Canon 50 1.2 with fungus

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snapper78

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Hello

First let me say how pleased I am to have found this forum with so many knowledgeable and helpful members.

I have a Canon 50 1.2 which I have owned for many years and which used to take nice pictures but now has acquired a nasty fungus infection. Can anything be done about this or is it a terminal illness?

Mechanically and cosmetically it's still pretty good, although I seem to have lost the front cap.
 
It all depends on how long the fungus has been growing, if it has done any permanent damage to the lens. Sometimes it's just a matter of opening it up, and cleaning with lens fluid. Other times, more potent elixirs must be used.

I'd think the 1.2 would be similar in construction to the 1.8, and not a problem to do-it-yourself if you have the rudimentary tools and skill set for such things. If not, then send it off for a good cleaning. If it's not etched too bad by the fungus you should be able to take many wonderful photos with it.

PF
 
Can you tell where the fungus is? In front of or behind the aperture blades? The Canon 50/1.2 is remarkably easy to take apart, especially the rear element groups. If you're up to it, you can try to clean the lens yourself. Or you can send it out to a qualified repair tech.

Jim B.
 
I think the fungus is in the rear element. The front looks OK.

I have thought of selling it on eBay but definitely not as mint. ;) I think I'd rather take the chance on taking it apart if it's really easy to do. I've taken a few FSU lenses apart but they're a different kettle of fish since if it all goes wrong one can always find another for a small sum. Still, in its present condition the Canon lens can't be very valuable - or can it?
 
snapper78 said:
I think the fungus is in the rear element. The front looks OK.

I have thought of selling it on eBay but definitely not as mint. ;) I think I'd rather take the chance on taking it apart if it's really easy to do. I've taken a few FSU lenses apart but they're a different kettle of fish since if it all goes wrong one can always find another for a small sum. Still, in its present condition the Canon lens can't be very valuable - or can it?
Click to expand...

This is a high dollar lens..

Take digital images as you go along and take notes on how you disassembled each part.. Then go back together in reverse..
 
snapper78 said:
Thanks for that link. It looks very useful. It looks as though I need to get one of those spanners.
Click to expand...

Fortunately the spanners can be had cheaply on eBay

http://www.ebay.com/sch/i.html?_trk...r&_nkw=lens+spanner+wrench&_sacat=0&_from=R40

If you are not inclined to send away for one from eBay you can easily make one out of a machinists divider (also known as calipers) by grinding the points down into chisel points like those on a screw driver - this is useful to know as machinists dividers can be found in hardware stores. (also on ebay)

http://www.ebay.com/itm/LUFKIN-4-0U...554?pt=LH_DefaultDomain_0&hash=item565bf1b0d2
 
You can also get to the fungus by removing the front element group. If you look around the front edge of the lens you'll find a small set screw. Back out this screw, and then firmly twist the front of the lens, it should thread out. I don't recommend getting into the back of the lens, the glass is very close to the spanner slots, and I have seen more than one of these lenses ruined by a slipped spanner.
 
I've only dealt with a couple of lenses with fungus, but I've had surprisingly good results with simple moisturizing hand cream, applied generously and left on for about five minutes, then gently removed with a q-tip. Obviously, this will not remedy coating damage, but it has proven very effective in removing the fungus without undue effort and additional damage to the lens.
 
I had two of these with fungus damage. The damage in both cases was on the surface immediately behind the aperture iris. The lens element damaged is a cemented pair. The damage appeared to be etched into the glass. Several people told me that the fungus secreted an acid that eats into the glass. Certainly it looked like that. I sent that element to several shops, including Essex who had a go at polishing it but just put scratches on the glass. Focal Point (John van Stelten) advised that with a cemented pair it is necessary to separate the elements first before attempting to polish and recoat the surface, but that is risky and might fracture a lens element.

I eventually sold both my copies on, with full disclosure and return privilege, for a fraction of the price I'd paid. I'll never buy another lens without a personal inspection and return privilege.
 
I bought a 1.8 Serenar and it had a 'lumpy' front on the rear cluster. I quickly had it out from the back but decided to go the gentle polish way, and it worked fine. Lucky! :)

That lens is better than the Summitar 2.0 and its weight is the only 50mm that will balance the Bessar I to a level position.

Try solvents carefully first up (all the way thru to Xylene which is to be used sparingly only!) then try a fine polish if that fails. I read that Canon use the hand cream trick at the factory so don't write that one off as urban myth.

It''s a dandy lens, you'll find.

Good luck.
 
Thanks everybody. I need to find a screwdriver small enough to fit in the tiny screw on the front and probably a spanner if I need to get the back off. I sent an enquiry to a Canon authorized repairer in London but they quoted me £100 as a first estimate so the DIY option seems a better bet, with selling on eBay as a fall-back option. It is perhaps the most beautiful and exotic lens I possess but I have a bunch of nice FSU lenses, including two J3s, a Canon 50mm F 1.8, Leitz lenses, Summitar, Summarit and Elmar 90mm F4, and probably the jewel in the crown, a Nikkor 85mm F2 in LTM so, photographically speaking it is not indispensable. Actually I'm more of a gear freak than a real photographer, although keen on photograpy since the age of ten in 1945. The eye is somewhat lacking. The FSU stuff is mostly recent and due to the discovery of eBay, which can be addictive. Generally I find that the FSU lenses are good but the cameras often less so.
 
A progress report: I got the spanner (from Singapore) and a new set of small screwdrivers locally. So far have managed to get the rear off and have cleaned up the glass using hand cream. It looks very promising. I also tentatively cleaned the diaphragm but decided not to do too much because it appears to be working OK. Have not managed to loosen the little screw at the front and wonder if a tiny drop of fine oil might help but generally the front end looks quite good, so soon I'll probably re-assemble and take the lens for a shoot.

Many thanks to all who offered help.
 
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