How to clean binoculars without scratching the lenses

The 3 steps in order

Audubon's sequence is short, and Nikon and Vortex follow the same logic. Remove loose material first, then use liquid, then wipe. Skipping the first step is the usual way a lens gets marked.

1. Brush or blow off dirt. Audubon names a soft camel hair brush or compressed air. Nikon names a soft oil-free brush for dust and sand.
2. Lightly spray a soft lens cloth with an isopropyl alcohol-based cleaner labeled safe for coated lenses. Audubon says to never spray the binoculars themselves.
3. Wipe gently. Nikon adds that fingerprints come off with oil-free lens tissue or a soft cotton cloth lightly dampened with absolute alcohol.

Why the order protects the glass

Nikon says coating is applied to both surfaces of the lens. A multilayer coating is usually 3 to 5 layers thick, so the surface you are wiping is a thin stack of film, not bare glass. Sand or grit pressed into it by a cloth leaves lines.

That is why Nikon puts the brush first for dust and sand. If you are comparing models for their glass quality, best binoculars compared shows which ones carry ED glass, 146 of the 554 models in the catalog.

What Vortex adds for the body and heavy dirt

Vortex describes the job as starting big and working toward the smaller details. Blow off loose debris with an air duster, then wipe the exterior with warm soapy water.

Next, brush off what remains with a lens pen. Vortex then rinses heavily soiled lenses, or uses a pretreated lens cloth on lightly soiled ones. Soapy water is for the barrels and rubber armor, and Audubon lists detergent among the things to keep off the lenses.

What to keep away from the lenses

Audubon names the items to avoid: tissues, paper towels, saliva, Windex, ammonia and detergent. Nikon agrees on tissue and also rules out velvet cloth.

The cloth you use should be oil-free and soft, because Nikon's fluid recommendation is absolute alcohol on oil-free lens tissue or cotton. A shirt hem fails that test. It carries skin oil and trapped grit, and it smears rather than lifts.

Coatings and why the cleaner matters

Celestron defines fully multi-coated as multiple layers of optical coating on all air-to-glass surfaces. The RSPB shop calls that ideal. A cleaner labeled safe for coated lenses is the one Audubon asks for, because a harsh solvent attacks the layers that give those lenses their brightness.

Celestron also lists plain coated, which means one or more surfaces carry a coating, and fully coated, which covers all air-to-glass surfaces. Whichever label your pair has, the cleaning steps stay the same.

Water, seals and cleaning the outside

Celestron defines waterproof as sealed and filled with dry inert gas, usually nitrogen. Nikon says its waterproof binoculars keep the body airtight with nitrogen to prevent fog and mold, and that they should not be used underwater.

Nikon lists the 8x30 PROSTAFF as waterproof down to 3.3 ft. Even so, a sealed body is cleaned the same way: rinse and soapy water for the shell, cleaner on a cloth for the glass. Celestron adds that weather-resistant pairs have minimal openings that can let water in, so keep liquid away from the lens rims on those.

Keeping lenses clean between sessions

The lowest-risk cleaning is the one you rarely need. Audubon's first step, a brush or compressed air, handles most of what lands on a lens in the field.

If you shop for a pair that is easy to look after, the best binoculars for birding list covers sealed bodies, and binocular harnesses keep the lenses off tables and car seats.