Binoculars

What do the numbers mean?

Binoculars come with numbers like 7x50, 8x29, 8x40 or 10x50. The first, lower number is the magnification; what you see through them is that many times larger than you would see with naked eyes. The second number is the diameter of the large front (objective) lens in millimeters. The greater the number the more light is captured. So the largest numbers such as 10x50 mean the highest magnification and with the greatest amount of light let in through the front lenses. Are they best for bird watching, then? Not necessarily, because 1) they are heavier than binoculars with smaller numbers and 2) they magnify movement as well. So they are best used in a stable situation when, for example, you are sitting or have them on a tripod. On the other hand 8x20 binoculars are light and easy to carry but have a smaller field of view and let in the least light. Good for backpacking but not serious birdwatching. Best for birdwatching are 7x35 or 8x40. Price? You can get very decent binoculars for less than $100. I have seen them as cheap as $9.99, but they were what you expect. Again, try before buying.

Things to consider before buying optics:
Compare several makes and models. See what feels good in your hands and what fits your face.
Examine the instrument you buy; don’t just rely on a company or a brand. There is variation in the quality, mechanical performance, and optical precision of all optics.
Do not settle for a lower-priced binoculars if they are not what you want and what you really want is outside your present budget. Tolerate the binoculars you are using now and save for the better ones. If you buy mediocre optics, you will only replace them later with the ones you really wanted.

Spotting scopes are different than binoculars in that their magnification as well as focus can be adjusted.

See All About Optics for more information about binoculars and spotting scopes.