How to remove fungus from a camera lens (and how to stop it in the monsoon)

Lens fungus grows fast in India's humid monsoon and can damage the glass for good. Learn how to spot it, what you can safely clean yourself, and how to keep your lenses dry.

Shine a torch through the lens. Fine web-like threads or spots inside mean fungus. You can only clean the outer glass yourself, using a blower, then lens cleaner on a soft cloth. Fungus inside the lens needs a brand service centre. To stop it, store gear in a dry, ventilated place or a dry box with silica gel, and use it often.

• 1. Do the torch test: Remove both caps, then shine a torch through the back of the lens while you look in from the front, and the other way round. Fungus looks like thin branching threads, tiny cobwebs or fuzzy spots, often near the edges of the glass.
• 2. Work out where the fungus is: If the marks come off when you wipe the front or rear glass, they are on the surface. If they stay put and look like they sit between the glass elements, the fungus is inside the lens.
• 3. Blow off dust first: Use a rubber blower to remove dust and grit from the front and rear glass. Wiping before blowing can drag grit across the coating and scratch it.
• 4. Clean the outer glass gently: Wet a lens tissue or soft microfiber cloth with just a little lens cleaning fluid. The fluid always goes on the cloth, not on the glass. Begin in the middle of the lens and work out to the edge using small, light circular strokes. Skip household glass cleaner and diluted alcohol: they can harm the coating.
• 5. Send inside fungus to a service centre: Fungus between the elements can only be removed by opening the lens. Take it to an authorised Canon, Nikon or Sony service centre so a technician can check whether it can be cleaned.
• 6. Dry the lens before you store it: After shooting in rain or humid weather, wipe the lens and leave it out in a dry, airy room for a few hours. Packing it away damp traps moist air inside.
• 7. Store it in a dry box with silica gel: Keep lenses and cameras in an airtight box with fresh silica gel, or in an electronic dry cabinet. Aim for around 40 to 50% humidity. Nikon advises against places that are poorly ventilated or over 60% humidity.
• 8. Use your gear and give it light and air: Take the camera out and shoot regularly, especially in the monsoon. Fungus likes dark, still, damp spaces, so moving air and daylight help. Avoid keeping gear zipped in a bag for weeks.