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Bojan
Tinkerer
Username: Bojan
Post Number: 6
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 27, 2010 - 04:04 pm: | 
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There is some fungus inside this lens (it is with internal focus mechanism, like the one lowe on this page:
http://www.mir.com.my/rb/photography/companies/canon/fdresources/fdlenses/300mm. htm#f4.0L)..
I tried to clean the internal filter with windex and soft tissue and apparently it was a success..
Now I want to clean the rest of the glass.
Does anyone know how to dismantle this lens? |
Bojan
Tinkerer
Username: Bojan
Post Number: 7
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 02, 2010 - 04:56 am: |
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I managed to dismantle the lens..
Fungus was easy to clean with windex...
However, the middle element (meniscus) had a bit of haze.. and I couldn't wash that with anything I tried (windex, dishwasher detergent, isopropil alcohol).
What could that be and how to get rid of it?
I hope it's not the glass surface damaged. |
Lufthummel
Tinkerer
Username: Lufthummel
Post Number: 1
Registered: 12-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 13, 2011 - 07:09 am: |
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Hi Bojan,
any tips on dismantling the lens? I own the same, also with fungus on the middle element. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 165
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 13, 2011 - 12:22 pm: |
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I have a Canon FD 400mm f/4.5 with IF that also has a bit of fungus. Some of the fungus is located down within the IF elements. I asked here for advice on dismantling it and was told that I'd better not, unless I had the proper optical tools for reassembly. Otherwise, the lens will not function properly at all. Apparently, the IF section must be reinstalled using measurement equipment that only your better techs will have. So I've left mine alone for now. I plan to take it to a professional camera repair facility for the cleaning. It'll probably cost me around $150, but it'll be worth it.
You might try cold cream on the "haze." It works well for fungus removal, but might not do anything for the haze. Still, won't hurt to try, I reckon. |
Bojan
Tinkerer
Username: Bojan
Post Number: 9
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 13, 2011 - 02:49 pm: |
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Guys, I dismantled and re-assembled the lens without problems.. the only tricky part was adjustment of focus assembly, but this is also not a problem and no special tools are needed (only camera with live feature and computer screen to watch the focus)
In my case, it was not the fungus but fogging - it seems the middle element is oxidised (meaning coating is damaged by moisture) and the lens is a bit affected - I am using it for astro-photography and ANY contrast deterioration is most unfortunate.
Otherwise the lens functions perfectly
 |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 167
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 13, 2011 - 05:43 pm: |
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Well, since your primary use is astrophotography, sun-induced flare shouldn't be an issue, which is probably the most serious problem that meniscus lens will face. So it seems to me that if you could safely remove the coating without damaging the glass, the lens will still perform well for your purposes. |
Bojan
Tinkerer
Username: Bojan
Post Number: 10
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 14, 2011 - 02:16 am: |
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This is what I thought myself... but how?
Coating is sometimes harder than glass (being oxide, rare earth or whatever).
I was thinking, this element may need polishing, but I can't do it myself (too risky) and the quote I had was simply not acceptable. So for now I am looking for damaged lens (with this element intact) or for another one - in the meantime I am dealing with the problem by some special processing procedures (basically removing backround) |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 168
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 14, 2011 - 06:35 am: |
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I have a suggestion. Consider a plastic polish, like Hut. Here's a link to it at Woodcraft:
http://www.woodcraft.com/Product/2005771/17469/HUT-Ultra-Gloss-Plastic-Polish.as px
I use this stuff for polishing out shellac and lacquer finishes on guitars. It is designed to polish acrylic, so its abrasiveness is extremely fine. I don't know whether it will be hard enough to remove coatings. But it isn't all that expensive, and you should be left with a shiny piece of glass if it does work. |
Bojan
Tinkerer
Username: Bojan
Post Number: 11
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 15, 2011 - 01:18 am: |
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Thanks, will try... :-) |
