Optics; Rangefinders, Monoculars and Binoculars

   Binoculars, or comonly refered to as field glasses, are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction. This allows the viewer to use both eyes when viewing distant objects.

   Binoculars give the user a three-dimensional image of the subject with an impression of depth. Most binoculars are sized to be held using both hands.

   Monoculars are essentially half of a binocular and produce a two-dimensional image for the user. In most cases for the backpacker, this is sufficient. Volume and weight are therefore less than half of those of binoculars with similar optical properties, making the monocular easier to pack and carry than the larger binocular. 

   If this is going to be your first binoculars or monocular, as the case may be, you will encounter a vast range of choices may seem overwhelming at first. But rest assured, once you’ve given some thought to what you want your binoculars to do for you, and determined a target price range; you will have narrowed down your selections significantly.

   You will find a wide price range for binoculars, from $20 for the lowest-end pairs up to $1,600 and up. So you need to have an idea of how much you want to spend for your new optics.
   Just like your basic backpacking and survival equipment, your binoculars are a long-term investment. If you’re going to use your binoculars a lot, a higher quality may be the way to go.

   As you narrow your choices, look for a binocular / monocular that is sturdy, easy to focus and has the magnification (power) appropriate for your purposes. That 12x pair might give you a great view but the 8 or even 7x is almost as good and will be much lighter in your pack.
   Always opt for coated lenses. The coated lenses lessen unwanted reflection and assist light transmission to the eye.

   As you consider various optics you will find that all binoculars and monocular are described with two numbers. The first number refers to the magnification, or “power,” and the second refers to the diameter in millimetres of the objective lens. The larger the objective lens the more light is gathered.

  The quality of glass used in the binoculars prisms will determine the light transmittance, colour fidelity and clarity of the image. There are currently two types of glass prisms in use, Bk-7 which uses the element Boron to modify the glass, or the superior Bak-4 which uses Barium to modify the glass. Especially for use on the trail, a binocular or monocular that has body armor will stand up to more wear and tear.

   Whatever binoculars you decide that best fit your needs for magnification and weight, be sure to buy quality binoculars or monocular and you will not be disappointed.