For the seller

Fungus, haze and dust: reading an old lens

The glass of an old lens, up close

Hold an old lens up to a bright window and look through it from the back: what you see is either dust, haze or fungus, and the three mean very different things. Dust is harmless. Haze is a film on the glass that softens every photograph. Fungus is alive, grows in the dark, and can etch the glass for good. Telling them apart takes one minute and no tools.

The one-minute check

Point the lens at a bright light or the sky, look through it from the rear, and tilt it. Open the aperture first if there is a ring for it, and use a phone torch shone through at an angle for a harder look.

  • Dust: dark specks that sit still and look like what they are. Every old lens has some. It changes photographs not at all, and it is not worth anyone opening a lens for.
  • Haze: an even, milky veil, often only visible with the torch. It can be oil mist from the aperture, outgassing, or the early stage of worse. Haze lowers contrast and gives photographs a glow; sometimes that glow is even wanted. It matters, and it needs saying when you sell.
  • Fungus: threads, spider-web patterns or branching spots, usually starting at the edge of an element. This is the one with a clock on it.

What fungus actually is

Fungal spores are everywhere; they germinate when a lens sits in the dark, in humidity, with something to eat — the grease, the coating, the dust itself. That is why lenses from damp cupboards and leather cases grow it and lenses that were used do not: daylight, especially UV, keeps it down, and use keeps air moving. Early fungus can often be cleaned by a technician; long-established fungus etches the coating and sometimes the glass, and then no cleaning brings the lens back.

What it means for the lens

A little fungus at the edge often changes photographs less than people fear, and lenses with it are bought and sold every day, honestly described. What it does change is the conversation: it must be named, it spreads if storage stays bad, and on some lenses the cure costs more than the lens. Our guide to what old lenses are worth looking at for covers the rest of the picture.

What not to do

  • Do not open the lens. More lenses are ruined by amateur cleaning than by the fungus itself: scratched coatings, lost shims, elements refitted the wrong way round.
  • Do not wipe the inner surfaces through the mount, and do not use household cleaners on any surface.
  • Do not seal it in a plastic bag, which keeps the humidity in. Store it dry, with airflow, and give it daylight; a windowsill out of direct sun does more good than a cupboard.
  • Do not park it back in the leather case, which is exactly the microclimate it grew in.

If it is a whole shelf of glass

In every camera collection some lenses are clear, some hazed, one or two grow the garden. That mix is normal, and it is not a reason to clean, fix or discard anything before passing the collection on. We buy collections whole, fungus included, and judge them looking through the glass, not at the word. Say what you see, in your own words; the form below asks exactly that.

Short answers

How do I know if my lens has fungus?

Threads or branching spots, seen against a bright light through the rear of the lens. Even haze is haze; still specks are dust.

Does lens fungus spread to other lenses?

Spores are everywhere anyway; what spreads is the conditions. Keep storage dry and lit and the rest of the shelf is at no special risk.

Should I have a lens cleaned before selling it?

No. Describe it honestly and leave the decision to whoever takes it on; a cleaning attempt gone wrong is worse than any fungus.

Why we keep the story

A collection is not a pile of objects.

It is years of somebody deciding what was worth keeping, and sold off piece by piece that is the first thing to go. So before anything is sold, we sit down with you and record it: how it started, what the best of it was, the piece that got away. That story stays on every object with the collector's name, and goes with it to whoever keeps it next. You get a page where you can see where each piece ended up.

Three ways the story gets recorded

On camera, where it lives. We travel to the collection and film it properly: you talking about how it started, the room and the shelves as they are, the objects in your hands. Wherever in the world the collection happens to be.

On a call. If the collection is sent to us rather than collected, we have the same conversation over a video call and write it up, with one photograph of the shelf as it stood.

In writing. If you would rather not talk at all, answer a handful of questions in your own time and in your own words. It goes on the objects exactly as you wrote it.

It never changes anything else, and you can always say no to it. Some conversations run ten minutes, some an afternoon. Read the collections we have taken on

If it is a whole collection

We buy whole collections, not single pieces: one person takes all of it, and the story is kept with every object. Tell us what you have and a person replies within two days.

How passing it on works, in full

1The collection
What is in it
Pick everything that applies. Something else opens a line to tell us.
Roughly how many pieces
A guess is fine. Nobody has counted.
How would you describe it
There is no wrong answer here, and a lot of ordinary is a normal collection.
One or two sentences. This is the question we care about most.
2Where it is, and how it could reach us
Town and country is enough.
How could it reach us
Unseend is in Rotterdam, the Netherlands. Sending and bringing are as welcome as a visit; if it is sent, we pay the freight and insure it.
When does it need to be gone
No hurry is a good answer. It lets us plan a visit properly.
3Condition and photographs
In your own words. Broken, incomplete or untested is fine and is normal; it only needs saying.
Photographs
Three to ten photographs The room and the shelves as they stand. Phone photographs are fine, and a slow walk round on video says more than any of them.Send them to hello@unseend.com
Or attach them to the reply that comes back within two days. Any of them works, and nothing is looked at until a person reads it. Do not clean up first — the shelves as they stand tell us more than a tidy arrangement.
4The number, and the story
A number or a range, whatever you have in mind. You will get an honest answer either way.
Would you tell the story of it
Filmed at the collection wherever it is, on a video call, or written in your own time. It never changes the price.
5How to reach you
The reply comes here, from a person, within two days.
Only if you would rather be called.

Answered within two days, by the person who would come, and by email at every step after that. Nothing you send is shared with anyone, and your photographs are deleted if we do not go ahead.

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