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Magnification is simply the degree
to which the object is enlarged. With a 7x35 binocular,
for example, the object appears to be seven times closer
than without the aid of a binocular. The number immediately
following the "x" is the diameter in millimeters
of the objective (front) lens. A 10x50 binocular, therefore,
has a 10 times magnification with a 50mm objective lens. |
| The exit pupil
refers to the size of the shaft of light transmitted to
the eye. The more light, the better the contrast. You
can actually see the exit pupil by holding the eyepiece
of the binocular approximately 12 inches from your eye.
It is the bright circle of light in the center of the
eyepiece. Exit pupil is expressed in millimeters and is
normally derived by dividing the power into the objective
lens diameter. A 7x35 binocular has an exit pupil of 5mm
(35 ÷ 7). |
| The field of
view is the width, measured in degrees or feet, of the
viewing area you would see at 1,000 yards. |
| Binoculars have
left and right side barrels linked to each other by an
axle. The two most frequently used prism systems are porro
and roof. Porro Prism binoculars are characterized by
the eyepieces being offset from the objective lenses.
Roof Prism binoculars feature lenses positioned in line
for a more compact design. |
|
also referred to definition,
is the ability of a binocular to distinguish fine detailand
retain clarity. |
| Optical glass
surfaces are coated by magnesium fluoride to reduce light
loss and glare due to reflection. Most binoculars are
fully multi-coated to further enhance viewing and reduce
eye strain. Some binoculars have a special image enhancing,
amber, high contrast coatings. |
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This describes a binocular's
ability to remain completely dry on the inside when exposed
to moisture or total submersion in water. Binoculars are
sealed with O-rings and are filled with 100% arid nitrogen,
which also resists all forms of moisture. |
| When light entering
the binoculars reflects off of interior surfaces, the
reflected light eventually exits inside the binoculars
in the form of stray light. This unfocused light typically
diminishes the image quality of the sight picture. |
| All binoculars
have the ability to be focused for infinity. So a primary
point of distinction between binocular models is the minimum
focus range. Birders tend to favor models with a short
focus range of about 15 feet, but 20 to 25 feet is usually
acceptable. |
| Using the
below formulas gives a basic evaluation of low light performance,
however, one must keep in mind that they are mathematical
formulas and do not take into effect some of the most
critical features in optics; glass quality, number of
lenses, precision of manufacturing and coatings. |
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| The spotting scope you
choose greatly affects how it will work for you under
certain conditions. For example, the person who only wants
to use his or her spotting scope at the rifle range can
often drive up to the bench and conveniently layout supplies
including a large objective porro prism spotting scope.
The target shooter could easily use a 80MM porro prism
scope on a full-length tripod and not worry about compact
design or lightweight since their automobile is a few
yards away. On the other hand, a person who is planning
an elk hunt in Montana's Bob Marshall Wilderness is probably
very concerned with weight and the ability to fit the
scope into a pack. Typically roof prism spotting scopes
offer the hunter or backpacker a more compact and lightweight
design to pack and carry long distances. While some porro
prism spotting scopes are quite compact, others can offer
larger fields of view and resolution, but they may not
be practical to pack into the woods. Other features for
the hunter to consider are rubber armoring to protect
the scope from blunt force. A waterproof spotting scope
offers piece of mind to the hunter working in rain and
snow.**This is not a comprehensive list of all the factors
to consider when choosing a spotting scope but it will
hopefully shed some light on some of the more critical
factors to consider. |
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The magnification feature of
a spotting scope allows the user to view an object much
closer than it would otherwise be using only the human
eye. The magnification power is a function of both the
scope's optical system and the eyepiece being used. Spotting
scopes such as Bushnell's Spacemaster® series and
Bausch & Lomb's Premier® HDR series offer the
user a choice of zoom eyepieces such as a 15-45x variable
eyepiece or high power fixed eyepieces such as 60x. Most
hunters prefer the versatility of a zoom (variable) eyepiece
for use at varying distances. Sometimes the higher magnification
offered in a zoom eyepiece can make the difference between
positively identifying a trophy animal and not knowing
for sure whether this is the Boone and Crockett animal
you've been tracking. |
| The objective
lens of a spotting scope serves to gather incoming light.
A 60mm objective lens will gather more light than a 50mm
lens. When more light is transmitted to your eye, you
will view a brighter and clearer image. Resolution (ability
to see detail) is also a function of the objective lens
diameter. |
| Eye relief is
the minimum distance between the spotting scope eyepiece
and your eye that still allows you to see the entire field
of view. Hunters and shooters who do not wear eyeglasses
can use most spotting scopes and eyepieces without any
trouble. People who wear eyeglasses are more concerned
with eye relief. When a person wears glasses while looking
through a standard spotting scope eyepiece their glasses
may touch the eyepiece. Bushnell offers two eyepiece enhancements
for those users wearing eyeglasses. Most Bushnell®
and Bausch & Lomb® spotting scope eyepieces offer
the ability to roll down the rubber eyecup thus increasing
the distance between your glasses and the eyepiece without
impairing the view. If even more eye relief is required
specially designed long eye relief zoom eyepieces are
available. The need for eye relief is an individual specific
need. Sometimes eyeglass wearers are more comfortable
looking through a spotting scope without their glasses
on. |
| Lens coatings
play an important role in getting the light gathered at
the objective end of the scope transmitted through the
ocular end to your eye. The lens coatings are partially
responsible for delivering a brighter and higher contrast
image. All Bausch and Lomb® spotting scopes offer
multi-coated lenses for superior images. Bushnell®
spotting scopes feature fully coated lenses. |
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| Telescopes are
described by a numerical representation such as 450x60mm.
The first number is the maximum magnification (an object
will appear 450 times closer than viewed with the naked
eye) and the second number is the diameter of the objective
lens (the closest to the object being viewed). |
| Unlike
conventional telescopes, this patented technology breakthrough
allows for left to right correct views of the stars--not
reversed. No more guessing which way to move the telescope.
This feature provides unparalleled ease of use for finding
and tracking objects with a convenient 90 degree viewing
angle and 1.25" eyepiece adapter. |
| Astro-nomical
and terrestrial viewers can zoom from 50x to 150x with
no refocusing of the telescope. This feature allows for
convenient magnification changes bringing the wonders
of the night sky up close and personal with a twist of
the power change ring. |
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Astronomical telescopes are designed
specifically for observing heavenly bodies: stars, planets,
moons, comets, etc. They are fitted with special features
to stabilize the telescope and track the movement of stars
and planets across the sky. They are very high powered,
with magnifications of 40x to 600x depending on the model. |
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On most astronomical telescopes
a lower powered finderscope with a wider field of view
lets the user quickly locate the object to be viewed by
the high magnification main telescope. |
| An auxiliary lens
that increases the power by a factor. For example a 2x
barlow would double the magnification of the telescope. |
|
In astronomical telescopes, interchangeable
eyepieces are used to vary the magnification of the telescope. |
| Lens used when
viewing land based objects that correct the normally upside
down and reversed image provided by an astronomical telescope. |
| This
patented feature allows for magnification and accessory
changes to occur through a simple twist of the turret
or accessory dial. Accessories are incorporated into the
telescope so there are no loose parts, and magnification
and accessory changes can be made instantaneously to suit
viewing conditions. |
| Allows
for quicker and easier set-up and storage as well as reduces
image shake caused by wind or ground tremors. |
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| Class 1 Laser-Classified
by the FDA. |
|
is simply the degree to which
the object is enlarged. With a 7x35 binocular, for example,
the object appears to be seven times closer than without
the aid of a binocular. The number immediately following
the "x" is the diameter in millimeters of the
objective (front) lens. A 10x50 binocular, therefore,
has a 10 times magnification with a 50mm objective lens. |
| Accurate within
+/- one yard. |
| Featured on
certain models, this highly advanced technology automatically
provides the distance to the closest object if two objects
are inadvertently ranged. For example: a golfer intends
to range to the flag, but the laser also picks up the
background behind the flag. Normally, the distance to
the larger object or more relective object would be displayed.
However, with pinseekder technology, the range finder
is able to provide the golfer the disatance to the flag
and not the background. |
| Many variables
contribute to ranging performance: weather, lighting,
target size, target reflectivity, target surface, the
angle at which the laser hits the targe and hand steadiness. |
Provides continous distance measurements as multiple targets
in the field of view are scanned.
Permits distance measurement in inclement weather such
as rain or snow.
Enables distance
measurement through foreground clutter.
Maximum distance to special reflectors
is enhanced. |
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Also called power and indicated
by the symbol "x". A 4x riflescope makes the
target appear four times closer than when seen with the
unaided eye. Choose high power for varmint shooting, medium
power for big game at moderate ranges, and low power for
precise, close range shooting at fast targets. |
| The distance behind
the eyeguard at which you can see a full-sight picture.
Bausch & Lomb and Bushnell riflescopes give you an
extra margin of comfort and safety with extended eye relief
and soft neoprene eyepiece guards. |
| The width of
the sight picture at 100 yards. A wider field of view
makes it easier to spot game and track moving targets. |
| Our
distortion-free optics give you a bright, super-sharp
sight picture. |
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A condition that occurs when
the image of the target is not focused precisely on the
reticle plane. Parallax is visible as an apparent movement
between the reticle and the target when the shooter moves
his head or, in extreme cases, an out-of-focus image.
Our centerfire riflescopes under 11 power are factory-set
parallax free at 100 yards: rimfire scopes at 50 yards.
Scopes of 11x or more have a special range focus to adjust
for parallax. |
| The diameter of
the shaft of light exiting the scope toward the eye. It
is used to rate the brightness of a riflescope's sight
picture. For example, a 4x scope with a 40mm objective
lens (the front lens) has an exit pupil of 10mm, a very
good rating. The larger the exit pupil, the easier it
is to keep the eye aligned with the sight picture, and
the better the scope will be in low light. |
| Our
manufacturers uses a high-durability aluminum alloy formed
into a one-piece tube. Each riflescope is rustproof, virtually
scratch-proof and a beautiful complement to your most
expensive rifles. |
| All
1" diameter Bausch & Lomb/Bushnell riflescopes
are not only nitrogen purged to remove any vestige of
internal moisture, they are O-ring sealed to prevent the
entry of external dust or moisture. Your riflescope remains
crystal clear in all types of weather. |
| A riflescope
feature that gives you a clearly visible aiming point.
Even when hard-to-see game blends into the background
or the light is poor. The fine-line crosshair center section
covers a minimum of the target. The heavier outside section
leads your eye directly to the center intersection. The
result is fast precision aiming. |
| Many rifle scopes
optical glass surfaces are coated by magnesium fluoride
to reduce light loss and glare due to reflection. All
Bausch & Lomb riflescopes are multi-coated to further
enhance viewing and reduce eye strain. All Trophy riflescopes
have a special image enhancing amber, high contrast coating. |
|
The revolutionary Bushnell HOLOsight
gun sight gives you instant target acquisition through
the holographic, heads-up targeting system from U.S. fighter
jets. |
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|
is simply the degree to which
the object is enlarged. With a 7x35 binocular, for example,
the object appears to be seven times closer than without
the aid of a binocular. The number immediately following
the "x" is the diameter in millimeters of the
objective (front) lens. A 10x50 binocular, therefore,
has a 10 times magnification with a 50mm objective lens.
|
| The field of
view is the width, measured in degrees or feet, of the
viewing area you would see at 1,000 yards. |
| An
electronic circuit that turns the power to the night vision
device down or off when it is exposed to bright light
(such as automobile headlights). This protects the image
intensifier and extends its life. The device will revocer
and resume normal operation in 1-2 minutes. |
| Used to match your
night vision scope or binocular to your specific eyesight. |
| The
active component in a night vision system that amplifies
light and presents a usable image. |
| Provides
a light source for the system to amplify, yielding enhanced
images in very low light conditions such as caves where
no ambient light is available for amplification. |
| Collects all available
light and focuses it on the image intensifier. It also
provides image magnification. |
| Positioned at
the back of the intensifier tube, the green phosphor screen
renders a visible night vision image. The human eye is
most sensitive to green contrasts. |
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Converts light (photon energy)
into electrons (electrical energy) which are then amplified
in the intensifier. The objective lens focuses available
light on the photoelectric surface of the photocathode,
which is excited and passes electrons within the tube. |
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A measure of the ability to render
and display a detailed image. Image intensifier resolution
remains constant and is expressed as the maximum number
of line pairs per millimeter (LP/MM) that can be discerened
when a black-and-white stripe pattern is focused on the
photocathode. |
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