Binoculars are referred to with 2 numbers, such as 7 x 35 or 10 x 50. The second number is the diameter of the main (objective) lenses in millimeters; 7 x 35 lenses are 35 millimeters (1. 38 inches) in diameter, while 10 x 50 lenses are 50 millimeters (1. 97 inches) in diameter. While binoculars with relatively small magnification factors produce images that are less magnified than those produced by binoculars with higher magnification factors, these images will be sharper and your field of view (how widely you can see) will be wider. If you need a wide field of view, such as for viewing a football game from high seats, choose a lower magnification.
Note that the higher the magnification of your binoculars, the dimmer the image will be. Although the image you see will be larger, your field of view will narrow and it’ll harder to keep the image focused. If you choose binoculars with 10x magnification or greater, get a pair with a tripod socket so you can mount and steady your binoculars when needed. If you’re hunting in a forested area, you may find that binoculars with a 7x to 10x magnification factor are more appropriate.
If you’re more interested in seeing the details on smaller birds at greater distances, then you may want to opt for binoculars with larger magnifications and smaller lenses. Note that the larger the lenses are, the more the binoculars will probably weigh. Generally speaking, standard-sized binoculars have objective lens diameters larger than 30mm, while compact-sized binoculars have lens diameters smaller than 30mm.
Think about how you intend to use your binoculars; a pair you intend to keep at home to look out the window don’t need to be as durable as a pair you want to take hiking with you.
You can compensate for the weight and stabilize the binoculars by mounting them on a tripod or with a strap that lets you carry them around your neck How you intend to use the binoculars is especially relevant here. If you plan to carry them around your neck while hiking, heavy binoculars may be a real burden.
Note that waterproof binoculars are usually more expensive than water-resistant binoculars.
Note that glass lenses are also typically more expensive than plastic lenses. Binoculars made with Extra-low Dispersion (ED) glass produce the most high quality image, though these are also one of the most expensive types of lens material used in binoculars. Lens coatings are described with the following codes: C means that only some surfaces have been coated with a single coating layer; FC means that all glass lens surfaces other have been coated; MC means that some surfaces have been coated with multiple layers; and FMC means that all glass lens surfaces have been coated with multiple layers. Multiple-layer coatings are generally superior to single coatings but add to the cost of the binoculars. [9] X Research source
For example, binoculars with plastic lenses are the best choice for activities such as hiking and mountain climbing, or for children who are handling binoculars for the first time. Note that while plastic lenses are generally inexpensive, a set of plastic lenses that provide the same image quality as a set of glass lenses will cost more.
Many binoculars include rubber eye cups around the eyepieces to help you seat the eyepieces over your eyes when using the binoculars. If you wear glasses, look for binoculars with eye cups that retract or flip out of the way. [12] X Research source
Binoculars focus in 1 of 2 ways. Most binoculars have a center-post mechanism, as well as a diopter corrector in case one of your eyes is stronger or weaker than the other. Waterproof binoculars, however, usually have individual focusing for each lenses, with controls on each eyepiece. To adjust binoculars to your eyes, close your right eye and focus your left eye on a distant object using the central focus. [14] X Research source Then close your left eye and use the focusing ring on the right eyepiece to focus your right eye. This compensates for the difference in strength of your eyes. [15] X Research source Some binoculars are “focus-free,” with no ability to adjust the focus whatsoever. These binoculars can cause eyestrain if you attempt to focus on something closer than the pre-set distance.
Less expensive binoculars use BK-7 prisms, which tend to square off one side of the image, while more expensive binoculars use BAK-4 prisms, which deliver more light and sharper, rounder images.
If you buy an expensive pair of binoculars and they become damaged, having a warranty or guarantee from the manufacturer would make it much easier for you to get them replaced.
