Everything to Know About Camera Lens Fungus
Bad news, mushrooms are growing in the lens. This can also be seen in prisms, viewfinders, digital sensor filters, and other optics.
Lens fungus is the mycelium from fungal growth. There are multiple types of fungus that can grow.
The optimal conditions for fungal growth are a temperature range of 10C to 35C, relative humidity of 70% or higher, and darkness. For instance a damp camera bag or basement during a period of heavy rain.
To prevent fungal growth:
- 30% to 60% relative humidity.
- 40C temperature.
- Light and ventilation.
- Lenses and gear should be clean and dry.
There are DIY and commercially available dry boxes and cabinets designed to store camera gear. These are useful for environments that are good for fungal growth, such as tropical climates.
Minor lens fungus might not be noticeable in images. The further towards the front of the lens, the less noticeable fungus will be.
Larger amounts of fungus will reduce contrast and sharpness. If the fungal growth is bad enough, parts of the image can be blocked.
This would be a great lens for the Minolta X-700, if not for all the fungus on the rear lens element.
I was looking forward to comparing the Vivitar 90mm f/2.5 macro to the Vivitar 90mm f/2.8 macro lens. Unfortunately, the copy I got my hands on was not stored properly.
Electronic dry boxes have, surprise surprise, electronically controlled humidity. They will often have a digital hygrometer to monitor and display the humidity level.
These dry boxes are easy DIY solutions as all that is needed is an airtight box and dessicant, such as silica gel. For travel, a bag and desiccant can be used.
Desiccant will get saturated with water over time. It does not need to be replaced. The moisture can be removed by sticking silica gel in an oven at 120°C (248°F) for 1-2 hours.
Cleaning and removing fungus from a lens requires disassembly. There is also no guarantee removal will fix the problem as the fungus can etch glass.
It can be difficult to find someone willing to clean lens fungus. The most often situation is where the cost of repair is more than the cost of replacement.
The outer front and rear elements of lenses can be surprisingly easy to remove. Often only lock rings and possibly a few screws hold them in place.
The closer the fungus is to the aperture, the more difficult it will be to remove. The more technology and newer a lens is, the more difficult it will be.
I’m not going to provide a tutorial on how to disassemble lenses. Here is a list of stuff that I used on the few occasions where I removed fungus from a lens.
- JIS Screwdrivers
- Lens Spanner
- Rubber Retainer Ring “Wrenches”
- Lint Free Tissues
- Nitrile Gloves
- Naphtha (lighter fluid)
Naphtha is very flammable and highly volatile. It needs active ventilation and the use of protective gear such as gloves. It is a powerful solvent that does an excellent job of removing fungus from glass lens elements.
Balsam separation is where the bond between lens elements begins to delaminate. Historically Canada balsam was used, but now epoxies are used.
Lens haze is where the optical clarity of a camera lens is blocked with minute particles, often dust, or moisture. This can result in photos with reduced contrast, a foggy or milky appearance in images, or a general lack of sharpness.
Mild haze may not noticeably affect image quality, where as severe haze can render a lens practically unusable.
A common cause is exposure to hot temperatures, like being left in a sunny car during summer. The high temperatures can allow liquids such as lubricants vaporize, which get deposited on lens elements when the temperature drops.