Night Vision Scopes & Goggles
Lensing
Read below to learn the difference between scopes  (monoculars) and goggles (binoculars).
| Scopes |
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Scopes can either be of the handheld or mounted variety. Typically, mounted scopes are best on a weapon. Since scopes are monocular (one eye piece for viewing with one eye) they are not worn on your head for long periods of time, but used for temporarily viewing an object. This allows the user to quickly and efficiently switch between the scope and normal viewing, which is best when there is still some ambient light to help you see without the device.
You may also like to search for: spotting scopes and rifle scopes. |
| Goggles |
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Goggles are binocular (two eye pieces) and they use either a single or dual set of lenses. The single-lens goggles (pictured) are different from scopes in that they are designed for viewing by both eyes. All goggles are either handheld or worn on the head. The hands-free head versions allow you to move around freely without having to carry the goggles. This type is best used if you plan to wear the goggles for extended periods of time -- if you find yourself in pitch or near-pitch darkness, for example. Those who expect to find themselves in such situations often should look into infrared goggles. |
Generation Gaps
There are five "generations" of NVDs: zero, first, second, third, and fourth. For a more detailed explanation of the generations available, see this FAQ.
- Zero generation models, originally designed for military use, are active infrared devices.
- First generation NVDs have the lowest quality light intensifier tube (meaning they display the lowest resolution images). They are perfect for wildlife hunting, fishing, boating, and general home security. They can produce a slight noise while running and are prone to geometric distortion, which means that images can blur around the edges.
- Second generation models are geared towards serious enthusiasts, professionals, and law enforcement workers, since they cost $500 to $1000 more than a first generation NVD. The additional cost stems from their special MCPs (Micro Channel Plates) that enlarge and sharpen the images.
- Third generation NVDs cost more than $3000 and are the most high tech. They use a special chemical inside the tube called gallium arsenide that enhances the images even more by reducing background noise and increasing the signal to noise ratio. This is what military forces use.
- Fourth generation is the highest quality for viewing in any light conditions. Known as filmless gated NVDs, these increase the signal to noise ratio even more, reducing "snow" by removing the needless ion barrier film used in the third generation's image intensifier. These can even be used in daylight (as binoculars, one assumes?).
What to Expect
Here are some of the things that will affect how well and how far you can see with an NVD: - Ambient Light: Light from the moon, stars, and cities will inevitably make it easier to see at night. If you plan to be out under the stars or moon, a first or second generation is adequate. In cloudy conditions and under sparse stars a third generation is best, but unless you're doing special ops or some well-paying nighttime scheme, there's no reason to invest so much money.
- Object Size: Generally, a person is easier to see than a rabbit. What do you plan on looking at?
- Detection Range: Do you want to know if there is something out there in the dark or do you want to know what brand of clothes someone is wearing? Seeing a blurred object is one thing, seeing details is another.
What to Look For- Photosensitivity: The higher a device's photocathode sensitivity, the easier it can pick up images in low light. It's measured in microamps of current per lumen of light (uA/lm). A first generation model will have a photosensitivity of approximately 180-200mA/lm. A second generation goes up to 240+mA/lm. And so on.
- Resolution: Look for high resolution line pairs. Often you will see numbers such as 40IP/mm in first generation NVDs, but you will se 50-64 or more in third generation NVDs. This is a very good measure of how good the device is in terms of image clarity and sharpness.
- Magnification: This is measured in Xs, from 2.4x to 10x or more. The higher the magnification number, the bigger the images will be when seen through the NVD. While it may seem better to go with a higher magnification, that is not necessarily the case. Your best bet is to find something with high speed photosensitivity and a low magnification number (less than 5x).
- Water Resistance: If you plan to be in the elements with your NVD, you will want it to repel water.
- Long Battery Life: Continuous use of an NVD will drain the battery quickly, but some models have twice as much life as the others. Expect anywhere from 5 to 20 hours of continuous life. Always expect the life to be closer to the lower number given in the range.
- Weight & Size: Weight adds up quick over time so you want something very lightweight. Most models weigh in at around a pound or less. However, there are some scopes that can weight close to 3 lbs. As far as size, this varies depending on the model and the generation. Often higher generation models will be bigger. Choose accordingly, and remember that before choosing you should know whether you want something that can fit in your pocket, wear around you neck, or throw into your pack.
- Warranty: Models with higher warranties usually mean better quality.
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