Never observes the Sun through your binoculars, monocular, telescope,
Spotting scope etc.! Observing the Sun, even for the shortest fraction
of a second, will cause instant and irreversible eye damage. When
using your BCI optical products during the daytime, do not point
it even close to the Sun.
BCI Binoculars are designed and
manufactured by BCI whom strive in cutting edge design and user-friendly
equipment that is comfortable as well as appealing to the eye. "The Closer You Look, The Better It Gets!"
The basic mechanism of binoculars consists of four parts - object
lenses, ocular lenses (eyepieces), prisms and focusing system. Object
Lenses are the larger lenses at the front taking light into binoculars.
The bigger they are, the more light the binoculars gather, and usually
the finer the image's resolution is. It is therefore necessary to
use binoculars with large object lenses in low light conditions.
Ocular Lenses or eyepieces are the smaller lenses at rear delivering
the final images to user's eyes. The bigger they are, the less eyestrain
is put upon the user. Prisms are pieces of triangular glass inside
binocular barrels correcting the image, which would otherwise be
inverted and reserved without them. Focusing System lets the user
adjust focal length of binoculars so that images appear sharply
Magnification (how close it makes things appear), Resolution (sharpness
and clarity) and Light Transmission (brightness) are important
for binoculars performance. Ignoring a single key point will
be at the expense of the others erodes a binoculars optical quality.
Powerful magnification is useless if the image is dim or fuzzy.
Larger binoculars may provide greater magnification, but it requires
larger objective lenses to enhance resolution and brightness. When
considering brightness, there are limits to the amount of light
the eye can receive. During the day, it needs to eliminate some
light, while at night it needs to transmit more. Therefore, some
larger objective binoculars are ideal for night while smaller objective
binoculars are better for day. Most importantly, know the intended
use and try before you buy.
Magnification or Power:
Binoculars are referred to by a combination of numbers, e.g., 10x
50mm. The first number refers to the power of the binocular. It
indicates the size to which an object is enlarged. For example,
an object 1,000 meters away when viewed with 10x binoculars appears
only 100 meters away, or 10 times (X) larger than with the naked
eye. Higher magnification does not necessarily mean better. If the
magnification is too high, the object does not appear clearly due
to binoculars shake (caused by a slight trembling of the hands.)
Generally, binoculars shake is not a problem with magnifications
of up to 8x. You can also use binoculars with a 12x magnification
without binoculars shake once you become familiar with them. Generally, the higher the magnification, the
narrower the real field of view, and the lower the brightness. Take
7x50 and10x50 binoculars (both featuring objective lenses with the
same effective diameter) for example. Although the object appears
bigger when looked at through the 10x50 binoculars than through
the 7x50 model, the lower magnification model offers a much brighter
image and a wider real field of view. It is therefore important
to choose binoculars with an appropriate magnification.
Resolution: Resolution is a measurement of the binoculars
ability to distinguish fine detail. Better resolution also provides
more intense color. Resolution varies directly with the size of
the objective lens. All else being equal, a larger objective lens
will always deliver more detail than a smaller one regardless of
the magnification. Actual resolution hinges on a variety of factors:
the quality of the optical components, light transmission through
the binoculars, existing atmospheric conditions, optical and mechanical
alignment (collimation) and visual acuity of the individual.
Light Transmission: The size of the objective lenses determines
the amount of light that reaches the eye. With larger the objective
lens, you can have better brightness and sharpness of the image
seen through the binoculars.
are two prism styles for binoculars - Porro Prism and Roof Prism.
prism system gives the user better perception of depth and stereoscopy
by offsetting the prisms making the binoculars size bigger than
comparable roof prism model. It has a distinctive shape characterized by the use of a combination
of two right-angle Porro prisms and, externally, by the offset positioning
of the eyepieces from the objective lenses.
system offers more compact bodies with the prisms positioned in
line with object lenses and eyepieces. Prisms are positioned one over the other,
lining up the objective lenses and eyepiece centers. The result
is a more compact design, allowing pocketsize binoculars to have
full-size power capabilities.
structure decides the exterior shape of binoculars. Typically, roof
prism binoculars are slim and straight while porro prism binoculars
are bigger in horizontal direction needing more space for prisms.
products have a variety of appearances to meet individual user's
Non-prism binoculars---Galilean binoculars Generally known as opera glasses. "Galilean
binoculars" were named after their inverter, Galileo GALILEI
(1564~1642), the Italian astronomer. These binoculars consist of convex
lenses for the objectives and concave lenses for the eyepieces. They
form upright images. With a simplified prism-less optical system,
Galilean binoculars feature neither high magnification nor a wide
field of view (e.g. 430BR 4x30mm binoculars).
system acts as the co-coordinator between the user and the binoculars.
Apart from fixed focus models, all other BCI binoculars have a Central
Focusing mechanism. The focusing wheel at the center of binoculars
can be turned to focus on the targeted object.
It is quite
possible an average person has different eyesight between the two
eyes. A right eye Diaper Adjusting System is provided to overcome
the problem. The folding action of the two halves of the binocular
adjusts to compensate for individual differences in the spacing
between the user's eyes. This distance is known as the interpupillary
distance, or IPD. Adjustment of your personal IPD is an important
step in the proper use of your binoculars:
1. Hold the binocular up to
your face in the normal viewing position, using both hands to hold
each barrel firmly.
offer a wide range of pupil distances so anyone can use Nikon binoculars
in comfort. While you look at a distant object, carefully move the
binoculars barrels downward or upward so that both fields are correctly
aligned, forming a perfect circle.
distance is not adjusted. (The central part might be invisible
or an eclipse might appear at the corners.)
distance is properly adjusted.
uses two types of diopter adjust systems.
eyepiece diopter adjusting in which the user turns the right eyepiece ring.
1. Set the
Diopter Knob (see diagram) at zero.
through the binoculars at an object that is at least 100 feet (30
the lens cover or your hand, cover the right Objective Lens so that
you will be looking through your left eye only.
the Center Focus Knob until the object you are viewing with your
left eye is sharp and clear. At this point the object is in focus.
the lens cover (or hand) from the right Objective Lens and cover
the left Objective Lens so that you will be looking through your
right eye only.
looking at the object, rotate the Diopter Knob until the object
you see through your right eye is sharp and clear. At this point
the object is in focus.
7. Now with
a turn of the Center Focus Knob, only, both near and far objects
can be brought into focus.
Focus with your left eye.
Adjust diopter with right eye.
When the diopter is adjusted, turn the central focus knob to focus on the object.
Diopter Locking (such as UCF items)
in which the user presses and releases the diopter button behind
the focusing wheel to twist adjust and pushes down the button to
lock the setting. With your diopter setting adjusted and locked,
your vision requirements are stored without adjusting each tine
you use the same binoculars.
importance of immediately catching moving objects with binoculars
in some circumstances, BCI has developed a number of fixed focus
models (compact, full size, water-proof) with pre-fixed focusing.
If you are going to watch races for fast-moving spectator sports,
or going sailing, these binoculars are perfect to use provided a
recommended minimum distance of 15~50 meters (different models has
different pre-fixed optical system) exists between you and the object
with individual focusing (e.g. you can adjust the diopter of both
eyepieces independently. Focusing and diopter adjustments are performed
simultaneously, but a change of object requires both rings.
coating plays an important role in improving image brightness. When
light passes through a lens, some light is reflected by the front
and rear surfaces of the lens. This light causes flare or ghosting,
reducing image sharpness and contrast. Vacuum-vaporized coating
puts a thin, transparent film on the lens surface minimizing these
adverse effects. Some BCI binoculars incorporate multi layer
coated lenses covering a wide range of light wavelengths, ensuring
brilliant, clean images even in dim light. Transmission factors
for uncoated lens surfaces, lenses with a single coating, and lenses
with multi layer coating are shown in the following table. Since
several lenses and prisms are used in binoculars, differences in
transmission factors become greater as the number of lenses increases.
(See the table below.)
single lens surface
lens and prism surface
(0.96)10 = 0.66 (66%)
- layer coating
(0.985)10 = 0.86 (86%)
(0.995)10 = 0.95 (95%)
Optical coatings reduce reflection
both internally and externally and thereby increase the amount of
light that reaches the eye improving brightness and contrast. All
BCI products employ high-tech coated Optics helping to increase
the amount of useful light coming into the binoculars, thus providing
an image that is brighter, sharper and clearer. Generally speaking
the more layers optics is coated the better the image quality is.
Having every single surface of lenses and prisms coated with light-enhancing
chemicals, BCI binoculars promise high light transmission efficiency.
most BCI optics can be treated with a layer of Ruby Coating on top
of the normal coatings. It protects user's eye from UV emission
and further improves the light transmission. It offers brilliant,
crisp daylight viewing and is especially suited for use over water,
snow an in other bright conditions.
Coated: Lens and prism surfaces are coated to improve light transmission
Fully Coated: All air-to-glass surfaces are coated.
Multi-Coated: One or more surfaces of prisms or lenses have
been coated with multiple films.
Fully Multi-Coated: All air-to glass surfaces have multiple
Ruby Coated: This coating consists of 14 layers of multi-coating
on the objective lenses and is characterized by ruby-red coloring
on the objectives. It provides excellent bright daylight and glare
conditions viewing because it filters out red light.
Hydrophobic (water-repellent) Coated: High-tech military
coating now for sports optics. With it condensation from rain,
fog or snow forms in more smaller droplets than on other coatings.
Such smaller droplets scatter less light, which results in increased
light transmission and a clearer vivid image.
view is the angle of the visible field measured from the central
point of the objective lenses. The bigger the value, the wider the
field of view, and the easier it is to locate the object. The wider
the field of view the better for watching moving or large-scale
of view is the width in meters or feet of the area you see 1000
meters (1094 yards) away. You may see the expression in degrees
too, thus the term being Angle of View. One degree equals about
17.5 meters (57.4 feet) of width at 1000 meters. High power
binoculars usually have a narrower view angle compared to lower
power binoculars. More efforts are needed to keep the image stable
if you hold the binocular with hand. Let BCI binocular holder &
tripod do the job for you.
to the Japanese Industrial Standard (JIS)
binoculars with wider view angle can give user a more comprehensive
visual perception. BCI has many Wide Angle binoculars. They are
particularly needed for sporting events and camping. In wide angle
binoculars, the prism are specially ground to have their refraction
Zoom Binoculars are designed to have an extent of magnifications.
For example, BCI CT126050 binocular have a low of 12 magnifications
and a high of 60. By moving the zooming lever at the outside of
the right barrel, any magnification within the extent can be gained.
This feature presents you with a scope of viewing effects.
lenses and wet prisms are no fun to binocular users. BCI Water Proof
series is the solution to them. Equipped with thoroughly concealed
bodies and nitrogen filled barrels with O-rings, these binoculars
are totally waterproof. Fog formed inside the lenses as the result
of sudden temperature change will dissipate sizes within one minute.
With many models in different sizes to select, they are highly praised
by people like fishing lovers, camping fans and snow skiers.
relief is the distance between the eyepiece and the eye point. When
you place your eye correctly at the eye point, you can see the whole
field of view without any shading. If the eye relief is too
short, you cannot place your eye at the eye point and the field
of view is partially shaded off. High eye point binoculars
with longer eye relief (15 mm or longer) are recommended for eyeglass
wearing glasses or sunglass are likely to suffer from eyestrain.
BCI Long Eye Relief Binoculars can be very beneficial. Achieved
by using bigger than normal eyepieces (e .g. CT series), this feature
allows the user to place the binoculars at a longer distance from
eye without affecting field of view, thus relieving the efforts
of eye muscles to focus on the image. Image stability of these BCI
binoculars is also improved enabling the user to look for longer
Eye relief is the distance between
the eyepiece lenses and the eye point at the time of focusing.
BCI long eye relief models ensure comfortable, appropriate viewing,
and make it possible for wearers of glasses to see clearly up to
from eye relief point b)
View out of eye relief point
proper focus setting, first pull the lever to maximum power position
and pick an object at far distance. Then rotate the central focusing
wheel to set focus for left barrel. Next, adjust the right eye diopter
until the image is focused for both eyes. Focus setting is now completed.
View angle narrows as the magnification increases. The bigger the
view angle, the easier find the position of an object. Therefore
it is recommend that you set the power at lowest level and locate
the object before zooming it in for detailed viewing.
BCI series Binoculars (e.g. 842ZX) are armed with the best available
BaK 4 Prisms. These prisms are made from high-density optical glass,
which eliminates internal light scattering, bringing you the image
of highest possible fidelity. Hold the binocular about 30cm away
and look through the eyepieces; you will see a perfect round if
the prism is BaK 4. In the case of BaK7, the image is square with
grayish edges (cause
loss of light, resulting in reduced image brightness).
exit pupil is the bright circle as seen on the surface of the eyepiece
from about 30 cm (1 feet) away when you point the objective lenses
toward a bright light.
Simply put, the bigger the exit pupil, the brighter the image. The
diameter of exit pupil is calculated using the following equation:
brightness depends to some extent on the diameter of the human pupil.
If you use binoculars with an exit pupil diameter nearly the same
size as your own pupil, the light entering the binoculars will reach
the eye most efficiently.
As a human pupil normally opens 2 to 3 mm in daylight, binoculars
with an exit pupil of around 3 mm will provide sufficient brightness.
However, the human pupil extends to about 7 mm in the dark, so binoculars
with an exit pupil diameter of around 3 mm provide insufficient
light in the dark, resulting in a dark image. Therefore, binoculars with large
object lens such as 7 X 50 (exit pupil 50/7 = 7.1 mm) will be advantageous
for birding at dawn or dusk.
aperture is an opening of the objective lens through which light
can pass without eclipse. Generally, the inner diameter of an objective
lens is specified as the effective aperture. Remember, the larger
the effective aperture, the greater the resolving power, and the
brighter the image. But increasing the effective aperture of an
objective lens means bigger, heavier binoculars. An effective aperture
of Ø 50 mm is generally the limit for manual operation.
alignment of the optical elements of a pair of binoculars to the
mechanical axis is called Collimation. It is one of the most important
aspects to inspect when you buy. Binoculars with good collimation
should not form double image. BCI binoculars are carefully adjusted
and tested for their collimation by specially trained quality controllers.
We strongly recommend that you choose binoculars with metal prism
holders since any smallest deformation or dislocation of holders
will pervert your binoculars' collimation. Holders made from soft
material such as plastic can be out of shaped in as little as few
weeks, creating collimation defect and causing eyestrain and headache.
binoculars are itemized with two numbers followed by a string of
letters. The first number represents the Magnifications Power. The
second number indicates the diameter of the object lenses measured
in millimeters. For example 821BR means they are 8 power binoculars
bringing the object 8 times closer to naked eye. The size of the
object lenses is 21mm. The letters at the end are associated with
the model design of the product. Backed by the strength in expertise
and technology of its manufacturing base, BCI produces a wide range
of models, giving you the flexibility in choosing binoculars to
serve your needs.
following these guidelines your BCI binoculars will provide perfect
optical performance for many years:
1. Keep binoculars lenses clean and free of moisture
2. When not in use, do not expose your binoculars
to direct sunlight for long periods of time (e.g., on the dashboard
of your car).
3. Store your binoculars in a cool, dry
place. Always store your binoculars in its carrying case, with the
rubber eyecups in the "up" position.
4. Binoculars are complicated precision
optical instruments: handle them with care. Do not drop, shake,
bump or rattle your binoculars. Binoculars optics can become misaligned
(out of collimation) as a result of rough treatment, rendering the
binoculars virtually unusable. Collimation problems caused by rough
treatment require repair by a trained technician. Such collimation
adjustments are not covered by the Warranty.
To clean your binoculars, follow these steps:
1. Before attempting to clean
any of the lenses, carefully remove, with a soft lens brush or "canned
air," all grit, sand, dirt, dust, or other substances which
may scratch the surfaces of the lenses. Then use soft lens cleaning
tissues, a lint-free cotton cloth, or a clean cotton swab.
2. For materials that remain on the lenses, use a lens cleaning
solution (e.g., a commercial optical lens cleaner, or household
window cleaner) to remove grease, etc. CAUTION:
Do not apply liquid directly onto a lens, which may result in the
liquid seeping into the barrel of the binoculars.
Apply the solution onto a cloth or swab. Then apply light pressure
to remove the foreign substance with soft circular motions of the
cloth or swab. Note: Excessive pressure used when cleaning dirty
lenses (e.g., rubbing gritty dirt into the lens surfaces) may damage
coatings. Use a light touch.
3. Once foreign substances have been removed
from the lens surfaces, breathe onto the lenses to apply vapor.
Before the moisture evaporates, gently polish the lens surfaces
with a clean cotton cloth or lens cleaning cloth.
4. For more thorough cleaning: remove dirt
or liquid from under the binoculars eyecup flange (next to the eyepiece
lens surface) by removing the eyecup, gently lifting it up and carefully
cleaning the entire lens surface as described above.