Binoculars 101: What You Need to Know to Get a Perfect Pair

Most binoculars are multi-purpose instruments, suitable for a number of different activities including bird watching, sports, concerts, astronomy, hiking, fishing, nature observation and more. Because of their light-gathering ability and the typical wider spacing of the lenses than the human eye, binocular images are brighter, more detailed and more three-dimensional than normal vision. Premium binoculars are an instrument that can give you a lifetime of satisfaction and enjoyment.


A camper learns to use a pair of binoculars.

Magnification: When you see the designation on a binocular, 7 X 35 for example, the first number, 7, is the power or magnification. This means an object that is 700 feet away will appear to be 100 feet away, or it will be 7 times larger. Binoculars for the activities listed above should be 7, 8, 9 or 10 power.

Aperture: The second number in our example, 35, refers to the diameter of the lens closest to the object you are viewing, in millimeters. For the brightest binoculars with the best color, contrast and detail, the aperture divided by the magnification should be close to 5. This is the size, in millimeters, of the beam of light that leaves the binoculars and enters your eye. It’s called the exit pupil.

Exit pupil: This, described above, should be around 5 millimeters, as that is the size of your pupil under most circumstances. An exit pupil less than 5 millimeters won’t give you all the information you need to see the subject clearly.

Size and weight: These will vary greatly. Pocket-sized binoculars are convenient and great for fishing, backpacking and activities where weight needs to be minimal. They don’t gather as much light, however, and won’t give as good a picture in low light situations. Your main pair of binoculars should be standard size with compacts for a back-up.

Field of view: The measurements of degrees you see on a binocular tell you how wide the view you’re seeing will be. Each degree is worth 52.5 feet at 1,000 yards. A binocular with a 6.5-degree field of view will have a picture that is 341.25 feet wide at 1,000 yards. A binocular with too narrow a field of view will make it difficult to find the subject, and it will be hard to keep it in your field of view.

Other factors: You should find binoculars with a good ability to focus up-close, as well as far away. They should be comfortable to carry and hold. You should always buy the best binoculars you can afford. A higher quality pair will give you a much better view of your subject.

Hopefully the information in this post keeps you from spending too much on a lousy pair of binoculars. For plenty of friendly, free advice and an excellent selection of high-quality binoculars, visit Wild Birds Unlimited. Happy Birding!

~ David Menough, Owner of Wild Birds Unlimited of Arvada

David and his wife, Kathy, own the Wild Birds Unlimited store at the southeast corner of 88th and Wadsworth in Arvada. WBU stores specialize in bird feeders, birdbaths, houses, field guides, nature-related gifts, binoculars and quality seed blends.

Other WBU Front Range locations:

  • Wild Birds Unlimited of Denver – 2720 S. Wadsworth Blvd.
  • Wild Birds Unlimited of Fort Collins – 3636 S. College Ave.

BirdTalk migrating to noon! Tune in to David and Scott Menough at noon on Saturdays for BirdTalk Radio on 710 KNUS. They will broadcast live from their stores in Arvada and Denver.

Learn more about bird-friendly living.