Preventing fungus growth in lenses

[brian_keller]

I have some Carl Zeiss and some Nikkor lenses and I was wondering

about fungus growth in them over a period of time. I keep my lenses

in a moderate environment (not a moist environment) - is there

anything else to do to prevent fungus growth (such as use them

often?) over time? Thanks.

[bacsa]

Try to get some silica gel. Put it together with the lenses in a box/bag as airtight as possible. They use this method for transport/storage of coated optical equipment much more expensive than photographic lenses (such as dichroic laser mirrors, nonlinear crystals etc.).

[frank_miles1]

My wife and I lived in Abu Dhabi, UAE for three years. Being on the Arabian Gulf, we had our share of humidity during the summer. The air conditioner in our apartment was very good at cooling the place, but less effective at drying the air. As a result, one day my wife noticed a white powder on her camera strap and case. On looking closer, there were spots of mould or fungus inside one of my lenses.

 

The exteriors cleaned up nicely with a vinegar solution. In doing my research, I read in one of Robert Monaghan's web pages that some people swear by UV to kill off mould/fungus inside lenses. I aimed the affected lens at the sun for a few days and never saw it progress any more.

 

We also shopped around and found a dehumifier, realizing we had a moisture problem in our place.

 

The lenses were also exposed to moisture when you took them from a mildly air conditioned environment to a high humidity evening or morning. If we were going to im these situations, we tried to leave the cameras in a hot location.

 

Hope this helps.

 

Frank

[nick_wilson2]

Storage seems to be the problem, as it seems to be humidity and dark. I get the impression that it is not a real problem in many parts of the world (cool? dry?).

 

I am intrigued by the 'sun solution' and have recently tried to keep some lenses in the light as a preventative, but am wary. I wonder how much UV gets through the glass.

 

There are humidity controlled cabinets available (but maybe not where you are?), or some people make their own with a low wattage bulb.

 

Probably the easiest, though, is airtight containers with indicator silica gel, as posted above. I would recommend NOT using the small sachets, but get some in bulk from a chemical supply place, if you have enough lenses (share some with a friend if too much!). It can be put into muslin-type bags that breathe.

 

It is easily regenerated in a frying pan on the stove, when the colour is lost (better than the oven, IMO).

 

There is orange indicator gel now, as the cobalt chloride for the bright blue stuff is apparently toxic.

[andy m.]

I too am very interested in this issue.

 

Some simple precautions might include not keeping them in a bedroom (high humididty is likely to result from exhalation during the night). Or, if there is no alternative, keep them in a box or preferably a safe and include fresh silica gel.

 

I seriously doubt that U.V. will significantly penetrate a coated glass lens. In my opinion, once there are traces of fungi on the glass that can be seen by the naked eye, these should be killed and cleaned off by a technician. Leaving them in place is not the best option.

[david_altmann]

i have some bags of silicagel but i dont use them because someone told me they are toxic. if that is true, is there a save way to use silicagel ? or is there another product ?

 

regards, David

[bacsa]

as I said, those bags are commonly used by big and important companies delivering expensive equipment. The safety rules here request that bottles with simple ethanol are locked up in a cupboard. So silica gel bags have to be less toxic than a bottle of whiskey:o) Of course, you should not eat them.

[Julio Fernandez]

Silica gel is not toxic by itself, it is a chemically inert colorless material.

 

However they add a little cobalt chloride to it to signal humidity changes. The cobalt choride forms different hydrates according to the humidity in the silica gel; those hydrates have different colors, rose when "wet", blue when "dry". When the silica gel gets rosy it is time to heat it to dissicate it again; it will turn blue.

 

The cobalt chloride is toxic but only if you eat it. I think that silica gel with cobalt chloride (the "standard" blue/rose type) is perfectly safe for normal use in keeping things dry when humidity is not very high, it would be standard recommendation for your situation.

 

When things get really humid you might also try calcium chloride as a dissicant. This salt and its solutions absorbs humidity like crazy. You just put a few grams of calcium chloride in an open small bowl in a closed space (I mean REALLY closed, airtight). It will absorb all the water in the air, and a liquid will quickly replace the crystals. The liquid is still a powerful dissicant. CHECK IT OFTEN because as it absorbs the water in the air, the liquid increases in volume, and will overflow if let alone too long!. When diluted, you just replace it. It is less toxic than cobalt chloride. Wash your hands with a lot of water if you touch the liquid or the crystals, it is not dangerous but it is nasty.

 

Do not use calcium chloride to dry air in an open container because it will overflow in just a few hours if humidity is high enough

 

If you get fungus in a lens take it immediatly to a good photo repair shop, they will clean it in most cases. Do not let the fungus too long because it will "mark" the lens coating or in severe cases the glass itself.