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Tamron CZ/C 500
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PostPosted: Fri Sep 24, 2021 11:18 am    Post subject: Tamron CZ/C 500 Reply with quote
I just won an auction for this lens and it arrived this morning. Cosmeticaly and mechanicaly it is in absolutely fabulous condition, it looks factory fresh and the case is immaculate as well. But, to my massive disapointment, it has a lot of fungus throughout which was not mentioned in the listing. I would normally just return a lens like this but wonder how difficult these are to take apart and clean, it seems such a shame that its probably a write off.
Has anyone ever dismantled and cleaned one of these old beasts, I would be tempted to have a go but can't find an optical layout diagram anywhere, any advice most welcome.
For some reason the sheer size of this thing and its apparantly unused condition are making me reluctant to return it. Is that sad?


PostPosted: Fri Sep 24, 2021 12:53 pm    Post subject: Re: Tamron CZ/C 500 Reply with quote
bychance wrote:
I just won an auction for this lens and it arrived this morning. Cosmeticaly and mechanicaly it is in absolutely fabulous condition, it looks factory fresh and the case is immaculate as well. But, to my massive disapointment, it has a lot of fungus throughout which was not mentioned in the listing. I would normally just return a lens like this but wonder how difficult these are to take apart and clean, it seems such a shame that its probably a write off.
Has anyone ever dismantled and cleaned one of these old beasts, I would be tempted to have a go but can't find an optical layout diagram anywhere, any advice most welcome.
For some reason the sheer size of this thing and its apparantly unused condition are making me reluctant to return it. Is that sad?


Dismantling and cleaning a vintage zoom lens usually is not that easy, especially when you have no additional information on its construction and repair. I have done so successfully (e. g. with the rare Mamiya CS 3.5/45-90mm lens; see here: http://www.artaphot.ch/mamiya/mamiya-cs-objektive/433-mamiya-cs-45-90mm-f35-repair), but it requires time, a calm and concetrated mind, and the tools needed.

I have no idea what you paid for the lens (I recently got the much better and newer Tamron SP 5.6/200-500mm for CHF / USD 80.--), but if it wasn't that expensive I would keep it and put in on a shelf - for later repair. As you said it's often difficult to get these rare lenses, and maybe the seller is willing to refund 30%-40% ..??

S

EDIT Where does the fungus grow? Some parts of the lens (e. g. the front group) may be pretty easy to remove. Often it's the space between front group and zoom group which is prone to fogging and/or fungus! Maybe you are lucky Wink


PostPosted: Sat Sep 25, 2021 10:09 am    Post subject: Reply with quote
Hi Steve, thanks for the reply, the fungus is throughout the whole lens, front centre and rear and pretty heavy. I contacted the seller and made him an offer of £25.00 for it and enclosed some pics of the problem. For some reason he gave me a partial refund (without any agreement) for much less that I asked for, I reiterated that I wouldn't pay any more than £25.00 for it. Then,I get the whole balance refunded via the eBay return opton, (with no explanation from the buyer) and the eBay return won't let me print off the return label. Confused So, I don't know if he wants it back or not.

Here are some quick and dirty pics of the problem, I assume that that is actually fungus.








If the seller dosn't want it back I won't have anything to lose I suppose, so I think I will have a go. It will still be a good cabinette queen if i mess it up.

Steve, that Mamiya CS 3.5/45-90mm repair looked like a real mission, what was that gunge you cleaned off.


PostPosted: Sat Sep 25, 2021 11:49 am    Post subject: Reply with quote
The front group should be easy enough to get at. It gets difficult when you have to clean the middle elements


PostPosted: Sat Sep 25, 2021 12:19 pm    Post subject: Reply with quote
Tamron lists this model as having 14 elements in 8 groups- http://translate.google.com/translate?hl=en&sl=ja&u=http://www.tamron.co.jp/data/old-lens/cz500.htm

The later model 200-500mm f6.9 06A also has 14 elements in 8 groups, and its layout is here. The minimum focusing distance is identical (3 metres).


"after comparing the optical designs of this lens to its predecessor, that Tamron's goal was to reduce the rather strong chromatic aberration and lateral color within the earlier optical design."

Make of that what you will!

Coincidentally I have a 06a to repair but have only got the first element out so far. There is air space between that and the doublet. I imagine the fungus in your picture is on the surface of this doublet- this should be pretty easy to reach from the front. I have not tackled the rear yet.

There is a very partial disassembly of the 06a here, where someone puts a telescope objective in it
http://khanasuke.blog1.fc2.com/blog-entry-469.html?sp

apart from the text there is only one image of disassembly:



Hope this helps! For what it's worth mine doesn't perform great, wide open is good 200-400 but much sharper in that range at f8. It falls apart with spherical abberation beyond this point at close focus wide open, better at f8 but cleaned up at f11. Even the f5.6 model after wasn't the best.


PostPosted: Sat Sep 25, 2021 7:12 pm    Post subject: Reply with quote
bychance wrote:
Hi Steve, thanks for the reply, the fungus is throughout the whole lens, front centre and rear and pretty heavy.
If the seller dosn't want it back I won't have anything to lose I suppose, so I think I will have a go. It will still be a good cabinette queen if i mess it up.


Sounds reasonable. If you didn't pay that much I would keep it, maybe cleaning the front group first and leaving the rest for a later day ...

bychance wrote:
Steve, that Mamiya CS 3.5/45-90mm repair looked like a real mission, what was that gunge you cleaned off.

All the Mamiya CS 3.5/45-90mm lenses have this problem. Obviously a internal rubber baffle was decomposing early, ending up as a terrible goo. It seems only a handful of theses has survived. Production numbers must have been very low (mine has SN 10089, indicating the 89th lens manufactured). I was really lucky to get one; it was the only one I ever saw for sale - even the Mamiya CS 2.8/21mm seems to be less rare ...

eggplant wrote:
... For what it's worth mine doesn't perform great, wide open is good 200-400 but much sharper in that range at f8. It falls apart with spherical abberation beyond this point at close focus wide open, better at f8 but cleaned up at f11. Even the f5.6 model after wasn't the best.


I only have the f5.6 model which is a "SP" and therefore should be "high performance" - but it isn't, as you said; at least not on our 24 MP FF sensors ...

S


PostPosted: Mon Sep 27, 2021 7:14 pm    Post subject: Reply with quote
Thanks for the helpful replies, I chased the guy up today and apparantly he wants it back but hasn't done anything about organising a return label... Rolling Eyes Thanks for that lens diagram Eggplant, much appreciated.
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