Clean a lens only when it actually needs it — not on a fixed schedule.

A little dust on the front element usually has little or no visible effect on photos, because it’s tiny and far out of focus. So if you don’t see fingerprints, smears, or debris affecting images, it’s usually best to leave the glass alone.

If the lens does need cleaning, modern lens glass and coatings are generally durable enough for normal cleaning with proper tools, such as a clean microfiber cloth or lens pen. The main risk is rubbing grit across the surface, so first remove loose dust or sand before wiping, and avoid ordinary tissues or anything abrasive.

In short: don’t clean routinely; clean when there is visible dirt, fingerprints, or marks that could affect image quality. If you want extra protection, some photographers use a clear or skylight protective filter so any wear happens on the filter instead of the lens itself.