Camera lens fungus - A guide

• What is lens fungus?
• What does lens fungus look like?
• How does fungus get into a lens? 
• Does lens fungus affect image quality?
• So, how do you clean camera lens fungus? 
• How to clean lens fungus without opening it
• Alternative option one: Sell lenses with fungus 
• Alternative option two: Spend money 

If you use and collect vintage camera lenses, you’ve probably heard of and fear lens fungus. It’s a problem that affects old lenses fairly commonly, and it can drastically affect how the lens performs and how much it is worth. 

What is lens fungus?

A fungus is an organism much like a mushroom. They release spores, and these spores can be thought of in the same way as a plant’s seeds. Once established, they spread out as they grow in search of more food. They absorb their food by secreting digestive enzymes - acids - and these can wreak havoc on a lens’ surface by etching into coatings and elements alike. 

What does lens fungus look like?

Fungus comes in a few varieties. Some are very obviously not a good presence in a lens.If it looks like there’s tendrils, spider’s web, hairs or ‘roots’ on your lens, you’ve almost certainly got a fungus problem on your hands.

Fungus tendrils. Some ‘infections’ look a bit like an overall clouding of the lens.

 Fungus hazing[/caption]Others simply look like flecks of dust - closer inspection under different lights and angles usually reveals a bigger problem - halos surrounding the ‘speck’, hazing, etc.

Fungus spots. And sometimes fungus can look a lot like a patch of mould like you might find on some old bread.

 Fungus patch

How does fungus get into a lens? 

Each case is different, but it’s usually not entirely down to how clean a lens is. Fungus, mould, and bacteria surround us constantly on a microscopic level, and may even have been inside you lens since the day it was made - coming into the assembly room on someone’s jacket, for example. Since these particles are so small, they can easily work their way into a lens assembly over time through the slight bellows action of zooming and focusing a lens, or simply through general use. It’s easy to forget that a lens from 1970 is now nearly 50 years old, and has probably been used hundreds of times in all sorts of conditions. The real issue is how a lens is stored. Fungus loves darkness and moisture, and these sorts of conditions, over time, are perfect for fostering fungal growth. Damp attics, backroom cupboards, tucked away in a shed or garage - these are pretty much the worst places to store old camera lenses. 

Does lens fungus affect image quality?

It depends on the severity and whereabouts of the camera lens fungus infection. You can often get away with using the lens if the infection isn’t all that bad, but it may reduce contrast and can introduce flare in some lights. Severe infections will have the same effect as a very dirty lens - soft areas, low contrast, even outright obstruction of the image. Similarly, if the surface of the lens is physically etched, sharpness will be compromised. It sounds simple but, if in doubt, run a cheap roll of film through a camera using the lens or slap it on a DSLR and see for yourself. Try shooting into the sun to test for flare and against a light surface with the lens fully stopped down to check for any specks.

Fungus spots visible on a bright background[/caption]One thing to remember is that fungus is a living organism so, even if it isn’t affecting image quality now, it may grow enough to affect it in the future. 

So, how do you clean camera lens fungus? 

We approach the topic of camera lens fungus removal with a bit of a warning: Lenses can be really complicated. Many of them were assembled with the use of jigs to hold certain things in place while another piece is attached. They also often require special tools to actually open them up. Depending on where the infection is, you’ll have to go through several stages of complex subassemblies to get to the affected lens element and clean the lens fungus. For example, aperture assemblies are practically witchcraft and about as fragile as a crisp made of cobwebs so we don't recommend trying to take one apart at home - with minimal tools and in a relatively unclean room (we don’t mean offense, it’s just reaaally easy to end up introducing dust into a lens if you’re not careful). 

How to clean lens fungus without opening it

This is a sensible start, but it won’t satisfy you entirely. You can’t ‘clean’ fungus from a lens without physically removing it - but you can prevent it from growing even more.All you need to do is find a windowsill that gets a lot of direct sunlight, and isn’t likely to be disturbed by cats, children or curious visitors. Simply take the front lens caps off your lens but keep the back one on. Open your aperture as wide as it will go and then pop it in the sun for a few weeks.

Keeping the back lens cap on is a basic safety precaution to stop your lens acting like a magnifying glass in the sun and causing a fire. We’ve never heard of it happening and we’re not convinced it’s possible, but there’s no point taking a risk and the effect should still be the same. The UV rays in the sun act as a natural fungicide and should kill off any living organisms on the lens but it’ll take a few weeks.Since the UV rays can’t penetrate into the hidden workings of the lens, this isn’t a silver bullet for a fungus problem and you could end up with further growth in a few years if you don’t store the lens correctly. 

Alternative option one: Sell lenses with fungus 

We’ll happily buy your lenses at Vintage Cash Cow in practically any condition. Fungus, damage, missing pieces - you name it. It’s easy to sell them to us, too. To start, simply request an info pack from us - it includes all you need to know and some Freepost stickers.  Then box up your lenses and anything else you fancy turning into cash and send it on to us. Our expert team will value your items and send you a quote which you can accept and be paid on the same day. You could even put the money towards a new lens!If you don’t like our quote, we’ll send your stuff back free of charge. 

Alternative option two: Spend money 

If you’ve got the lens and you’re itching to use it, we understand that you’ll want to see if you can get it fixed. There’s plenty of lens fungus removal services out there, but one thing to keep in mind is cost versus the price you paid.Vintage lenses can be had for usually pretty decent prices these days. Despite the popularity of analogue photography, most lenses were made in their tens of thousands, so they commonly don’t command that much of a price. Lens fungus cleaning can cost a pretty penny, however, as the process is understandably tricky. These costs can often outweigh the price of a new, fungus-free lens, so it’s worth bearing in mind. So, there you have it. Plenty of lenses have fungus and plenty of them are still usable. Not only that, you can easily get rid of them and make some money towards a replacement. You might get brave and give cleaning a go, and we can only say good luck.  Any tips or experiences with lens fungus? Let us know down in the comments!