Modern scopes and binoculars have multi-layer coatings that make the image bright and sharp. Those coatings are delicate. Most lens damage comes from wiping grit across the glass with a shirt sleeve, not from use.
Cleaning the lenses
- Remove grit first. Use a blower bulb or a soft lens brush to get rid of dust and sand. Wiping before this step is how lenses get scratched.
- Apply cleaner to the cloth. Spray Ballistol Optics Cleaner onto a clean microfibre cloth, not straight onto the lens, so it can't seep behind the lens edge. It was developed with Leica Sport Optics for high-quality optics and is safe on plastic lenses.
- Wipe gently in a spiral from the centre outwards, with very light pressure.
- Finish with a dry part of the cloth. Repeat if there are smears.
Don't use glass cleaner, alcohol wipes, tissues or paper towel, which can damage coatings or leave fibres. And never use gun oil on the glass.
Rain, fog and fingerprints in the field
Keep flip-up lens covers closed when you aren't using the scope. If rain spots the lens, let it dry rather than smearing it, then clean when you're back. Fingerprints come off with optics cleaner and a microfibre cloth.
Mounts, rings and turrets
Scope rings, bases and turret caps are steel or aluminium and can corrode from sweat and rain. Wipe them with a lightly oiled cloth (Ballistol) after a wet outing, taking care to keep oil away from the lenses and eyepiece. Don't oil the inside of scope rings before mounting, as it affects how the rings grip the tube.
Binoculars and spotting scopes
The same lens method applies. Clean the eyecups with a damp cloth, and wipe metal hinges and focus wheels with a barely oiled cloth if they've been out in salt air.
Storage
Store optics with caps on in a dry room, out of sealed cases if they've been out in the rain, so any moisture can evaporate.
