Death to Fungus

Tonight, cruising eBay for lenses, as I am wont to do, I came across a Canon 28-135mm IS f/3.5-5.6 USM lens (IS: Image Stabiliser and USM: Ultra-Sonic Motor, ie. quiet auto-focus). I already have the similar 28-105mm USM (no IS) lens, but would love the extra reach and IS would be handy. So far it's sitting on $22.50 with three days to go. Why? In a word - fungus. That's right, there's stuff growing inside the lens. Damn.

But it got me thinking about how I might go about cleaning it up myself (or how much it might cost to get it done professionally and whether that would be worth it - short answer is "probably", but hard to tell sight-unseen). Which got me thinking about the old 70-210mm f/4 I have, which had a bit of an infection itself, and I did a little reading...

This lens came with the EOS 650 that I bought not so long ago as my second film body (after the 3000N). I bought it mostly for the lenses (although I've been using the body too) - the 70-210mm and a 35-105mm and I think they're both out of the original EF lineup. Certainly they have the AF motor noise to prove it! Anyway, the 70-210mm had a little fungus on the inside (where else?) of the front element, and I was suitably terrified of actually opening a lens myself, but the three little Phillips-head were just too tempting. After, I told myself, I don't use this lens much, if at all, and if I kill it dead (which I thought unlikely), I can deal.

So, three screws out and the front element can be removed without too much trouble. I want to go easy on the glass so I try a little alcohol spray and a blower but the fungus won't budge. I try an experimental nudge with my thumbnail (which I keep long for playing guitar) and end up smearing it a little. Ick. OK, so my earlier reading suggested that vinegar (of the white spirit kind, not the apple cider or red wine kind!) was a good tool for this job... and it is. I apply some with a cotton-bud and the fungus basically dissolves. I blot it clean with a lens-cleaning cloth and things look good. This being a push-pull zoom, I can also get to the rear element easily and clean that up too. Make sure everything is dry, put the front element back on and screw it up. Done.

And the result? Well, it looks clean enough although I'll know better when I do some comparison shots against its previous performance. Happily, the lens with the fungus was the easiest one to pull apart, out of my collection. The others look a little more daunting... Meanwhile, I think I'll bid on this 28-135mm and see if I can't somehow clean it up. If I can get it cheap it may even be worth having it professionally cleaned. :)