Western Hunting Journal, Sneak Peak WHJ_Short | Page 29

Parts of a Rangefinder
Small, powerful processors and advanced components
have allowed modern rangefinders to become incredibly
accurate, compact and easy to carry.
EYEPIECE LENS
ROOF PRISM
LCD
As I watched the bull feed out of the trees into the
open hillside, I didn’t have to estimate the distance or
guess what adjustment to make. A quick check with
my rangefinder told me everything I needed to know.
He took two more steps; I checked again to confirm
the reading, quickly referenced the ballistic informa-
tion for my rifle, and fired a single shot. The bull never
took another step.
Without question, rangefinders play one of the
most important roles in consistently placing shots
on target, and when it comes to hunting, bullet place-
ment is the key factor in ensuring swift, ethical kills.
Knowing the exact distance to targets allows for pre-
cise adjustments and compensation, or perhaps rul-
ing out a shot all together. I can say with one hundred
percent certainty, regardless of how large the bull
was, had I not known the distance in that situation,
I would have never even attempted a shot. The risk of
potentially wounding an animal due to a misjudged
shot is simply too great a risk to take.
What to Look For
OBJECTIVE
LENS
LIGHT-EMITTING
LASER DIODE
LIGHT-EMITTING
PHOTODIODE
LIGHT-RECEIVING
LENS
Beam Divergence Over Distance
Similar to the beam of a flashlight, the beam divergence
of the laser will spread over distance, affecting
the ability to accurately read targets. Units
1,000 yds
rated for longer ranges will have less
divergence, allowing accurate
readings at great distances and
500 yds
with less interference from
the target surroundings.
1,500 yds
While few will argue the importance of a quality
rangefinder, the myriad of styles, features and options
available can leave many feeling overwhelmed and
confused. Let’s get started with a quick breakdown of
what to look for, and maybe also dispel a few com-
mon misconceptions.
Typical rangefinders work by emitting a class 1 (in-
visible) laser which reflects off the desired target and
the returning signal is read by high speed sensors in-
side the unit. Using the known speed of light, proces-
sors in the unit can then calculate the time it took to
receive the return signal, and then convert to distance
traveled. The process seems relatively simple, yet it is
anything but. reflected signals, in turn produce faster and more ac-
curate readings.
Processor Size of Laser Beam
Just like computers or phones, some units employ
processors that are faster and more powerful than
others. When it comes to rangefinders, this means
some units can compute more readings, faster read-
ings, and calculate faster data than other units. Early
generation rangefinders often based readings off a
single return signal, which often resulted in errone-
ous readings, whereas newer units commonly emit
pulses of signals that return more data back to the
unit allowing for tighter averaging calculations and a
much more accurate readout.
The key to getting an accurate readout is doing
your best to control what data is being sent back
to the machine. Looking at units in a store you can
quickly see a variety of aperture sizes. Generally,
larger apertures can better collect larger amounts of
Have you ever noticed how a flashlight beam on your
living room wall may be a small spot, but it can illu-
minate your neighbor’s house across the street? The
beam coming out of a rangefinder acts much the
same way. The divergence, or spread, of the beam
can vary greatly from one unit to another. Some units
will state what this may be, while it can be hard if not
impossible to find on others. Basically, as the beam
spreads over distance, it may be picking up readings
from objects that are not the target. When these read-
ings return along with the target readings, the unit
may average all the readings and give a false distance.
Sometimes, if the target is small enough, and there
is a lot of surrounding interference, you may not get
a target reading at all. Too tight of a beam can also
cause problems, as at...Subscribe to read more...
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