Fix Scale.
For example: See fig 8.You observe a light house and its measured Vertical View Angle is 6 decade
mils, you need rotate the Active Ring and place the division marked “6” in the View Scale at the Angle
Index Mark. Its assuming high is
12m, the division marked “12” in the Size Scale point the division marked
“200” in the Fixed Scale. This tell us that the lighthouse’s distance is 200m from us.
The Size Scale and Fix scale of Calculator Dial are in a “ratio” to each other. When you observing
object is too large or too small, you can zoom it tenfold or discretionarily, and zoom measuring result in the
same way. Thus, you can get more convenience, specially, when you aren’t familiar with diversified units.