Magnification
On the upper surface of your binoculars you'll find two numbers, for
example 7X35 or 10X40. The first number is the magnification power of
the binoculars; 7X (pronounced "seven ex" or "seven power") means the
binoculars make subjects appear seven times closer than without
magnification. The second number is the diameter of the binoculars'
objective lenses in millimeters, and is related to the binoculars'
brightness.
Some birders prefer binoculars as powerful as 10X, especially for
viewing hawks, waterfowl, and shorebirds, which are likely to seen at a
distance in relatively open areas.
For general birding though, most bird watchers prefer 7X or 8X
binoculars, for a couple of reasons:
- The more powerful your
binoculars, the harder they are to hold steady for comfortable viewing.
"Hand shake" gets worse in binoculars over 8X.
- Lower power
binoculars tend to have better light-gathering ability and a wider
angle of view than more powerful models.
Avoid "zoom" binoculars, whose magnification varies, for instance from
7X to 15X. They're often bulky and heavy, and their optics are often
poor. At the higher magnifications they produce a dark image and are
hard to hold steady.
"Image Stabilizer" binoculars have moveable internal prisms that counter the vibrations caused by unsteady hands. The technology is promising, but to date these binoculars still need better optical quality and light-gathering ability.
