Lenses containing moisture & fungus

Moisture and fungus are two of the most common environmental issues that affect camera lenses. While both start subtly, they can progress over time and may reduce the quality or usability of equipment. Understanding what they are, how they develop, and their potential impact will help you better care for your gear.

Moisture in lenses occurs when water condenses on the glass, often from temperature changes or poor storage conditions. It can appear as droplets or a fine haze, usually forming a consistent pattern rather than random specks like dust. While moisture alone rarely affects images directly, it creates an environment for fungus to grow if left untreated.

Fungus develops when trapped moisture combines with warmth and organic material inside a lens. It may begin as small spores with faint halos, then spread into larger, thread-like patches across the glass. In early stages, fungus has little impact on images, but as it advances it can etch into coatings and glass, reducing sharpness, contrast, and overall image quality.

MPB carefully evaluates the severity of both moisture and fungus when grading equipment. Minor signs that do not affect image quality may be accepted and reflected in the price/quote, while advanced cases that impact usability or risk long-term damage are graded lower or not accepted for resale. This ensures transparency and fair value for buyers and sellers.

1. Light moisture:

Light moisture consists of a fine mist or a small patch of sparsely spread droplets. This level of moisture does not affect images taken using the lens, but does represent minor potential for the moisture to get worse due to it forming the beginnings of an ideal environment for fungus growth.

2. Heavy moisture:

Heavy moisture is a natural progression from light moisture, consisting of larger moisture droplets and/or denser spreads that can cover an entire element. The heavy moisture level presents greater potential for fungus to grow, perhaps with signs the process has already begun.

3. Minor fungus:

Minor fungus is the level at which fungus has begun to grow, either from patches of moisture or of its own accord. These small patches of fungus could exhibit minor threads beginning to spread, or they could be small circles of translucent white. They will not affect images, but represent a moderate risk of the fungus getting worse with ideal conditions.

4. Moderate fungus

Moderate fungus sits at the more severe end of the fungus scale. Fungus in this category will exhibit lots of threads, and lens elements could contain multiple small patches of fungus. The key with this level of fungus is that the lens still has use, fungus hasn’t taken over the lens and will likely not affect images.

5. Fungus

The highest level of fungus is reserved for items that we cannot purchase due to the severity of the fungus within. This level consists of fungus that has taken hold of the lens, likely spreading across entire glass elements. Fungus here may affect images, and will likely be very obvious when looking through the lens.

Some tips from our in-house Product Specialists on checking your items to determine the levels of moisture or fungus: