Lensatic Compasses seem to be priced from $5 to $100 USD. What features should I look for when buying one?
Lensatic Compasses are often used by the military, because the are:
- Stealthy (more on this)
The things that I would look for in a lensatic compass are:
- Solid outer casing
- Sighting guide with thin slot or notch
- Compass latching cover.
- Electrically buffered needle
- Some lensatic needles are buffered with oil, which can leak.
- Radioactive "Tritium" powered illumination
- Do Not use a compass with Radium
- Easy to read bezel for night time bearings and triangulations.
One of the great advantages to the lensatic compass is their use in night time navigation. The compass bezel is illuminated with a radioactive isotope. All modern lensatic compasses use Tritium, older compasses used to use Radium, but their use was linked to cancer, so don't use them.
The radioactive tritium particles are low energy beta particles and are not harful for external use, (they cannot pass through clothing or skin). As long as you don't swallow them you are fine.
The reason for the illumination is so that the compasses can be used without any external light source. The military, especially special forces, love this. It allows for "dark" navigation.
All radioactive isotopes have a half life. And Tritium's is 12 years, so in 12 years your compass will be half as bright as it is the day you bought it, then 12 years later, another half life. And so on.
Links to other information...