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OH WHAT A RELIEF IT IS

I hate my glasses. I am reminded of this every time it rains, or snows, or when it is cold, or when the ragweed is pollinating, or whenever they need to be cleaned. But I especially hate my glasses when I want to look through binoculars or my spotting scope. That's when they can be a real pain, and not just in the eyes.

I'm not alone in my misery. The fact is, most people need glasses (or contacts) these days. And even people with good vision use sunglasses. The problem then, is what to do with glasses when you want to use binoculars or a spotting scope.

Many people just surrender and remove the darned things; they put them down or wear them around the neck with a safety cord. It sounds easy, but it doesn't always work, especially for birding.

Speed is important in the field, and the extra time it takes to fumble with glasses can result in a lost birding opportunity. Birds don't wear glasses, so we shouldn't expect them to understand our dilemma. As cruel as it may seem, that once-every-10-year warbler may not wait for us to remove our glasses. Indeed, that extra movement may be just the thing that makes it flee.

No, your glasses belong on your face fulltime, unless you use them only for reading. My friend learned this the hard way. He was in heavy grass when he removed his glasses to observe a bird and—you guessed it: We combed the underbrush on hands and knees for more than an hour in search of those glasses, and finally gave up when it got dark. Being nearly blind, he never would have managed the drive home if he had been alone.

Your glasses also belong on your face if you have astigmatism. Defects like nearsightedness and farsightedness can be corrected by focusing the binoculars, but not astigmatism. With this condition you need to wear your prescription glasses when you watch birds, or you will sacrifice valuable image sharpness. It makes no sense to pay big bucks for optics, then use them when your eyes are not at their best. If you're not sure about your prescription, ask your eye doctor.

Contacts are the most frequently used alternative to eyeglasses, but they, too, have drawbacks. Many contacts require constant blinking to keep them moist, but most people tend to stare, instead of blink, when they observe. This leads to filmy vision as the contact begins to dry out. Then, as the observer blinks rapidly to correct the problem, the eyes momentarily run with fluid, which further degrades the image. Also, many contacts that correct for astigmatism are not as sharp as eyeglasses. I have yet to find contacts that work well for me, but then I have terrible eyesight.

For most people, then, the best solution is to observe with glasses. This is a workable approach as long as your binoculars or spotting scope features something called long eye relief. This feature allows you to see the entire field of view, even when wearing glasses. By contrast, models with short eye relief, and there are many of them, yield a much reduced field of view when used with glasses. This is an uncomfortable situation, and entirely unnecessary.

The amount of eye relief varies with eyepiece design. Poor (short) eye relief designs require the eyes to be relatively close to the eyepiece to see a full field of view. Glasses, of course, prevent this. They simply keep the eyes too far back from the eyepiece to see all the field that eyepiece has to offer. In really short eye relief design, this loss can exceed 50 percent of the available field.

By contrast, long eye relief designs are more forgiving. The eyes can be well back from the eyepiece and still see a full field of view. If you wear glasses, you will notice the difference right away. Compared with a short eye relief optic of the same magnification, the wider field of view will be immediately apparent.

This full field of view is a real advantage. It improves both performance and comfort; the eyes are more relaxed, and vision improves. When an eyeglass wearer experiences this in binoculars for the first time, it's as if a curtain on a window has been opened. And with all the long eye relief models available today, there is no need for any eyeglass wearer to settle for less.

Long eye relief model binoculars are usually identified as such by the manufacturer, because this is a good selling point. European brands often designate long eye relief with the letter “b” in the model designation, whereas most Asian manufacturers simply list long eye relief as a feature.

Eye relief may also be listed under the technical specifications where it is expressed in millimeters. In general, an eye relief of at least 14 to 15mm is needed for the average eyeglass wearer to be comfortable. Personally I prefer something in the 16 to 17mm range, but I can tolerate something as short as 13mm when necessary. For me, anything less is simply not worth the hassle, no matter how otherwise excellent the optics. Also be advised that some manufacturers may consider an eye relief as short as 13mm to be long eye relief. Check before you buy.

If the information is not available, you can usually spot long eye relief binoculars by the depth of the fold-down or retractable eyecups. Most long eye relief binoculars have tall, or deep eyecups, whereas short eye relief models have skimpy, shallow eyecups. But to be sure, you should do a before and after test (with and without eyeglasses) to see how field of view is affected. Just remember always to fold down or push in the eyecups when observing with glasses.

As you scan the various models for their eye relief, you will probably notice a pattern. There are more 7x and 8x long eye relief binoculars available than 10x long eye relief binoculars. And you will find more full-size long eye relief binoculars than compact ones. As an eyeglass wearer, I personally consider eye relief to be more important than magnification, but the choice is yours.

Long eye relief is truly a wonderful feature for birders who wear glasses when they observe. I, for one, would be lost without it.

But I still hate my glasses.