BINOCULARS
Binoculars Explained:
How to Choose a Good Pair By Bruce Pierce
I
believe that binoculars are one of the most important navigational tools on a boat. Yet, I have always been amazed at the amount of confusion there is in boating about binoculars. Most boaters, and even a lot of professional captains, don’t understand what the numbers represent or how they will affect their usability. One of the biggest problems adding to the confusion, is that people tend to buy very inexpensive binoculars, thinking that this is an easy place to save money. But what happens is the binoculars are so poor that it’s very hard to see anything. What happens is the binoculars end up in the chart drawer, not being used, and the skipper, standing on the dock, tells his buddies, “Binoculars are useless on a boat.” A good friend of mine, who worked for a great binocular manufacturer, Leica, explained to me what you’re paying for. A person goes to an eyeglass store to buy a pair of glasses. The eyeglasses are just two pieces of glass, or plastic, and the construction of the frame is not that complex. Yet it is common to pay $300 - $400 for an ordinary pair of glasses. Then she asked me how much I paid for my Maui Jim sunglasses. I told her around $200. She asked why did I pay so much for the sunglasses when you can buy a cheap pair for a lot less than that, right off the rack. I told her, because when I used those inexpensive sunglasses, I got headaches after using them on the water. She said “That’s the difference between good glasses and bad.” There is a lot more work that goes into the construction of binoculars than eyeglasses. A typical binocular might have eight to twelve pieces of glass, or mirrors, on each side. Each piece needs to be perfectly aligned, using laser precision. The glass has to be ground with laser precision. And the glass needs to be coated to help the light reach your eyes. Both left and right cylinders need to be the same, and there has to be an internal focusing system to keep the moisture out. When you think about it, doesn’t it make sense, that if
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April 2005
SOUTHWINDS
eyeglasses cost $300 - $400, then a good pair of binoculars would cost more than that? A quality pair of binoculars ends up on your neck or in the cockpit, instead of down in the chart table. When you go to use them, you can actually see what you’re looking at, and the benefits become obvious. Imagine being able to see something seven, or even 10, times closer. Your eyes have to be one of the best navigational tools you have on a boat, and you can make them seven to 10 times stronger. What Does 7 x 50 Mean? Now, let me explain what the numbers mean, and how they affect you, the boater. Numbers like 7 x 42, 8 x 25, 10 x 50, or 7 x 50. The first number represents the amount of magnification. How much closer the subject will be to you. For example, a 10 power, or magnification, will make a subject that is a thousand yards away (10 football fields) look as if it was only 100 yards away (one football field.) So, following the same formula, a seven magnification would take a subject that is 700 yards away and make it appear to be 100 yards away. How does this affect you, the boater? You would think, by this example, that the higher power would be better. But, the more magnification, or let’s say, the higher first number, the steadier the binoculars have to be held, and the platform you’re on has to be stable. Well, most sailboats aren’t very stable. So, to be able to use a binocular you need a low first number, like a seven. This is one of the biggest problems: Boats are not steady and people buy too much magnification, while also buying poor quality binoculars, making them very hard to use. But a high quality binocular and a low magnification, like a seven, solves this problem— really pretty simple. If your vessel is very stable, and large, maybe over 70 feet, you could use a stronger pair and get away with it. But since you’re probably using your naked eye right now, and your inexpensive pair is down below doing you no good at all, being able to bring a subject seven times closer is quite an improvement. The second number represents the diameter, in millimeters (mm) of the front lens. The larger the front lens, the more light enters the binoculars, making the image brighter and clearer. How does this affect you, the boater? Probably not a lot. If the lenses are properly set, ground, and coated, you probably will have enough light to have a clear and bright image. But, to give you an example; if you were stargazing, a higher second number (42/50) would allow you to see more stars than, say, a lower number (25/32). Or, if you were bird watching, the trees are very shadowy, with a higher number, you would be able to pick out the birds easier. Most of what the boater is looking at—markers, other boats, and the like—you should have no problem with a quality pair of glasses. www.southwindssailing.com