A Guide to Shopping for Used Binoculars
Whether you're a novice birder looking for your first pair of used binoculars, or a seasoned hunter looking to upgrade to a newer model, there are used binoculars available for every budget. The right pair for you depends on your applications. Birders, hunters, boaters, stargazers, and opera glasses users all have different viewing needs, and thus, need different types of binoculars. Understanding all the designs and specifications helps you make the right purchase.
When light passes the convex lenses of binoculars, it changes direction and turns the image upside down. Binoculars use prisms that bend the light at 180 degrees to make the image appear upright in your eyes. There are two main types of prisms used in this regard: Porro prisms and roof prisms.
Porro Prism Binoculars
These have an M-shaped design where the lenses and eyepieces aren't in line. They have wider objective lenses that give them a larger field of view, perfect for stereoscopic viewing.
Roof Prism Binoculars
This type has a more compact H-shaped design. The binocular tubes are in line with the eyepieces. Because of their lighter weight and small size, they're the most ideal choice for anyone on the go.
When searching for specifications, you'll likely find two numbers engraved or written on the casing of most binoculars. For example, you may find 10 x 42 or 8 x 25.
The first number is the magnification of the binoculars. For instance, those with a magnification power of 10 can make an object appear 10 times larger. HD binoculars can have a magnification power of up to 12x. For stargazing, use binoculars with a magnification of 20x.
The second number is the diameter of the objective lenses. The larger the diameter, the more light enters the binoculars, and thus, the brighter your images appear. This means that binoculars with a 42mm objective lens diameter offer clearer images than that with a 25mm diameter. However, they may be bulkier.