When selecting a rifle scope, it's a good idea
to be familiar with the terms listed below.
Combining this knowledge with your preferences
will help you select a rifle scope that you'll
be satisfied with for years to come.Magnification
The numbers on a scope represent the power, or
magnification, and the objective lens size. The
first set of numbers represent the power of the
scope. Some scopes have a variable magnification
range, though. For example, a scope that is
noted as 3 - 9x has the ability to change from 3
power up to 9 power.
Fixed magnification scopes have their
magnification fixed at one power.
The last number noted on a scope represents the
size of the objective lens in millimeters. For
example, 3 - 9 x 50 represents a scope with
variable 3 - 9 magnification and a 50 millimeter
lens.
Objectives
Larger objective lenses gather more light,
resulting in a clearer view and better
resolution. They do not increase magnification.
Exit Pupil
The exit pupil should be as large as the human
eye under the same conditions. The pupil changes
with change in the amount of light, making it
large in low light and small in bright light. To
compute the exit pupil size, divide the
objective lens size by the magnification of the
scope.
Field of View
Field of view in rifle scopes is expressed as
the width of the viewing area as seen at 100
yards. Lower magnification scopes will have a
larger field of view.
Optic Quality
Uncoated lenses will allow over 50% of the light
to be reflected. Coated lenses will allow better
light transmission (i.e., less light being
reflected, more being absorbed), resulting in
better clarity. A single coating on a lens means
the scope is fully coated. The scope is
considered multi-coated if additional lenses are
coated. If all lenses are coated with more than
one layer, the lenses are considered fully
multi-coated.
Parallax
Parallax is the distortion seen when viewing an
object at a distance at which the scope is not
sighted in for.
Windage
The windage adjustment alters the left to right
movement of the scope.
Elevation
The elevation adjustment alters the up and down
movement of the scope.
Rings and Mounts
A good set of rings and mounts are needed to
secure any rifle scope. Loose or poor fitting
rings will cause the point of impact to vary.
Being familiar with these terms will result in a
more satisfied purchase and you will have a
quality scope that will serve you for years to
come. |