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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 03 Aug 2012 (Friday) 18:29
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Yet another Is This Fungus thread: 28-70mm f/2.8L

 
hk300
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Jun 22, 2013 10:26 |  #16

The 28-70 has a lens element (consisting of 2 parts glued together) which easily oxidated. I guess for this reason this lens element part was quickly used up and is no longer available.




  
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xraqs
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Nov 28, 2013 18:37 |  #17

discojuggernaut wrote in post #14811047 (external link)
Please click here for full size image (external link)

[URL="[URL]https://dl.​dropbox.com/u/2002065/​28-70mm.JPG"]Here's the lens in question[/URL}

I got this as a real cheap craigslist deal but didn't have a flashlight with me nor did i do the due diligence that i should have with a high-ticket as-is item. AF and aperture work fine on it, but there is a yellowish haze cast on images at all apertures and FL, and is clearly visible through the viewfinder. I included some shots at 70mm with other 70mm shots from a different lens.

Is it condensation, oil, broken down lens cement, fungus? Looks like little yellow inorganic spots in my layman's eyes.

I really want to get this fixed, would a cleaning suffice, or would it be impossible if it's between elements?

It shows up in the rear end (the mounting end) of the lens. Otherwise the lens is pristine.

Thanks in advance

Would you buy it? need to repair mine and part i need is not on the market anymore. Please email me at raqs_26@hotmail.com




  
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NemethR
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Nov 29, 2013 07:17 |  #18

I have a 28-70 2.8, wit the same issue.
Sorry to say that bro, but it cannot be repaired,there are no more spare parts anymore :(

Its a known issue with the 28-70 f2.8, the coating of the element is oxidated, and sadly all spare parts have been used up, Canon does not make them anymore, so no chance to repaired. :(

Maybe if you can get another deect copy, that is optically good, you can extract that lens element, and let it be fixed.


Roland | Hobbyst Photographer
Nikon D850 | Nikon 70-200 f/2.8G VR II | Nikon 85mm f/1.8G | Nikon 35mm f/1.8G

  
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discojuggernaut
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Dec 09, 2013 15:43 |  #19

Just an update, i had it repaired by a 3rd-party repair shop that happened to have that cemented doublet in stock. Lens has been working great for over a year and a half. Will eventually sell to fund the 24-70 mkII, but the 28-70 has been a great workhorse.


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Camarinho
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Mar 25, 2014 08:29 |  #20

Hello
I've bought a 28-70 L, with a very similar problem. The solution is rather complicated bu I managed to Fix the lens up to... I'd say 85%. I tryed asking Canon for a replacement part... the part number is: CYI-2532, but is no longer available.
So I desassembled the lens, to the most inner elements doublets and separeted them with acetone... It took me 2 weeks in acetone, because the glue is almost 20 years old. And replaced the glue with a resin used in Histology for microscopic slides. And now the lens Is crystal clear... but I think at 2.8 it is way too soft. I'll soon disassemble it again... remove the DPX resin and replace it with a UV curing special glue for optical lenses.

Hope this helps




  
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ZoneV
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Mar 25, 2014 10:37 |  #21

Camarinho wrote in post #16784652 (external link)
... I'll soon disassemble it again... remove the DPX resin and replace it with a UV curing special glue for optical lenses...

Probably my way of lens bonding could help: I use cheap cheap UHU glass glue instead of optical UV curing glue or Canada Balm (external link).


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Camarinho
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Mar 25, 2014 11:59 |  #22

ZoneV wrote in post #16784911 (external link)
Probably my way of lens bonding could help: I use cheap cheap UHU glass glue instead of optical UV curing glue or Canada Balm (external link).

IMAGE: http://s25.postimg.org/4u5zl10v3/IMG_1018_f2_8_Normal.jpg

IMAGE: http://s25.postimg.org/3vpmiqnj3/IMG_1018_f2_8_Crop.jpg

IMAGE: http://s25.postimg.org/s24v7lz1b/IMG_1020_f8_crop.jpg


The first shot is wide open, the second is Crop. The thir is a crop of the same picture taken at f/8.
Since this my first repair of L glass... do you think that this fits the standards? Any other advice when applying the glue?
Thanks for the advice



  
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ZoneV
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Mar 26, 2014 10:25 |  #23

Camarinho wrote in post #16785109 (external link)
...Since this my first repair of L glass... do you think that this fits the standards? Any other advice when applying the glue?
Thanks for the advice

Don´t know how this lens should be, but I would not be statisfied with it with this images wideopen.
I apply too much glue, and press / move the lenses to get air outside. And to get lenses as much as possible together. Glue should not be a millimeter thick :-)
both lenses need to be very, very exact in right position one to another!


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Guto
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Mar 26, 2014 12:04 |  #24

hk300 wrote in post #16054590 (external link)
The 28-70 has a lens element (consisting of 2 parts glued together) which easily oxidated. I guess for this reason this lens element part was quickly used up and is no longer available.

Thats it. I had same problem.


2 X Fujifilm X-T3 | 16mm f/1.4 | 23mm f/1.4 | 35mm f/1.4 | 56mm f/1.2 |

  
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Camarinho
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Mar 26, 2014 18:09 |  #25

ZoneV wrote in post #16787676 (external link)
Don´t know how this lens should be, but I would not be statisfied with it with this images wideopen.
I apply too much glue, and press / move the lenses to get air outside. And to get lenses as much as possible together. Glue should not be a millimeter thick :-)
both lenses need to be very, very exact in right position one to another!

Tomorrow i'll buy the UHU glass glue and follow your "protocol" for doublets cementing! ;)
I'll Post new pictures here as final result.

During this process I did take some pictures of the disassembly, lens separation and cleaning. So I might make a tutorial on how to fix this lenses, as canon stop servicing them and a lot of people has this issue!

:D




  
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ZoneV
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Mar 27, 2014 02:56 as a reply to  @ Camarinho's post |  #26

Take care for exact element alingment!
In industry special machines are used to optical center the lenses together - for example down to 2 microns tolerance.
Likely you dont get that exact, but try to work as exact as possible.


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Yet another Is This Fungus thread: 28-70mm f/2.8L
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