The two main types of binoculars, as well as the various advantages and disadvantages of each type, were discussed in a previous post. The main objective of this post is to give you some pointers on effectively adjusting and using your binoculars in the field. Ultimately, you will learn more about binocular use by practicing with them in the field, but this post will give you some basics to get you started. You’ll first learn how to adjust your binocs, and then we’ll cover the two field methods for using them to spot wildlife and other subjects.
Adjusting Your Binoculars
Taking a few minutes to do two simple adjustments will make a world of difference in what you see through your binoculars. You are aiming for an oval-shaped field of vision when looking through them. Here’s how to achieve maximum performance.
The first adjustment needed is to align the exit pupils of your binocs. Look through your binocs and then draw them away from your face, about 12 – 18 inches. You should see two circles of light through the ocular lenses (the lenses that are closest to your eyes when using your binocs). These are the exit pupils. You will want to adjust them so the distance between them is equal to the distance between the pupils of your eyes. The easiest way to do this is to start with the exit pupils as close as possible, look through your binoculars and expand the distance between them until your field of view is maximized.
The second adjustment compensates for any vision difference between your right eye and left eye. This is done using your binoculars’ diopter ring. On roof prism binocs (see previous article/link) the diopter is often located on the center focusing ring, between the binoc’s barrels. On Porro binocs, the diopter is often found on the right eyepiece. To make this adjustment, look through your binocs with only your left eye—close your right eye. Use the center focusing ring to focus on a distant subject so that it is clear to your left eye. Once you’ve done that, be sure not to change the center focus ring. Keeping your left eye open, open your right eye and turn the diopter until the subject appears focused with both eyes. Voila! You’re done adjusting your binocs.
Using Your Binoculars
While using binoculars may seem self-evident, there are a couple of tried-and-true techniques for efficient binocular use—especially when using them to locate wildlife in large expanses, such as pack ice, along shorelines and bird cliffs.
Set your binocs on the most distant setting (infinity) and slowly sweep the landscape from one side to the other watching for subjects of interest. Adjust the magnification level and continue scanning. I’ve stood in groups of several dozen people all scanning the horizon and I’ve been amazed at the skill some of our expedition staff have at using binocs. Almost invariably they were the first to spot polar bears in the pack ice or whales spouting in Antarctica. This supports the idea that your binoc skills improve with use—so practice whenever possible.
Say you’ve found something while scanning with your binoculars, or perhaps with your naked eye. Now you want to zoom in on the subject to get a better view. Don’t take your eyes off your subject! If you spotted the subject while scanning, it’s pretty obvious that you can simply increase your magnification and refocus to your liking until the subject is clear and enlarged in your field of vision through the binocs. But what if you spot something without using your binocs and want to get a closer look? Keep looking at the subject and slowly raise your binocs to your eyes. You have a much better chance of finding the subject through the binocs if you don’t move your head or eyes while doing this. Again, the name of the game is practice!