Night Vision News
The Whole Truth, plus warnings of fictions and myths...
Night Vision will not turn "night into day". What it will do is make the otherwise invisible visible. When to the naked eye the night is pitch-black, with a night vision scope you will be able to see.
The Generation Game
One of the historic difficulties in buying night vision has been the false performance claims, particularly a problem with American dealers.
Within a generation 1 unit a photocathode plate converts photons into electrons. The electrons are accelerated through a megaphone shaped device called an anode cone onto a phosphor screen running at a higher voltage. It is this use of an anode cone which causes the focus to be perfect only in the centre of the image, and the effect is common to all first generation night vision devices. Where you don't see this loss of focus it will be because the field of view has been deliberately restricted to hide it. The expected light amplification is between 150 and a theoretical 400.
Generation 2 and 2+ products use a microchannel plate between the photocathode and the phosphor screen. This plate is a bundle of fibre optic cables, (up to 6.3 million of them depending on the manufacturer). As the electrons pass down the fibre optic tubes they bounce off the sides, multiplying with each strike, so that light gain is increased to between 20,000 and 30,000. Geometric distortion is very much reduced and the focus is 100% across the whole image, with very much better resolution at lower light levels. ITT generation 2 products have a light amplification of 30,000 & exceed generation 2+ performance. However Generation 2 has a "noisier" image than Generation 1.
An almost 100% secure way to tell if a night vision device is 1st. or 2nd. generation is to switch the unit off. If the picture disappears instantly the chances are that it's second generation. If it stays lit it's generation one. Claims that generation 1 products amplify light by thousands of times, whether 1,000 or 30,000 should be treated with caution, there is the highest probability that someone is lying!
How much can I see?
This question is extremely hard to answer. Since the units are multiplying the small amounts of light that are always present you will see more and further as light levels improve. ITTs published information for Gen 2 says you can see a 6 foot man at 675 yards in full moonlight, 590 yards with a half moon, 330 yards in starlight and 100 yards in overcast conditions. With Gen 1 you can more or less halve all these figures except that with a decent infrared illuminator you can keep the minimum distance of 100 yards.
At sea, looking for commercial shipping, beacons, headlands etc., or counting the flashes of otherwise too distance marks, the land based rules of distance are considerably extended. Additionally a target yachts masthead light provides on board illumination for your scope to amplify.
Magnification, do I need it?
Every time magnification is added the light entering the unit is reduced, so it becomes less efficient. Also, the main aim of night vision is to replace your daylight vision, not to provide an alternative to binoculars. However, if you wish to look at small animals or distant large ones some magnification is essential.
Most 1st. gen. products provide a compromise, usually around 2x or 3x, but with more expensive Generation 2 models alternative lenses are often an option to give you choice.
Monocular or Binocular
Because we are so used to binoculars we tend to look down on monoculars, but they have many advantages. They take up less space and so fit more easily in a coat pocket. There is no eye width adjustment to worry about, and only one dioptre correction. These points make a monocular much faster and easier to share with someone else. Keeping both eyes open with a monocular maintains your natural night vision, so you can still see to move, or if a yachtsman, to steer, after using a monocular.
Binoculars, (or more usually bi-oculars using both eyes to view the image from a single tube), are more comfortable and so better where long term surveillance is necessary. Also they have a shape and method of use we are used to and many people like this.
More information?
Check out the Optics and Night Vision section of our web site for details of the current products we are offering for sale. You might like to look at our Century Night Rover; the Century brand name belongs to Allgadgets and On-line-marine.