Lens Fungus.

I believe my 24-70mm Canon lens has developed lens fungus, which shows up against light areas at F22. A few months ago after walking in the cold to my club i lent the lens and camera for the night to another member to take shots of the portrait night.

Later he came back saying the images were all misty, it turned out it was condensationinside the lens. When i got it home i dried it out slowly at room temperature, today when we checked it has a spiderwork network of threads from the top of the lens, on checking it seems it has fungus a not uncommon problem.

Has anyone encountered this before ? how did you deal with it,and was it expensive to treat ? Any info gratefully received.

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It might not be fungus, it might be just a pattern left on the elements after the water evaporated from getting wet inside and the internal dust.

Spots showing against light areas at f/22 are probably sensor dust and will happen with any lens stopped all the way down. You won't get a bit of fungus to directly show in pictures as it is way out of focus. Bad fungus will cause reduced contrast, haze when shooting into light, increased flare etc. Mild fungus won't show any symptoms.

I've had two lenses that had fungus or a hazy element that as a result made low contrast pictures and were prone to flare. One case was an EF 35-80 that was worth like $30 so I carefully disassembled it and cleaned the affected surfaces. It worked fine after. The other lens was a better lens but badly infected with fungus on almost every lens surface so I took to a local camera and lens repair shop and they cleaned all of the elements. It worked great after, like new.

Thanks Macroimage, your comment is appreciated, ive added a photo taken with the lens and blown up to show the filament like structure. Its inside the lens, not on the outside.

Does it affect images at normal apertures?

Move to Las Vegas

cannylad wrote in post #14661866
Thanks Macroimage, your comment is appreciated, ive added a photo taken with the lens and blown up to show the filament like structure. Its inside the lens, not on the outside.

Wow, that is weird looking. It shouldn't be very expensive to get the lens cleaned. Normally stuff inside the lens doesn't show in the picture sharp like that. I wouldn't leave it too long. Fungus is known to eventually etch the glass or the coating. If that happens, then you might not get a perfect repair although it would still be better.

If you shine a light into the back of the lens, can you see the fungus?

Intresting - That looks like how the aliens spread in war of the worlds.
Open it up and clean with eclipse gently dry and use silla gel or rice if you dont have.

This seems unusual to me. I've never seen such a clear demonstration of fungus in an image taken with the suspect lens, only in images taken of the suspect lens elements. That it is so sharp makes me wonder if in fact the issue is something on your sensor (or rather, the integral filter just above it).

This is easily disproved though. If you don't get the same effect at f/22 with a different lens, it can't be the sensor.

Eight_Blade wrote in post #14662005
Does it affect images at normal apertures?

Not noticable on camera screen, but will show against light skies.

Thanks EP and xarqi, its only on this lens, i would not have the confidence to take apart the lens.


Mister Moose, ta for the advice

i'm not that experienced about mold on camera lenses, but being a certified mold inspector, i've seen many mold samples on glass and that doesn't look like usual growth patterns at all.

i think one of the prior members hit it right, streaks left over from drying.

Mold is tricky, sometimes when you think their should be mold from an occurrence, there won't.

cannylad wrote in post #14663629
Thanks EP and xarqi, its only on this lens,...

OK - if that's the case, it's probably on the rear lens element - try to see it directly, by looking through the unmounted lens at a bright surface.

Thanks Stayhumble, thats an interesting job you have, im going to visit a repair outfit soon to have an estimate, buts its interesting that some think it may not be fungal, it has grown slightly from my first noticed it, which led me to believe its not residue.

regards brian.

Any progress on being able to eyeball it directly?

xarqi wrote in post #14668246
Any progress on being able to eyeball it directly?

Cant see it through the lens, so im guessing its on one of the inner elements, it may be very small, which hopefully is a good sign.

Just like to thank all that have responded, just shows its a friendly and helpfull forum.