INTRODUCTION

The Lensatic compass differs from the type most hikers are familiar with, the traditional "orienteering" compasses. The Lensatic, a design preferred by military forces for its precision and durability, is designed to take hyper-accurate bearings for land navigation and directing artillery fire!

It is composed of four basic parts, the compass card (rose) itself, with housing, degree scale and rotating bezel; the sighting-wire unit/top cover; the thumb hook; and the lens for which it is named.
 

TO TAKE A BEARING/AZIMUTH

Open the top cover half-way, such that it forms a 90* angle with the compass card. Lift the lens arm up to roughly a 45* angle, and make sure the thumb hook is all the way to the bottom. Place your thumb into the hook for stability. Looking at the target Object, position the Sighting Wire in the middle of the Object. Move the lens up and down such that you can read the fine degree markings from the card without taking your eyes off the Object. Read the bearing in degrees, or if preferred, MILS.
 

TO SET A BEARING

Sight on your destination as above and note the bearing in degrees. Rotate the marking on the moving bezel into alignment with Magnetic North as indicated by the compass card. This allows you to orient yourself after traveling because you will rotate yourself so that the compass's Magnetic North aligns with the bezel's marking. Then, the bearing indicated through the sighting wire is the direction
you must travel to remain on course.
 

TO FOLLOW A BEARING

After orienting yourself as above, select a landmark in the distance and use that as a reference point while hiking. When the landmark is not visible, due to trees, clouds, etc., simply follow the bearing indicated on your Lensatic Compass. From time to time, you will want to confirm your direction by taking a new bearing to the landmark.
 

ORIENTEERING WITH THE LENSATIC

Orienteering with the Lensatic is not as simple as with purpose-build orienteering compasses, such as the Silva line, but it is not difficult, either. Most modern Lensatics feature a square case, one side ruled, so that you may use it to triangulate known Landmarks to your position. The built-in ruler is designed for military grid maps, but will work with USGS topo maps too, with a bit of arithmetic. As the Lensatic lacks a protractor, you must either bring one along--the military supplies a protractor for this purpose--or improvise using the compass card itself, which is nicely divided into degrees! O happy day!

For more information on using a lensatic compass and land navigation, http://landnavigation.org/ is a good site, with downloads galore of instruction.