Lens Fungus : What And Why

Now lens fungus is something which really freaks me out. Recently a friend called me asking the same as her Canon L series lens started developing tiny patches of fungus. Now on her request, I’ve specifically made this post for anyone who’s dealing with the same issue. And the chances are if you live in the Indian Subcontinent, you will surely deal with it at least once.

Via David Neal
Via David Neal

Primarily, the fungus is this white web which grows onto the glass elements of the lens. Does it damage the lens physically? Well only in certain extreme conditions but initially it will just lead to deterioration of image quality. So you’ll start noticing soft results, light spills and loss of clarity almost immediately with fungus in your lens. A simple way to identify if you do have fungus is to look up the lens against light. Just shine a torch through and you’ll be able to see it pretty easily.

In case you do notice any, here is what to do and why :

Light fungus is quite easy to remove and it bringing the lens to its original condition would not be an issue. If you’re unable to take the lens immediately to a service station then just open the lens caps up and put the lens under sunlight for a few days. Now this would have to be done for a long time so instead you can also put it under a UV lamp for 14 ~ 16 hours for a few days. This should stop  the growth of fungus or hold it back, giving you enough time to take it to a service station. For more dense fungus, I’d recommend just taking it immediately to a service station. Its important to understand that sunlight / UV is not a solution for fungus. It would kill the already growing fungus but it doesn’t do anything to the inactive spores.

The only real solution is to take it to a service personal. I don’t recommend the DIY way (hydrogen peroxide blend with ammonia, as is a vinegar and water solution) because even if a little fungus remains, it will grow back.

This brings us to the worst case scenario. If the fungus remains on the lens long enough, it will eat into the multi layer coating of the lens which protects it from flares, color fringing, reflections etc. Now there are a few professionals who do re-coat lenses but I don’t think they deal with consumer grade lenses, mostly only Leica, Hasselblad or Large Format Cameras. I will not even talk about the expenses for the same (its a little too much).

Protection Tips :

A dry cabinet is much like a fridge. But whats different is that it controls the humidity along with the temperature.
A dry cabinet is much like a fridge. But whats different is that it controls the humidity along with the temperature.

Prevention is better than cure so lets just stick to that. Don’t keep your cameras in the camera bag (specially with padding) as the foam inside holds moisture, encouraging fungus growth. After a shoot, its best recommended that you clean your camera, dry it (best done in front of a Air Conditioner on DRY mode) and then store it in airtight zip locks or containers. Someone once recommended using a hair dryer to remove moisture but I would never recommend that, nor would any other professional (hair dryers sudden burst of heat will dry the element but won’t remove the room moisture, so its best to just use a AC. Also the Dryer’s focused head causes unbalanced heating, not a good thing for the lens).

Initially I would use silica gel with the ziplocks to store the lenses but its not a long term option. Silica gel would get saturated with moisture sooner or later as you open and close the bag / container. The best option is to either buy a dry cabinet (Kalabhai supplies for India from Singapore) or get a Pelican. They will make sure that there is no moisture damage to the lenses ever.


2 thoughts on “Lens Fungus : What And Why

  1. It’s only time when these lens maker make anti-fugus/ mold/ dust/scratch lenses… These days the technology is very advanced so I believe this is not very far…

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