You probably remember the great discovery of magnifying glasses and other lenses when you were a kid. Who can forget using their first magnifying glass to burn dry leaves, ants and anything else that managed to wander under their lens? Well, you may not have realized it then, but you were practicing some very useful survival techniques.
The exact same methods that you used back then could save your life some day. Just grab the closest lens you have, whether it comes from a magnifying glass, a pair of prescription glasses, your binoculars or a camera lens (the removable kind used on high dollar cameras) and you’re set.
The trick to using any lens is focusing the light into as small a point as possible. That means you have to determine the best “focal length” for that lens. This important figure is the ideal distance between the lens and your tinder. In most cases, you will find that the focal length is actually rather short. So, if you’re having trouble making your white-hot point of light, then move your lens closer to your tinder.