Fungus problem on SMC 75-150. Advice please.

Hi folks,

I picked up an SMC M 75-150 f4 zoom a few weeks back for £11 on E Bay. I've only just had a good work out with it for the first time today. It takes really sharp photos which I'm really happy with but I can detect some limited evidence of fungal growth in the lens which I'd missed when the lens first arrived. I am aware that the only way to get rid of it is to strip it down which I won't be doing in a hurry! Also, I understand it will get worse over time.

My question: if I continue to use it, is there any chance I could contaminate the camera body or can I continue to use it?

Any comments would be much appreciated.

Dave

Dave

I have used this chap a few times to have M lenses repaired. I can recommend him.

http://www.cam-rep.co.uk/

Hefty I believe came with the solution to put it into the sun since the UV radiation would kill the fungus.
Don't really know how effective that is but try it I would say you have nothing to lose

I have also used him on a few occasions, once to clear fungus off a M series 50mm f4 macro and the lens came back in excellent condition.

Cam Re's website suggests a charge of possibly £52 to remove fungus. Thanks for the recommendation guys.

What of my original question? Is it possible to continue to use the lens without contaminating the camera body?

Dave

Yes.

The fungal spores are already inside your camera body, they're inside every lens you own and they're part of the air you breathe day-in and day-out.

Under normal circumstances they will remain dormant and invisible, they'll only cause damage under specific conditions (warm, dark, damp as a rule). What you see on the lens isn't the fungus itself, rather the trail left behind by it.

The fungus eats the nutrients inside your lens (hence it's more prevalent in older lenses where he elements are stuck together with Canada Balsam rather than today's synthetic adhesives which most fungi find unpalatable), it then secretes an acid as it moves along the lens surface. The acid chemically etches the coatings on the lens and it is this that makes up the "spider's web" that you can actually see.

You can kill fungus with prolonged exposure to UV light but it's hard to know whether the job's been effective or not. If the "web" isn't growing over a period of time it's pretty safe to assume the fungus is dormant so I'd only bother with cleaning if it made an appreciable effect on image quality.

To stop further outbreaks you just need to make sure your lenses are kept dry, cool and ventilated when they're not in use.

Hefty,

Thanks for that brilliant exposition! That certainly makes things a lot clearer. I really like the 75-150 lens - especially for £11 so it's great to know I can carry on using it.

Dave