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Weatherproof or Waterproof?

Weatherproof, rainproof, climateproof, rustproof, fogproof, waterproof, sprayproof—terms that manufacturers use to inform us that some attempt has been made to seal binoculars or spotting scopes against the elements. They all sound great and conjure up images of a trustworthy optic pitted against the forces of nature, but what do they really mean to a birder?

That depends entirely on the manufacturer; there is no standardization in the industry when it comes to describing how optics are sealed. What is waterproof to one manufacturer may be merely rainproof to another. And to make matters worse, manufacturers are less than forthright in defining these terms.

This is unfortunate because sealing is an important feature in binoculars and spotting scopes. An optic that is poorly sealed is subject to internal fogging as water vapor in the air condenses on interior lens surfaces. (All optics are subject to external condensation, regardless of sealing.) Fogging does not require exposure to rain or submersion in water; it can just as easily be caused by high humidity and/or changes in temperature. A poorly sealed optic also will allow dirt and dust to collect on internal surfaces, which will eventually reduce its performance and lifespan.

Internal fogging may clear up after a pair of binoculars or a spotting scope has been allowed to dry out, but the fix is only temporary. Once an instrument has fogged, it will definitely fog again. Seals do not repair themselves—they require the attention of a qualified technician, who unfortunately does not make house calls. (Don't even think about trying it yourself.)

The extent to which an instrument resists fogging, as well as dust, depends not only on the type and degree of sealing but also on how much care you are willing to give it in the field.

Ordinary binoculars and spotting scopes can survive a lot of exposure to the elements if you are willing to give seals and gaskets a little help now and then.

One way is to use a few simple accessories out in the field. Put rain guards and lens caps to work in wet or dusty conditions, and protect all optics with a good waterproof case in severe conditions. Use neck straps religiously—this is still the best way to avoid the dings and bangs that loosen seals and other internal parts.

Avoid temperature extremes. Rapid and/or extreme temperature fluctuations probably fog more instruments than exposure to rain and snow. Never store optics in your car. Day to night temperature fluctuations put enormous stress on seals and gaskets (and vehicles are a favorite target for thieves).

Cold weather also calls for a few simple precautions. Put your binoculars or spotting scope back in its case or seal them in a plastic bag before entering a warm house. Then allow it to return to room temperature before removing it from the case or bag. Any condensation will thus form on the bag or case rather than your optics. You can also avoid condensation in the field by carrying your binoculars on the outside of your coat, away from your warm body.

Reasonable care, of course, can protect optics up to a point—the rest depends on the seals and gaskets. Because sealing is internal, you cannot tell at a glance how well an optic is sealed (armoring has nothing to do with sealing).

In general, individual eyepiece focus binoculars and center focus binoculars with internal focusing mechanisms are easier to seal than binoculars with external focusing mechanisms. Spotting scopes are less consistently predictable, but roof prism binocular models are generally easier to seal than Porro prism models. Keep in mind, however, that design itself does not guarantee how well an optic is sealed. The best sealed optics are advertised as waterproof, and perhaps rustproof as well, but always waterproof. If you want the best in protection against the elements, insist on an optic that is guaranteed and advertised to be waterproof—not sprayproof, rainproof, or any of the other "proofs." If in doubt as to the manufacturer's claim, be sure to check before you buy. A high price tag does not guarantee an optic to be waterproof.

A waterproof instrument is desirable for birding, even if your binoculars or spotting scope is rarely exposed to harsh elements. The word "waterproof" tells you two things about an optic.

First, it means that the optic has received a maximum measure of sealing: It's the manufacturer's way of saying that a particular model has received additional protection for long-term use. Think of it as insurance for your investment. Why pay big bucks for an instrument that is not well sealed, especially if you observe in the tropics, around water, or in dusty, sandy areas?

Second, "waterproof" has definite implications in a warranty—most manufacturers will not charge to reseal an instrument advertised to be waterproof, but will charge to reseal an instrument merely advertised as weatherproof, climateproof, or some other proof.

Of course, this assumes you haven't driven your truck over your spotting scope or binoculars or stored them at the bottom of a lake for the winter. Most warranties cover only defects in materials and workmanship, not normal wear and tear, and definitely not abuse.

If you ever need to have an optic repaired, you will quickly learn that a manufacturer's commitment to customer service is much more important than any warranty. Talk to your fellow birders about their experiences with various manufacturers. They will know better than any expert who deserves a reputation for quality service.