Canon EF 28-105mm f/3.5-4.5 II USM Lens with Fungus
My one time most used lens grew lots of fungus when I moved to Phnom Penh 5 years ago and I thought opps that one is ruined. Left it sitting, unused for nearly 4 years. The fungus was even thicker by this time. Was thinking of having it stripped and cleaned but did a little trawl of the internet to see if anyone with a similar problem could say if it was worth saving.
Found a couple of sites that suggested putting the lens out in strong sunlight, which we have plenty of here in Cambodia, with open aperture and place on a siver reflective surface (tin foil). I tried it, nothing ventured nothing gained, and beggar me if it didn’t work. The filaments of fungus almost disappeared with an hour. There was a little damage to the front element where the fungus has damaged the coating but nothing major that might have caused problems.
So I took it out on the front of a 40D and the results quite surprised me, the images were sharp and contrasty after a tiny tweek in LR.
I really would have thought with the level of damage to the front element the lens would have been useless but it was far from it and is now back in my bag.