Nikon Scopes
A telescopic sight, commonly called a scope, is a
device used to give additional accuracy using a point of
aim for weapons such as firearms, airguns and crossbows.
Scopes are classified in terms of the optical
magnification and the objective lens diameter, e.g.
10×50. This would denote 10 times magnification with a
50 mm objective lens. In general terms, larger objective
lens diameters are better (collect more light and give a
wider field of view), the magnification power should be
chosen on the basis of the intended use. There are also
adjustable objectives sights where the magnification can
be changed.
Scopes come with a variety of different reticles,
ranging from the traditional crosshairs to complex
reticles designed to allow the shooter to estimate
accurately the range to a target, to compensate for the
bullet drop, and to compensate for the windage required
due to crosswinds. A user can estimate the range to
objects of known size, the size of objects at known
distances, and even roughly compensate for both bullet
drop and wind drifts at known ranges with a reticle-equipped
scope.
There are two main types of reticles: Wire reticles
and etched reticles
Wire reticles are the oldest type of reticles and are
made out of metal wire. They are mounted in an optically
appropriate position in the scopes sight's tube. Etched
reticles are images of the desired reticle layout that
are etched on an optic element. This optical element
(lens) with the etched reticle is then mounted in the
scopes sights tube as an integrated part of the optics
chain of the sight. When backlit through the ocular a
wire reticle will reflect incoming light and not present
a black contrast reticle. An etched reticle will stay
black if backlit. Etched reticles are by most considered
to be a more refined solution and offer greater reticle
lay out flexibility. Because of this some manufacturers
can provide client designed custom reticles on special
order. In the more expensive and high end contemporary
scope sights etched reticles dominate the market. In
cheaper scope sights wire reticles are still often
mounted to avoid a rather specialized and costly
production step.
The reticle may be located at the front or rear focal
plane (First Focal Plane (FFP) or Second Focal Plane (SFP))
of the scope sight. On fixed power scope sights there is
no significant difference, but on variable power scope
sights the front plane reticle remains at a constant
size compared to the target, while rear plane reticles
remain a constant size to the user as the target image
grows and shrinks. Front focal plane reticles are
slightly more durable, but most American users prefer
that the reticle remains constant as the image changes
size, so nearly all modern variable power scope sights
are rear focal plane designs.
Either type of reticle can be illuminated for use in
low light conditions. With any illuminated reticle, it
is essential that its brightness can be adjusted. A
reticle that is too bright will cause glare in the
operator’s eye, interfering with his ability to see in
low-light conditions. This is because the pupil of the
human eye closes quickly upon receiving any source of
light. Most illuminated reticles provide adjustable
brightness settings to adjust the reticle precisely to
the ambient light.
A scope sight can have several adjustment controls:
- Focusing control at the ocular end of the sight
- meant to obtain a sharp picture of the object and
reticle
- Elevation or vertical adjustment control of the
reticle
- Windage or horizontal adjustment control of the
reticle
- Magnification control - meant to change the
magnification by turning a ring that is generally
marked with several magnification power levels
- Illumination adjustment control of the reticule
- meant to regulate the brightness level of the lit
parts of the reticles crosshairs
- Parallax compensation control
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