Tool paradise since 1999
Each pair of binoculars comes with a numerical
specification, such as 8x42. The first number (in this case, 8)
indicates the magnification of the binoculars. In this example, the
subject is brought 8 times closer to the viewer. If a subject is
located 80 metres away, you will view this subject as if it were
only 10 metres away from you. The second number indicates the
diameter of the objective or
front lens, measured in millimetres. The higher the number, the
more light that enters the binoculars and the lighter the image
will be. This is a very important factor to be considered when the
binoculars are to be used in poor or low light conditions (See also
'Clarity and brightness' and
Determining the magnification factor
It is quite tempting to want to purchase binoculars with the highest magnification factor possible. After all, the stronger the magnification, the better you can see your subject. And yet this is not actually the case. First of all, the magnification factor has a direct effect on the exit pupil, the twilight factor and also the relative brightness.
The stability of the binoculars also presents a problem. Not only is your subject magnified, but so are the movements made by the binoculars. Compare this with a camera. Using a wide angle lens and longer shutter speeds, you can take photos without motion blur. But with a telephoto lens you can't.
Magnification factors starting from 10x affect our ability to hold binoculars steady enough for the image to remain fairly still. It is therefore essential to use a tripod or an image stabilisation system.
Furthermore, binoculars with a high
magnification factor generally tend to be heavy and rather
cumbersome and so they are quite a burden to carry around and use.
Your binoculars may well be of really top-grade quality, however,
if they are just lying on the table at home because they are simply
too heavy, then they obviously do not come up to scratch. If this
is the case, you need to compromise!
In general, as the magnification increases,
the depth of field decreases. This fact is one of the disadvantages
of binoculars with high magnifications. At very high
magnifications, the depth of field can be so shallow that precise
focusing is critical. This is another factor that requires careful
consideration. In conclusion, large binoculars very often come with
a high price tag. It is just as well that you only feel this pain
Average magnification:7-10x, general use
High magnification: >10x