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It is quite possible to give yourself the ability to see fairly clearly in low light levels, such as dull moonlight, for a few seconds. Although not exactly the equivalent of an image intensifier, using this technique can be very useful for when you drop your keys in an unlit country road, or for seeing where you are going in a dark place.

To try this you will need one piece of equipment; a small torch (be careful not to use an led torch as it can damage your vision), however if there is a single bright light source, such as a light bulb, or even a car headlight, you could use that instead. I can hear you asking why you would need to see in the dark if you have a torch? Well, this works by intensifying your whole field of vision, so i am assuming that either your torch is too weedy, or the light bulb or car headlight is not shining where you want to see.

This is how it is done:
First cover one eye tightly with your hand so that no light at all can be seen. Then stare fully into the bright light with the other eye, for a good few minutes, three at least, the aim is to get the iris of this eye to contract to the smallest size possible (be sensible though, if the light is too strong it will probably do some damage).

Now close the brightly lit eye and cover it. Turn to face the view that you want to see, and open the eye that was kept dark, the one with the fully dilated iris. You should get 10 or 20 seconds of good vision in light conditions that you ordinarily could barely make anything out.
It is important that you don't use both eyes when you look into the dark, as the eye that has been looking into the light will see very little indeed and cancel out the effect. If you don't see what you are looking for you can do it again straight away.

I was given this tip, for some strange reason, by two serving soldiers on a remote beach in Northern Crete, who had got there at night across rocky terrain using a keyring torch.

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