Determining
the difference between night vision devices is not an easy task.
What is Night Vision and how does it work?
Night vision allows the user to see objects and surroundings even under the
darkest conditions. Simply put the unit collects ambient light, or uses light
from an infrared illuminator, the intensifier tube electronically amplifies
this light and projects a green image on the screen for the user to see.
1. How
does night vision work?
The objective lens collects light that you cannot see with your naked eye and
focuses it on the image intensifier.
The intensifier amplifies the light many hundred or thousand times.
2 a. What is the difference between Generation 1, 2, and 3 night vision
devices?
Night Vision devices of all generations are evaluated based on a universal
rating system.
The three main criteria are System Light Gain, System Resolution, and
Photosensitivity.
- System light gain evaluates how many times a night vision unit is amplifying
the available light.
- System Resolution reveals information regarding the sharpness and clarity of
the amplified image.
- Photosensitivity determines the minimum light level and type of light needed
in order to function properly.
| Image Intensifier Light Amp. |
300-900 |
20,000-30,000 |
20,000-30,000 |
| System Light Amplification |
<1,000 |
<6,000 |
<6,0000 |
| Resolution in the center, ln/mm |
25-30 |
30-68 |
45-68 |
| Resolution on the edge ln/mm |
15-20 |
30-68 |
<45-68 |
|
2 b. How
to tell Gen. 2 (or 3) from Gen. 1 device: Quick Rule of thumb:
Turn off the unit. If it shuts off immediately - it is a Gen. 2 unit. If the image
remains for some time - it's a Gen. 1 unit.
2 c. Other companies claim to have products with 10,000, 20,000, 40,000 light
amplification etc. Why?
The best US made 3rd. gen. devices that cost $10,000 USD have a 3,000 system
light amplification. Anybody claiming higher is not telling the truth and simply
misleading the customers, who have no practical way to verify those figures.
3. Why are domestic products so much more expensive ?
- Our products are made in Russia, where material and labor is much cheaper
than in the USA
- The only way to compare is Apples for apples- Gen. 2 US. made versus Gen. 2
Russian made. US. is more expensive.
4. Can night Vision equipment be used in daytime?
NEVER expose the opened objective lens of an active unit in daylight. During
the day objective lenses must be covered by caps.
There is a tiny hole in the cap to provide enough light for day time operation.
The unit may be turned on during daytime but the lenses must be covered by
caps.
NEVER aim an active unit at intense light sources (i.e. lights, headlamps,
campfires, the moon, etc.). This may damage the image intensifier.
5. Why do I see some black or white spots in the viewer?
These are the cosmetic blemishes in the image intensifier which do not affect
the performance or reliability of a night vision device and some number of
varying sizes are inherent in the manufacturing processes.
They can also be dirt or debris between the lenses which should be removed by
careful cleaning if the system is designed with interchangeable optics.
6. Why do all night vision equipment have a small magnification?
Consider the distance you will need and the overall area you are observing or
searching. For most surveillance or search applications, the higher the
magnification or narrower the field of view, the greater the number of times
you need to scan an area to avoid missing important objects or events. Usually
a 1:1 lens with a 40- field of view provides optimal performance. For long
range observation or weapon sight applications, the amount of magnification
needed will vary; however, be sure to consider the other performance
characteristics of the device; as the magnification increases, field of view
decreases and the F number increases, all reducing the amount of light
captured. Consequently, you will need an image tube with excellent performance
at very low-light levels and /or high-performance lenses. Another factor
involves the versatility of a device if it is used in situations that may
require different magnification. How easily and quickly can the magnification
be changed? Is it necessary to open the system to install the optics? In some
cases, this may be inescapable, and the susceptibility of internal components
to damage should be considered.
7. Is Night Vision legal?
Yes, for all devices. Possession of a night vision device conforms with Federal
Firearms Regulations, as of February, 1993. However, use of a weapon sight for
hunting may be limited or illegal in your state. Check with your local authorities.
8. Will it make me blind if I look at a bright object ?
This only happens in the movies. In real life, all of our devices have
automatic brightness control. The unit will adjust the output according to the
incoming light, and will shut itself off if necessary.
9. I have heard it is unsafe to look into the Infra Red illuminator. Is it ?
There is some base to this rumor. Many military night vision devices utilize
Lasers in their Illuminators, and some of them might not be safe.
All of our products use low power infra red diodes, identical to the ones used
in T.V. remote controls, which are absolutely safe.
What To do and Not to do:
NEVER
take the unit apart. This device contains high voltage, which may be hazardous
to your health!
NEVER expose the opened objective lenses of a unit to
daylight. (Note: 1st generation units will still remain active for a few
minutes after switching the unit off). During the day, caps must cover
objective lenses. There is a tiny hole in the lens caps to provide enough light
for daytime operation. You can turn the unit on in the daytime, but the caps
must be on the lenses.
NEVER aim an active unit at intense light sources (i.e. lights, headlamp,
campfires, the moon, etc.) It will not make you blind like in the movies, but
it will harm the unit.- NEVER reverse the polarity of a battery.
NEVER connect the unit to external power sources.
ALWAYS keep the objective lenses covered when not in use.
ALWAYS store in a warm dry place when not in use.
ALWAYS remove battery when not in use for a long period of time.
Glossary
of terms:
Image
Intensifier Tubes: Collects and amplifies light, which is then displayed so
the image can be seen by the viewer.
Binoculars
Vs. Monoculars: A night vision monocular is for use with one eye and contains one
image intensifier tube. A night vision binocular is for use with both eyes and
contains two image intensifier tubes.
Generations: The qualities of
different night vision systems are graded by generations. Simply put, Gen 1 was
developed first, but is still in production because it is still sufficient for
the average consumer and the cost is affordable. Gen 2 came next considerably
increasing the quality of the image intensifier tube. Gen 3 followed with an
even better tube. Following this, some companies decided to develop the Gen 2
technology and that leaves what is now referred to as Gen 2+, which is
consistently compared on par with Gen 3.
Infrared
Illuminator: Allows for optimal use even in no light conditions, completely
eye safe, it gives off a light your eye cannot see but that is received by the
night vision device.
Resolution: measured in line
pairs per millimeter (lp/mm) it is the clarity or quality of the image seen on
the screen. The higher the number, the better the image quality. However, buyer
beware, these numbers are often inflated by some companies because it is
impossible for the average consumer to test this measurement
Magnification in Night Vision: Higher is not always
better, and this is one of the cases. The higher the magnification the lower
the brightness. Therefore with night vision you want a fairly low
magnification, after all you are trying to see in the dark not see something
far away.
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