To check a vintage lens for fungus, shine a small torch through it from both ends at an angle, then inspect against a dark background. Fungus often looks like branching threads, haze looks cloudy, separation can show rainbow-edged patches, and dust is usually scattered specks. Do not dismantle or self-clean before selling.
Key facts before you sell
- Use a torch, not a screwdriver. A light inspection is safe; dismantling risks damage and dust.
- Fungus and haze are different. Fungus often has branching or web-like growth; haze is more cloudy or veiling.
- Separation is an adhesive or cement issue. It can show rainbow edges or crescent patches between elements.
- Minor dust is normal. A few internal specks rarely decide value on their own.
- Fungus spread is debated online. Poor storage conditions matter; isolate suspect lenses and keep equipment dry.
| What you see | Possible cause | What to do |
|---|---|---|
| Branching threads or web marks | Fungus | Photograph clearly and store dry |
| Even cloudy veil | Haze, oil vapour or coating issue | Disclose it; do not wipe inside |
| Rainbow crescent or edge patch | Element separation or balsam failure | Do not heat or dismantle |
| Fine scattered specks | Dust | Usually note it rather than panic |
| Circular wipe marks | Cleaning marks on coating | Photograph against reflected light |
How to do the torch test safely
Remove the lens caps, open the aperture if the lens allows it, and shine a small torch through the lens from the rear and front. Move the light off-axis rather than blasting straight through. Rotate the lens slowly and look through from the opposite side against a dark background.
You are looking for patterns, not perfection. Older lenses almost always show some dust. The important question is whether there is fungus, haze, separation, coating damage, oil on blades or scratches likely to affect value.
What does fungus look like?
Lens fungus often appears as branching threads, fine webs, spots with tendrils or feather-like growth on internal glass surfaces. Sony's support guidance describes fungus as a lens issue associated with storage conditions and advises service attention rather than casual home cleaning.
Do not try to wipe fungus from inside the lens unless you are already a competent repairer. Opening a lens can disturb spacing, introduce dust, mark screws and reduce value more than the fungus itself.
How is haze different from separation?
Haze is a general cloudy or milky veil. It can come from ageing lubricants, coating issues, previous cleaning or environmental exposure. It may reduce contrast, especially in backlit scenes.
Separation is different. Many older lenses use cemented elements. When the cement layer fails, the result can be rainbow-edged crescents, rings or patches between elements. Online sellers often misuse the words fungus, haze and separation, which is why a clear photograph matters.
Does fungus spread to other lenses?
Camera communities debate this fiercely. Spores are common in the environment, and the real risk is poor storage: damp, warmth and darkness. A sensible approach is to isolate obviously affected lenses, keep equipment dry, use breathable storage with silica gel where appropriate, and avoid sealing damp kit in bags.
For selling, do not overstate the risk and do not hide it. Say what you can see, show photographs, and let the buyer decide whether cleaning is economical.
How lens condition affects selling value
Clean optics can carry strong value, especially with Leica, Zeiss, Hasselblad, Nikon, Canon FD and other desirable mounts. Fungus, haze or separation does not always make a lens worthless, but it changes the buyer pool and repair calculation.
Fair Vintage values lenses individually, especially where a collection contains bodies, multiple mounts, filters, hoods and cases. A damaged rare lens may still be worth assessing, while a common lens with heavy fungus may be valued mainly as a parts or repair item.
How to photograph lens faults for a buyer
Use a small torch from the rear element and photograph through the front, then reverse the direction. A dark background behind the lens often makes haze and fungus easier to see. Include one photograph of the aperture blades fully open and one stopped down.
Do not remove retaining rings, clean internal glass or flood the lens with cleaning fluid. A good fault photograph helps value the lens; a failed home cleaning attempt can make a repairable lens into a parts lens.
What people ask online
People often ask whether a lens mark is fungus or separation.
The answer usually needs a torch-lit photo from both sides and a distinction between web growth, haze and cement failure. See an r/AnalogCommunity thread about fungus versus separation.
Some threads debate whether haze is as risky as fungus.
Haze does not spread like a living growth, but it can still reduce value and image contrast. See a Mamiya thread about lens haze.
Buyers ask whether a badly affected lens is worth repairing.
For common lenses repair may exceed value; rare optics can still justify assessment. See an r/AnalogCommunity repair-value discussion.
Selling it without pressure
If a lens has fungus, haze or separation, describe it clearly and send torch-lit photos rather than opening it. Our Carl Zeiss lens, Leica camera and vintage camera and lens pages explain how optical condition affects offers.
Email torch-lit front and rear photos first. Keep affected lenses dry and separate until they are assessed.
Frequently asked questions
Can I clean fungus myself?
Do not dismantle a lens unless you know how to service optics. External glass can be gently cleaned, but internal fungus needs specialist judgement.
Is dust inside a lens a problem?
A few specks are normal in older lenses. Heavy dust, haze, fungus or separation matters more.
Should I store a fungused lens with other lenses?
Keep suspect lenses separate and dry until assessed. The storage conditions are the main practical concern.
Can a lens with fungus still be sold?
Yes, if described honestly. Value depends on the lens, severity, repairability and collector demand.
Sources
- Sony USA, what is lens fungus. Accessed 2026-10-05.
- Nikon manual archive example: compact camera specifications. Accessed 2026-10-05.
- ZEISS photography lens support and service. Accessed 2026-10-05.