Lens Fungus – causes and how to prevent it from happening to you!


I hope you’re all locked down and ready for the upcoming weeks in isolation!

My name is Andrew Morgan, I’m an ambassador for Sigma South Africa and have been a full time professional photographer for about ten years.

Although I now live in Cape Town, I spent the larger part of my photographic career living on the island of Zanzibar in the Indian Ocean, a tropical paradise for holiday makers, but full of a wide range of difficulties as a photographer.

One of the worst things to plague me during my time there, was having to deal with fungus growing in expensive camera lenses. Fungus is caused by small dust particles carrying fungal spores getting in between your lens elements where they then come to life with the help of moisture in your lenses.

There are a lot of conditions that lead to this happening, in places like Zanzibar or Durban for that matter, a general very high humidity due to the tropical climate is the greatest threat, but anything from shooting in the rain and not drying your gear properly or even the raised humidity during the rainy months can cause fungus to occur as well as storing your gear badly.

So fungus and mould are caused by moisture getting into your lens, they thrive in a relative humidity of 60% and over. The ideal humidity to store camera and electronic equipment is between 35 and 45%. There are a number of ways of preventing or at least trying to prevent the growth of fungus, in my experience the absolute best way is to get a specialised dehumidifier dry cabinet. I looked for them all over the world and I don’t believe you can buy them in South Africa. I bought mine from B&H Photo in New York and had it shipped. You can get them in various sizes depending on how much gear you have, but they are the ultimate solution as you can set the humidity to what you’d like it to be.

As these aren’t readily available there are some other ways that may be more practical to protect your lenses, it is particularly worth thinking about now while most of us won’t be using our gear as much as usual. Gear sitting in a dark cupboard or packed away in a camera bag for long periods (a week or more) can be susceptible to mould and fungus.

If you have air conditioning in your house, storing you equipment in an air conditioned room is a great idea as air conditioners dry out the air. Fungus also doesn’t like light, so although it’s not safe to leave your equipment in direct sunlight, putting them inside a clear box that allows light in rather than a dark camera bag or cupboard can be a good solution. Everyone knows about silica gel packs that you get inside medicine bottles and when you purchase new electronics, these are great, however it isn’t really enough to just have one or two floating around in your camera bag, but you can buy silica gel in large quantities that you can then put into a clear box perhaps in something like a sock or even a cup. Silica desiccant doesn’t last forever though, some of them can be revitalised by drying them out in a low oven or in a microwave, but it’s good to just get a new batch of it from time to time.

A company called BRNO came up with a really nice little gadget, they have these lens and camera body caps that take a small silica gel pack inside. You can see by the colour of the pack whether it needs to be replaced or not. These are great and well worth getting a few as an extra layer of protection.

View example here:

You can also get things like a small rechargeable de-humidifier, I’ve not tried these personally, but they seem a good solution to put in a clear box with your gear. You can find some options over at solencosa.co.za

And for an even easier, practical and affordable solution and one I have used, is to go and get a few cupboard moisture absorbers, they sell them at places like Builders Warehouse and even certain supermarkets. An Air Scent moisture absorber sells for about R24 at Game. They have a desiccant and a separate compartment for the water that it collects, so you can actually see how well it works.

So in this time when you may find you aren’t using your gear too often, take it out of however you choose to store it at least once a week. Make sure your gear is cleaned properly and look out for any signs of mould or fungus growing. If you catch it early, especially if it’s on the outside elements, you can just wipe if off before it eats into the lens coatings.
Once you get fungus on the internal elements, the only way to get rid of it is to have someone open up the lens and if it isn’t too bad, clean it off the elements or if it’s eaten into the coating, the affected elements will need to be replaced. Personally I am still able to use some lenses with fungus in them when shooting at wide apertures as you don’t notice it, but as soon as you’re trying to shoot at f8 etc, it will be noticeable.

Lens fungus is not biased to any brand, I have either personally or seen friends with weather sealed lenses from all of the brands end up with fungus in their lenses eventually. Take care, be aware and maybe you can save your gear!

Stay safe and wash your hands!
Andrew Morgan