Dust is everywhere. As you know, DSLR cameras occasionally get dust on their sensors which is why most modern DSLRs feature shaking sensors or low-pass filters to reduce dust accumulation. Lenses, on the other hand, get dusty far more often then imaging sensors. They even get dusty while waiting to be used because the lens caps are not dust-proof. Several companies make dust-proof and weather-proof lenses which prevent dust and moisture from entering the interior of the camera and lens. However, they still let dust slowly seep through their lens cap. It is time someone made dust-proof lens caps! Make it reasonably priced and I’ll buy one for each of my lenses.