Avoiding Fungus Damage to Lenses and Camera Optics
IMPORTANT: DO NOT SEND FUNGUS DAMAGED LENSES TO CINEMATECHNIC. It is nearly impossible to repair lenses that have been damaged by fungus. We cannot accept lenses for repair that have fungus present inside the lens. The main reason for this is that the fungus will emit spores the minute the lens is dissasembled, and this will contaminate our workshop, possibly destroying other customers lenses as well as our own optics and test equipment. Carl Zeiss has a similar policy.
Fungus usually damages the lens element making repairs impossible because the glass surface has been etched by the acid emitted by the fungus. Even if the lens is completely disassembled and cleaned, and new lens elements are installed, we cannot guarantee that the fungus will not return.
TO AVOID FUNGUS DAMAGE:
Do not store your lenses in any environment with humidity over 65%, or temperatures over 86º F (30º C). In humid environments, a garage or the cargo box of a truck is a dangerous place to store lenses overnight.
If you must use your lenses in an envirorment that exceed the limits stated above for temperature and humidity, you must allow the lenses to dry out. This can be accomplished by leaving the lenses out in an air conditioned room overnight. Do not leave the lenses in their case.
If you believe you are working in a situation that has a high risk of fungus damage to your lenses, you should expose the lenses to direct sunlight. Place the lenses on a flat surface with front lens cap off and the front element exposed, and iris wide open. Later you can reverse the lenses so they sit on their front elements and expose them to sunlight through the rear element. Do not do this inside a car or another enclosed space where the temperature may exceed 120º F. This can damage the lubricants and adhesives used in the lens construction and require a complete overhaul.
In a worst case scenario, exposure to a strong emission of X-rays can kill fungus. This can be accomplished by exposing the lenses to the output of an X-ray device, set to a high exposure. This can only be done by trained professionals and you must not be anywhere near the lenses during exposure and all personnel present must be protected behind radiation shielding. Once the exposure is performed the lenses will not retain any residual radioactivity from the X-rays, but the exposure should kill any live fungus or spores.