Recently, I showed a friend who said she wanted to enjoy the wilderness more my metal lensatic compass. It’s only one type of compass that a person can use to find out where they are or to plot a course. I put the lensatic compass in her hands and she had no idea how to hold it. That was no surprise to me because the first time I picked up one I had no idea which end was the front and which the back. So even before you can use a lensatic compass to take bearings or directions, you have to know its parts and how to hold it.
Revealing the Sections
The lensatic compass gets its name from the fact that to read its floating dial you have to look through the magnifying lens of the compass. Would- be users of the compass need to be able to identify its three sections of which the lens in the rear of the compass is one.
Since the lensatic compass is a folding instrument, open it to reveal its three sections. Usually the first step to unfolding it is to lift the thumb loop up and back. The thumb loop also locks the cover, which is the front section of the compass. The cover protects the dial and also houses the sighting wire.
The base, which is the mid -section of the compass, is the third section. The floating dial and the thumb loop, which is attached to the base, are in this section. If the compass has a bezel ring, which can be rotated by hand to take bearings in poor visibility, it often encircles the top of the base.
Floating Dial
The floating dial has the index line, which is the longest fixed line on the compass. The floating dial also has a magnetic arrow that always points to magnetic north. It also has east and west indicators. Some dials also have an indicator marked south. South is at 180 degrees, east at 90 and west at 270. Many lensatic compasses also have a scaled straightedge on the left side to assist in drawing lines and measuring distances on a map.
The outer edge of the floating dial has two sets of numbers. The outermost set is often in a scale called mils, used by military gunners to locate targets. With mils, the face of the compass is usually divided into 6400 mils, notes the book “Maps & Compasses: A User’s Handbook” by Percy Blandford. Some dials use the grads system for the outermost numbers, Blandford notes, the dial being divided into 400 grads. The inner set of numbers is in degrees, ranging, of course, from 0 to 360.
Two Ways of Holding
The methods of holding a lensatic compass are the centerhold and compass-to-cheek. The centerhold method works with all compasses whereas the compass-to-cheek method works only with the lensatic compass when the view of the object on the terrain you’re sighting is unobstructed. However, the compass-to-cheek method is the more accurate of the two.
Centerhold Method. Open the compass fully so that the base and the cover form a 180-degree angle. Pull the lens up to at least a 45-degree angle so that the dial floats, and make sure you can read the numbers on the floating dial. Place the thumb of your dominant hand through the thumb loop. Put the index finger of that hand along the right side of the compass and rest your next two fingers under the base. Put the thumb of the other hand along the left side of the compass. As you’re reading the dial, hold the compass somewhere between your chin and waist and point it and your body at the object.
Adjust the lens so that you can read the numbers. Take the bearing as your hold the compass steady, have the object centered in the notch in the lens section and the sighting wire in the cover, and after the dial has stopped floating. Using the centerhold method, the user can rotate the bezel ring if necessary.
Chin-to-Cheek Method. Open the compass. Position the cover at 90 degrees to the dial. Using this method, the compass is held at face level. Adjust the lens and center the object as in the centerhold method. Take the bearing.