4.1.2 Rubber fold-down eyecups
This is a long eye relief binoculars. It allows the eyeglasses wearer to see a normal image without
taking off glasses. These convenient eyecups fold down for using with glasses and fold up for using
without glasses. lightly press eyecups, can fold down the eyecups easily.
4.1.3 Focusing
In order to get a clear image you must focus the binoculars. This model has two individual diopter
adjustment rings on each telescope for you to adjust the optics to your individual eyes, you will need to
adjust each eyepiece. After placing the binocular at your eyes and view an object, you will need to close
your left eye. Rotate the right diopter adjustment rings until the object image appears sharp and clear in
your right eye opening. Then open you left eye and close right eye, rotate the left diopter adjustment rings
until the object image appears sharp and clear in your left eye opening. Then can get a perfect viewing.
To focus on other objects, repeat the same operation.
If you share your binoculars with another person note the diopter index mark setting at the base of
the eyepieces first. Then you can simply return the eyepieces to those setting when you next use (with out
adjustments) the binoculars to view an object at the same distance.
4.2 How to use the reticle and calculator dial as measuring devices
4.2.1 What is View Angle
View Angle of an object (or outboard of two objects) is the angle between the rays from telescope to
its edges. Usually, this angle is measured at horizontal or vertical direction, and define it Horizontal View
Angle and Vertical Angle.
A mil’s reticle (fig.3) that has horizontal or vertical scale can measure the View angle of an object.
4.2.2 How to measure the Horizontal View Angle
4.2.2. A.
When the Horizontal View Angle is smaller than the horizontal scale range (-40
～
+40 mils)
inside the binoculars, aim one edge of the object at a horizontal scale line (the center or the outmost line
are selected according to the image size of object usually) and read its value. Then read the value of the
scale at which another edge was located. Plus this two value, the sum value is the measured Horizontal
View Angle. As shown in fig 4, the Horizontal View Angle of the target (sailboat) is 2 decade miles (20
miles), and the Horizontal View Angle between the targets (p-p) is 8 decade miles (80mils).