how long does it take fungus to grow on lens?

[chij]

i bought an old 35mm rangefinder on ebay
advertised as clean, fully tested, resealed with a pristine lens

7 weeks later i'm checking out my equipment late one night for kicks (i know i'm not the only one who does that) and notice fungus. it covers about 0.5cm in length from the edge of the lens to the center, and spans about a fifth of the circumference of the lens

could it have grown in the 7 weeks since seller shipped it as he claims

kept it in my dry bedroom
shot one roll outside when it was dry and cold (early spring)

 

[chioque]

Where I'm from (hot >28C, and humid >80% climate all year round), fungus can definitely grow within that time frame, if the lens is not kept in a humidity-controlled dry cabinet

 

[Grytpype]

I'd guess it could grow that quickly in ideal conditions (like Kuala Lumpur!) but I would reckon it would have to be already established in the lens. In less humid conditions, fungus growth would be more likely to take years.

 

[Jim Noel]

Fungus growth is dependent on light intensity, relative humidity and temperature. Control of these three factors can inhibit the growth.

 

[Sirius Glass]

Faster than you want.

If a camera is sitting around, take off the lens cap, open the aperture and set it in a position so that the lens gets sunlight in it. Then leave it there until it is time to use it again.

Steve

 

[Ian Grant]

Only took a month to lose some cameras and lenses stored inappropriately in the UK one Summer. A cool poorly ventilated darkroom can suffer as you get condensation from warmer air from outside. I don't store lenses (or cameras) in an unheated or basement darkroom.

Ian