Rangefinder, when you search on Google, there comes many results from laser rangefinder. They are mostly used for golf or short range distance.
But what we're going to talk about in this article is the rangefinder on binoculars. It is completely optical type.
They usually have a scale in the right field of view corresponding to the measurement, although it is not possible to directly read the distance value, but because of their purely mechanical way, in a way, is more suitable for the binoculars.
*Note while the rangefinder on the binoculars also requires batteries, they are for illumination use only.
How does optical rangefinder work?
There are actually systems for calculating the distances used in rangefinder cross binoculars and oscilloscopes. The simplest and most common method is to compare the scale or measurement mark on the marker in the binocular, monocular or oscilloscope field of view with a known size section or the entire object you are viewing. In military and hunting circles this is often referred to as the Mil-Dot marker and the formula for calculating the distance is called the Mil-dot formula.
Are rangefinder markers valid?
Yes, while they are not as accurate and fast as laser rangefinders in providing accurate values over short distances, they can give you a good idea and can be useful over long distances. Their accuracy depends on how well the user aligns the targets and, of course, how accurate they are in estimating the height or length of the targets. If you know the exact height of the targets and align them very carefully on the markers, they will be very accurate.
And considering that the battery-free operation makes the binoculars suitable for more environments, the matching compass can also provide an important role in navigation and outdoor use.
For USCAMEL hot sale binoculars with rangefinder and compass. There is an additional tool for easily getting the distant number.
How to use the calculator on your binocular to estimate distance
The Calculator Dial can be used to determine the distance quickly and easily without using the above calculation. The Calculator Dial comprises a rotational active ring showing a triangular "ANGLE" marking and affixed scale marked "DISTANCE". 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 values of an object, rotate the Active Ring and place this value at the angle index mark. Then, find the division indicating the size of the object, where the size meets the distance scale indicates the distance to the object.
For example: See fig.7. You observe a lighthouse and its measured Vertical View Angle is 60mils. Rotate the Active Ring and place the division marked "6" in the View Scale Angle index Mark. Its height is 12m, the division marked "12" in the Size Scale lines up with the division marked "200" in the the Fixed Scale.
This tell us that the lighthouse's distance is 200m from us.
Where the size of the observed object is outside the scale just divide the size of the object by a number that will bring your object size to within the scale and divide the View Angle by the same number. As the values are on a fixed scale ratio the resulting value on the dial will be correct. (There is no need to multiply out the result).