Is it acceptable for second-hand lenses to be slightly gray?

Slight gray will not have a significant impact on image quality, especially in the case of daily use. Micro-ash is composed of tiny dust particles inside the lens, and its influence on imaging will only appear under certain conditions. When buying second-hand lenses, you can refer to the gray situation to judge the service life, use degree and preservation of the lenses. Slight gray does not necessarily represent the quality problem of the lens. For most photographers, a slight gray color is acceptable.