Binocular Fundamentals

Bob Peterson, Wildlife ecologist and L.L. Bean Visual Merchandising Lead, interacts with attendees at a recent L.L. Bean Outdoor Discovery School Birdwatching and Binocular Fundamentals Clinic at the Mall of America. Photo © 2017 Kelsey Wotzka

Welcome in!

It’s been a little while since I’ve reached out… thanks for checking out this edition of Zero528! Enjoy!

Birding is Fun and Easy
If I’ve inserted one main take away message for this blog, this is it!

To begin to understand the joy in birdwatching it is imperative to first cover the basic features and operations of binoculars – a key piece of equipment for the outdoor enthusiast and birdwatcher.

Unfortunately, I can’t show “how” to operate a set of binoculars, but I suspect my readers are a sharp group, and I’ve added a few resource links to aid in discovery.

Eastern bluebird (Sialia sialis), perched on my backyard fence. Be certain to ‘clean out’ bluebird boxes each spring to insure these beauties make use of the cavity nesting opportunity. Photo © 2017 R.L. Peterson

Objective of this blog:

• Understand basic types and use of binoculars

Binoculars: Fundamentals and Features

Image © NikonSportOptics.com

Binoculars: How to Choose
A wide range of prices exist on similar-looking styles. Understanding binocular specs, such as magnification and objective lens diameter helps narrow down which pair works best for specific needs.

Binocular Size:
• Full-Size (common specs: 8 x 42, 10 x 50)
Best for serious wildlife viewing and for use on boats. Full-size binoculars capture more light and perform better in low-light situations. They usually provide steadier images and a wider field of view, so they’re great for bird watching, but they’re generally too big and heavy for backpacking
• Mid-Size (common specs: 7 x 35, 10 x 32)
Best all-around choice for wildlife and sports use. While a bit heavy for backpacking, these binoculars balance moderate size and above-average light transmission.
• Compact (common specs: 8 x 25, 10 x 25)
Best for daytime outdoor activities. These are the lightest, smallest binoculars for backpacking, but they’re less comfortable during extended periods of use.

Great blue heron (Ardea herodias). I like to take along a camera in addition to other necessary equipment. Birds don’t always cooperate, but I like to use the pics as evidence of my sightings. Photos don’t have to be ‘perfect’ and are a great means of remembering the outing. Motto – better to take the camera and need/want/attempt to take a pic, than to want it and NOT have it. Photo © 2017 R.L. Peterson

Two Numbers
Binoculars are identified by two numbers which indicate:
1. Magnification power (e.g., 7, 8, 10)
2. Objective lens diameter (e.g., 35, 42, 50)
e.g., 8 x 42 binoculars have a magnification power of 8 and an objective lens diameter of 42mm
Binocular Magnification Power
A magnification power of 8 means that an object will appear 8 times closer than it would to the unassisted eye; e.g., when viewing a deer standing 200 yards away through 8x binoculars, it will appear as though it were 25 yards away (200 divided by 8).
NOTE: Binoculars with magnification powers greater than 10 amplify the movements or shakiness in the holder’s hands, making steady viewing difficult.
Binocular Objective Lens Diameter
The second number used in binocular identification refers to the diameter (in millimeters) of the objective lenses (those farther from the eyes / closer to the “object” being viewed).
Example: 7 x 35 binoculars have objective lenses measuring 35mm. The diameter of the objective lenses largely determines how much light the binoculars can gather. More light equates to a brighter view, particularly in low-light conditions.

A red-bellied woodpecker (Melanerpes carolinus) investigates a crack in this tree in my backyard – notice the foliose and crustose lichens.  Photo © R.L. Peterson

Binocular Field of View
This spec determines the width of the area (usually in feet) that can be viewed at a glance, 1,000 yards from where you stand. A wide field of view is best to find and identify objects such as birds. Usually a higher magnification power results in a narrower field of view.
Binocular Focus
Almost all binoculars feature a central focus wheel that focuses both barrels on the binoculars at the same time. They also typically include a diopter adjustment ring which focuses one barrel independently of the other. This feature compensates for differences in vision between the users eyes. Once the diopter is set, then the two barrels should stay in proper relation. From then on, focus by turning the central focusing knob.
The diopter ring is usually located on either the left or right barrel near the eyepiece.

Stay tuned for my next exciting blog- Birdwatching Fundamentals.

“Enjoy and keep a good thought!” Bob P.

Additional resources:

L.L. Bean

Nikon

All About Birds

 

 

 

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