 |
|
|
Simply stated, the night
vision binoculars is two telescopes mounted side by side with
prisms in the light path to turn the image right side up and increase
the length of the light path without significantly increasing the
physical length of the binocular.
Night
vision binoculars are tougher than ever, extremely lightweight,
with innovative design, durable construction and the benefit of advanced
optics technology for a lifetime of dependable performance! These
binoculars are among our most popular night
vision devices. The advanced technology used in night
binoculars enables clear and high-resolution imaging. Binoculars
can be used for various purposes such as bird watching, sports, hunting,
or simply while traveling. Night
vision binoculars are ideal for general security work, game keeping,
hunting or marine use.
Objective Lens of Night
Vision Binoculars
The diameter of the objective lenses
determines the light-gathering power and the ultimate resolving power
of binoculars.
The ratio of the focal lengths
of the objective and the ocular lenses gives the linear magnifying
power. The objective lens needs
to be large enough to give acceptable resolution in all circumstances,
but must be larger for low-light and night use. For general night
binocular use, a 50mm objective gives maximum brightness for 7 diameter
magnifications; objective diameter
must be increased for higher magnifications
at night.
Waterproof Binoculars
Waterproof Binoculars need to stand up in the harsh marine environment. Waterproof boating binoculars are absolutely necessary and night vision equipment for search and rescue or boating in the dark is essential.
Digital Camera Binoculars
Digital
camera binocular is a great combination of digital camera and
binocular. It is especially great for people who take long-distance
pictures. The digital
camera binoculars are great for bird watchers or wildlife enthusiasts.
Choosing Night
Vision Binoculars
For general-purpose use, 8x40 is a good combination. 7x50 is brighter for night use. Larger objective diameters have better light-gathering power, and can view fainter objects for astronomical use. If more compact binoculars are required, smaller objectives may be used at some loss of performance and increase in price.
7x50 or 10x50 binoculars are good general-purpose instruments which are excellent for astronomy, although even the most humble binocular will reveal a wealth of detail invisible to the naked eye. Larger binoculars will need to be mounted on a camera tripod and smaller ones give less bright images, although they can have the advantage of being extremely portable.
The 7x50 binocular has the best light-gathering, important for navigating in dim waters. The 7x50 is known as the 'mariner's glass'. It is large and heavy, and not suited to being carried around the neck for long periods, but when used on a boat it can be put down frequently on the chart table, or hung on a bulkhead.
The 10x50
binocular has higher magnification,
and a consequent reduction of light-gathering, but when the power
is important, such as for long range hunting or surveillance, this
is the glass of choice, especially if it can be rested on or supported
by something.
The 7x35 binocular has moderate magnification,
moderate light-gathering, medium size and weight, and does everything
fairly well. It is the all-purpose binocular.
The 8x40 binocular is the bird watching binocular. The slightly higher
magnification, good light-gathering
and medium size makes it the perfect choice for carrying in the field
all day looking for that rare bird.
What do the numbers mean?
Binoculars are labeled with numbers like 7x50 or 8x40 or 10x50. The
first number is the magnification,
or the number of times the binocular magnifies what it is looking
at. The x means 'times' or 'multiplication' just as in arithmetic.
The second number is the diameter of the objective
lenses in millimeters. The objective
lenses are the large lenses on the front of the binocular, the
end closest to the subject.
What do these numbers tell us?
The first number tells us how much nearer objects will look when viewed through the binocular. An object (like a bird, ship, or race horse, for example) that is 500 feet away will appear 1/7 of that distance (71 feet) in a 7x glass, 1/8 that distance (62 feet) in a 8x glass, and 1/10 the distance (50 feet) in a 10x binocular.
The second number tells us first, how big the binocular is. A glass with 50mm (millimeter) or larger objective lenses will be fairly large and heavy, whereas a binocular with 21mm lenses will be small and compact.
These two numbers together tell us the light gathering power of the
binocular.
Divide the objective size (second number) by the magnification
(first number) and you arrive at the Exit
Pupil. This Exit Pupil is the
small circle of light you see in the eyepiece
when you hold the binocular at arms length toward a light source such
as the sky or a light colored wall. The larger this exit
pupil, the more light is getting through to your eyes, which is
a desirable characteristic, especially in dim light.
|
|
|
