To keep the riflescope usable for a long time, the objective and eyepiece should remain intact. Scratches on the lenses and damaged coatings cause light loss and irritation. “Cleaning” with the jacket sleeve or a handkerchief is not a good choice, as the grease and dust particles you carry with you smear and damage and cloud the lenses.
The telescopic sight caps reliably protect the lenses and should be put on after use. For transport, the riflescope should be protected from contamination and mechanical defects by a protective bag, a soft sleeve, or removed in a box, in addition to the protective caps.
Impurities and residues on glass surfaces cannot be avoided in nature or on the shooting range. An eyepiece quickly picks up dirt from eyelashes, flakes of skin or grease, and residues of dust and water can be deposited on the lens.
So cleaning has to be done in any case, the only question is how. Important: Read the manufacturer’s instructions for cleaning. The hard particles should be carefully removed from the glasses before the lenses can be cleaned further. There are waterproof riflescopes that can be held under the tap; others are worked on with a lens brush.
Carefully remove dust and hard-edged particles
A lens brush or a blower can be used to remove loose dust and coarse residues. Here, carefully remove even the finest grains of dust before any further cleaning of the glass surfaces, as otherwise, micro-scratches can occur. For waterproof telescopes and binoculars, lukewarm water can also be used to remove grease-free dirt.
Eliminate severe contamination
To protect the lenses, fingerprints, water, and oil stains should be removed immediately. Otherwise, the coating can be damaged. Cleaning with solvents is not recommended, as these do not remove the dirt but rather distribute it. It is better to clean with unscented soap or another suitable cleaning agent, which removes the dirt from the glass surface without damaging the coating. When the contamination has been removed, the optics can be cleaned with distilled water and alcohol.
Acetone can be used for dirt that is difficult to remove. It is important to keep the acetone away from the rubber coating.
Oil and fats on the lentils
Oil and grease attack the coating and should be removed quickly. The use of alcohol, acetone, or a lens cleaning agent with a lens cloth removes the stains. All residue should be completely removed from the optics.
Remove fingerprints on the lens
We recommend using a microfiber cloth to remove fingerprints from the optics. Breathing on the glass surface, followed by a light, a circular wipe is often enough to remove annoying marks. The use of paper towels and cleaning powder, however, is not recommended.
Water and limescale residues
Deposits of raindrops and saltwater leave crusty deposits on the optics. These should be moistened before removal and then removed with a cleaning cloth.
Fungal attack in and on the glass
A fungal infestation, also known as a fungus, is impossible with a waterproof glass filled with dry nitrogen inside a riflescope. When colonized, the fungus is visible through a fine, branch-like structure on the lens. The metabolism of the spores causes permanent damage to the glass and coating.
If the glass is stored in a warm, humid environment, fungal growth can also appear on the lenses. Soiling on the lenses provides an optimal breeding ground for fungal spores. Storage in airy, bright rooms is particularly recommended in tropical areas. Exposure to the sun removes moisture residues and effectively prevents fungal infestation.
Alcohol, acetone, and other cleaning agents
Pure alcohol can be used to clean high-quality, multi-sealed glasses. However, acetone or other solvents is dangerous because they can attack and damage various materials.
Storage in winter and at sub-zero temperatures
After staying in the snow and at low temperatures, cold binoculars or telescopes should be kept in a dry, well-cooled room, otherwise fogging will set in immediately.