Canon LTM 100/3.5 with fungus??? Help!!

Canon M39 M39 screw mount bodies/lenses
Bingley

Bingley

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I've been looking for a nice 100/3.5 for some time, and finally thought I'd found one on evilbay. Seller had good feedback, pictures of the lens indicated excellent condition. I took the plunge, and it arrived today. The exterior is beautiful, and the front and rear elements appear to be in great shape. However, shining a flashlight through the lens, one of the internal elements appears to have splotches/small cloudy patches (not all over, just in certain places on the element). Fungus? Could a cleaning take care of the problem?

What to do?

(1) Contact the seller and return the lens for a full refund. Problem is, I don't know when I'd find another example of a 100/3.5 in such otherwise excellent condition. But if this problem is not fixable, return the lens I must.

(2) Suck it up, get the lens cleaned, and keep it. Any recommendations for lens cla's, and what these usually cost?

My purpose was to find a compact small tele for travel, and I'm finding I like the 90 mm focal length (the uncoated Elmar I've been using of late is a loaner).

Thoughts? Suggestions? Advice? What say you?

Thanks
 
There is no way to predict how well or how badly the cleaning will go.
If it looks bad, I would return it.

all black 100/3.5's are indeed hard to find
and for some reason very often have fogging / fungus problems

the chrome or chrome/black 100/3.5's are a lot easier to find

Stephen
 
I would endorse that. The by-product of some starins of fungus can etch the glass. If that has happened, the lens is a goner. Other forms clean very well but you are unlikely to know until it is cleaned. How lucky do you feel? Is the seller prpared to contibute anything toward it?

Kim
 
I had the same problem before. Canon lenses have a rather soft coating in the inside element. You are likely to loose this coating after cleanning, and maybe the glass is etched.
 
It's a very nice lens, but your current example is a crap shoot. It can probably be cleaned by a respectable pro for about $65-75, but there is no guarantee you will not get a clean lens with etched inner glass, i.e. unusable. I'd contact the seller, and advise him of the problem, and the possible solution. If he's willing to absorb part of the cost and the risk of a returned bad lens, that becomes a different picture. If not, I'd return the lens.

Harry
 
Canon 100/3.5

Canon 100/3.5

I recently had a very similar experience with a purchase of an early Serenar 100/3.5. The seller, whom I believe was quite honest and unaware of the issue (which could not be seen without shining a flashlight through the lens), agreed to pay half the cost of cleaning and to take back the lens for a refund if the cleaning does not solve the problem.

Incidentally, the quality of the leather and embossing on the early Canon cases is quite high. It seems to me that the quality of this aspect of production declined through the fifties, although my personal knowledge is admittedly limited.
 
This fogging problem is always on the same internal surface of Canon lenses, that is the surface facing forward to the aperture blades. I was told years ago that this was caused by a phosphorous compound Canon used in the helicoil grease, but why it should always occur only on the one element wasn't explained.
I have a black and chrome 3.5/100 where the glass of this element is cratered like the moon, and a replacement lens head I bought on Ebay was just as bad.
However a 2.8/28 looked completely opaque until I polished off that coating, and now it is a wonderful performer.
With some of my lenses the problem recurs, and with a couple I've replaced the helicoil grease, but can't remember which ones! I should keep a log of all my Canon R/F lenses and methodically regrease them all - quite a task with more than thirty of them. Canon R/F lenses seem more resistant to fungus than many other makes, and fungus is a real problem here in hunid sub-tropical Brisbane.
 
My understanding is that Nikon and Canon lenses have consistently hard coatings, and that it's the Leica lenses with the incredibly soft internal coatings. Certainly, a collapsible Summicron is the only place I've encountered a soft internal coating.
 
Things get more complicated...

Things get more complicated...

First of all, thank you all for responding.

This morning, in an effort to document the problem photographically, I shot a number of pix through this lens (using BW400CN). I expected to see blurry areas on the prints, but the exact opposite turned out to be the case. To my relatively untutored eye, I can't see evidence that whatever-it-is on the internal element is ruining the picture. I've posted a couple of samples below. Shouldn't splotches of haze or fungus affect the end result? In other words, do I really have a problem w/ this lens, or can I ignore the splotches on the internal element if it does not appear to affect results? I admit to being a novice on these issues, but I also want to proceed cautiously before contacting the seller to return the lens. (And, the rest of the lens, including the front and rear elements, appears to be in very good shape).

Thanks for your patience, and advice.

1593234267_19676d67f3.jpg


1593234847_428dd904e1.jpg
 
I got the same lens, and with 'certainly' the same cloudy internal glass. I use my lens as my favorite tele lens because it is so sharp wide open. I noticed that some shooting condition can affect the picture, particulary when shooting in counter light. I adjust the contrast with PS so no big deal, and I always like that vintage lens effect I get from that lens (same as the canon 35mm 1.8)!
 
The picture of the Radio Flyer indicates a very fine lens. Ask the seller to contribute to a CLA just to make you feel better. Enjoy the lens.
 
Thanks, Wayne. I was pleasantly surprised at how that shot turned out, too. I am both a newbie and a klutz when it comes to things mechanical (a dangerous combination), but to my great fortune the Lone Ferider rode to the rescue, and graciously offered to clean the lens! So the lens is on its way to Roland, along w/ my hearty thanks. Is this a great forum, or what?
 
Roland is gracious. A great person for sure! If he offers you a lens, you can count on it being a good one.

Yes, this is a wonderful family.
 
A happy ending...

A happy ending...

I'm pleased to report that this story has a happy ending. Roland, having graciously volunteered to clean the lens, did a splendid job, so that the internal element is now a thing of beauty. 😀 Life is good. Roland is an RFF god. And the lens is a keeper. Once again, is this a great forum or what? 🙂

Thanks!!!
 
You are embarassing me, Steve 😱

It's a cute little thing that lens, and quite sharp I thought.

Best,

Roland.
 
That was an amazing gesture of generousity, ferider. A lot of trouble for you with no gain in any department but to increase your good reputation. You're a nice guy, fer shure.
 
Roland -- Did you delete your response to my last post above? I thought it was pretty funny, and put a nice ending on this thread... clearly, there is, er, no "one size fits all" lens!🙂
 
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