Answers
To Your Frequently Asked Questions About Night Vision.
Q.
What is Night Vision used for?
A.
Recreational uses consist of camping, hiking, fishing,
boating, and nature viewing. Other uses include
surveillance, search and rescue, and property management.
Q.
What is the difference between night vision generations?
A. The
key difference between the night vision generations is the
intensifier technology. Gen. I devices use an intensifier
tube that amplifies ambient light by accelerating electrons
and striking a phosphor surface just like a Television.
Generation II devices add a micro-channel plate that
multiplies the number of electrons before they impinge on
the phosphor screen, thus increasing gain; Generation III
devices further add a Gallium Arsenide photocathode which
creates significantly more photoelectrons than Gen. II
devices. Generation II and III devices offer greater light
amplification but a price beyond the reach of most buyers.
Generation I devices are high quality and provide light
amplification adequate for most recreational activities and
for many professional uses.
Bushnell
has introduced an Advanced Night Vision device
that produces images comparable to Generation 2 devices. The
Advanced Night Vision device does not contain a Micro
Channel plate, but uses fiber optic bundles to eliminate
distortion thus providing excellent resolution and a flat
field of view. The result is superior image quality
comparable to Generation 2 devices at half the cost.
Q.
How does Night Vision work?
A.
Bushnell Night Vision products collect and amplify existing
light through the objective lens which is then focused on
the image intensifier. Inside the intensifier, a
photocathode is "excited" by the light and
converts the photon energy in to electrons. These electrons
accelerate across an electrostatic field inside the
intensifier and strike a phosphor screen (like a green
monochrome TV screen) which emits an image that you can see.
It is the acceleration of electrons, which provides gain and
enhances the image.
Q.
Aren't all Night Vision products the same?
A. No.
Only Bushnell Night Vision comes from a proven Leader and
Innovator in the Sports Optics Industry.
Q.
What is the effective range of night vision?
A. It
varies anywhere from 1-1800 feet. The maximum viewing
distance depends on the conditions of use and upon model
chosen. Overcast conditions, fog, rain; etc. may reduce the
effective distance of a night vision. An Infrared
Illuminator will increase viewing range, especially in
enclosed areas like a warehouse, cave, or thick brush.
Q.
Why isn't there more magnification in a night vision device?
A. The
more you magnify the more light you lose.
Q.
Why do you focus both the front (Objective lens) and
Eye-piece (Ocular)?
A. The
short answer is that you don't see through the night vision
device, rather you see the phosphor screen on the back of
the tube. The objective lens focuses the image on to the
front of the intensifier tube. That image is then converted
in to electron energy. It paints that picture on the back of
the tube. You need to have a sharp image to start with. Then
your eye needs to be focused onto the back of the tube where
the image resides. Every eye is different and therefore the
ocular focus is very important. Focus the ocular first and
then move to the objective lens. You may have to adjust each
lens several times before getting a sharp image.
Q.
How do I use a Bushnell Night Vision device in extremely low
light, or no-light conditions?
A. All
night vision devices need some available light to work. It
is possible to see a bright image in low light or no light
conditions with the use of an Infrared Illuminator. An
Infrared Illuminator is standard on all Bushnell Night
vision devices.
Q.
Since a night vision device is sensitive to Infrared (IR)
light, can it detect heat?
A.
Night vision devices operate as a light amplifier for light
in the "near visible" light range. Generally, this
is in the 750-850 nanometer range. It can not detect heat,
which is at a much lower end of the light spectrum and
requires thermal imaging technology.
Q.
What type of light source can be harmful to a night vision
device?
A.
Night Vision devices are designed for use in the dark. It
may be harmful and can damage the device if you use it
during the daytime or in other very bright situations. Keep
in mind that strong direct light, such as projectors, car
headlamps, strong flashlights, and so on, may be harmful to
your night vision unit if you direct your device at the
source of these intense lights. With this said, Bushnell
Night Vision devices have electronic protection against such
damage. Most of these are simple turn off overload circuits,
but some have more sophisticated and separate light sensing
mechanisms.
Q.
What characteristics might I expect from my Night Vision
device?
A. All
Bushnell Night Vision Monocular scopes are activated in a
way that can not be left on when not in use. The power
button is designed to give power only while being depressed.
The
binocular devices do have on/off switches that require the
user to remember to turn off the unit. Some level of
"buzzing" sound is quite normal and is intended to
be useful in remembering to turn off these units when done
using them.
The
image of a night vision device will not be as sharp as that
of a daylight binocular. This is due largely to the image
being generated on a phosphor screen.
Black
spots may be visible in the image. This comes as a natural
process of manufacturing the intensifier tubes.
Q.
What's inside a night vision scope?
A. A
night vision scope is made up of a set of optics (glass), a
simple power supply (batteries, wire, transformer,
regulators and capacitors) and an image intensifier (a glass
vacuum tube with a light sensitive coating at one end and a
phosphor screen at the other).
Q.
Are Bushnell Night Vision devices safe?
A.
Yes. All of Bushnell's Night Vision products include
shield-encased image intensifiers to block x-rays. All of
Bushnell's infrared illuminators utilize harmless filtered
incandescent bulbs or light emitting diodes (LED's) instead
of lasers.
Q.
How should I care for my Night Vision device?
A. The
number one damage factor is using the device in bright
light. While all Bushnell Night Vision devices have a
cut-off circuit when over exposed, exposure will shorten the
life span of a night vision device.
- Exposure
to rain, fog, or even extremely high humidity may damage
night vision devices. Built for use at night, they can
withstand short exposure to dampness or high humidity
conditions.
- Night
Vision devices have delicate vacuum intensifier tubes
that are sensitive to impact and should be handled
carefully.
- Clean
lenses the same way you would your camera. The lenses
are optically coated and may be scratch if abrasive
material is used or if dirt is rubbed into the glass.
Usually there is no need to remove the lenses and clean
inside.
- Storage
for long periods is best in a cool dry place with the
batteries removed.
Q.
What is the warranty for Night Vision devices?
A.
Bushnell Night Vision products are unquestionably warranted
to be free of defects in material and workmanship for two
years after the date of purchase. In the event of a defect
under this warranty, we will at our option, repair or
replace the product.
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