1, lens sealing is not good, after a long time, the lens surface will be evenly covered with a layer of fine dust, giving people a feeling of airtight. This situation is easy to clean up.

2. The aperture assembly of many lenses is not sealed, and too much damping grease is used in the focusing assembly. After a long time, especially after high temperature volatilization in summer, it will condense and turn white on the lens surface. This fog will slightly change the original coating color after the lens surface, and the coating color will become lighter after cleaning. However, if the coagulation time is too long, it will corrode the coating, resulting in scratches or large-area peeling of the coating when it is slightly wiped.

3. The coating aging and fogging caused by long-term corrosion of oil and gas cannot be cleaned by any method. This kind of fog is relatively light, and it is more obvious under certain lighting angles.

4. The volatilization of matte paint will lead to fogging. The lens galloping caused by this situation can only be solved by polishing, coating and re-gluing after degumming.

Extended data

Clean the lens

The lens is particularly easy to get dirty, but the dust on the lens cannot be wiped off often. There is a protective film on the surface of the lens, and frequent wiping of the lens will destroy these tissues. If the lens is stained with dust, do not wipe it with towels, paper towels and other items. You can use air to blow the dust off the lens surface through the "leather tiger" (that is, blowing balloons). Blowing with an air balloon sometimes the dust can't be completely blown off. If there is not a lot of dust on the lens, the dust will not affect the image quality.

References:

Baidu encyclopedia-? camera lens

References:

Baidu encyclopedia-camera lens