Basic Laser Rangefinder Calibration    Edward Frank
   Dec 13, 2006 17:43 PST 


When someone purchases a new laser rangefinder, they should check on how
well it is calibrated. It is a fairly simple procedure to see how
accurately the laser is measuring.   

1) Make sure the laser works by putting in the battery and try it out
measuring a few distances around your home. Check to make sure you are
using the correct scale.

2) Next try to find some place where you can measure longer distances.
Typical distance you will be measuring for trees will be 40 to 100
yards. It is better to check the calibration at the distance you
actually will be measuring with it.   A local football or baseball field
is a good place to go.

3) You will need a long tape, the longer the better. If it is 50 feet
for example, you will need to stretch out several lengths of the tape to
check the distances.

4) Lay the tape out on the ground or pick a target and carry something
to mark your position. The target should be something relatively flat
from which you can get a good reflection and not be obscured by brush or
other intervening objects.

5) As you move away from the target you want to measure the distance at
the point the laser changes from one number to the next larger one.
Either read the tape at that point or mark the point and measure it
later. When measuring the tree top or bottom you move back and forth to
get to the exact point the number on the laser changes from one to the
other.   Measuring at the point where the numbers changes on the
instrument will be repeatable and accurate to probably less than one

6) You should find it gives a good reading of distance when used in this
way. Often you will find the factory settings to be close enough that
you may need not to use any calibration corrections for distance. If
the laser is off by a half a yard or a yard or more, you should consider
returning it to the factory for recalibration.

**** If you are measuring set distances on a tape with a laser, then
you are doing it backwards. This will result in measurement errors of
up to 3 feet.

Edward Frank