Monoculars and binoculars are both optical instruments that allow you to magnify and view distant objects. Although they both share the same telescopic technology, and you can for use them for the same purpose, they have different features. Before you choose between the two, look at their advantages and disadvantages and how they compare to make it easier to decide which instrument best suits your needs.
One Eye or Two
The most obvious differences between monoculars and binoculars are the way they look and the way you use them. Monoculars look like small telescopes. They have a single lens that you hold up to one eye -- you choose which eye to use. Binoculars have two lenses, and you need to hold the device in front of both eyes to look at objects. If used for long periods, you may find that binoculars are easier on your eyes compared to monoculars because they don't put a strain on just one eye.
Size and Weight
Monoculars are typically much smaller and lighter than binoculars -- the smallest can be thumb-sized. This makes them more portable, as you can easily slip a monocular in your pocket or bag and carry it with you wherever you go. Binoculars are heavier and take up more space, so you may not want to carry them at all times without advanced planning. This may lead to lost opportunities to view things when you spot them by chance.
Although monoculars can give a clear and detailed magnified viewing experience, you may find this a bit flat compared to the view you get through binoculars. You get a visual acuity advantage with binoculars because you use both eyes -- this typically gives better overall depth, distance and three-dimensional viewing than with monoculars. However, you may have to calibrate both lenses individually on binoculars to get good focus, as your sight in each eye is not likely to be the same. You only have one lens to deal with when you're using monoculars.
Uses of Monoculars and Binoculars
Monoculars and binoculars are typically used in hobbies and sports, such as birding and hunting. Monoculars also have a couple of additional applications. For example, you can adapt some models into rifle scopes and range finders. They can also be a useful visual aid for people with poor eyesight. They can help people discreetly read signs and directions at a distance, and, if you turn a monocular upside down, it also works as a magnifier.