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Archive 2016 · Repair options for 28-70L with fogged glue between cemented elements?

  
 
calemon
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p.1 #1 · p.1 #1 · Repair options for 28-70L with fogged glue between cemented elements?


Hi all:

I have a 28-70L which is my favourite lens. I've discovered that a pair of lenses (a doublet) cemented together appears to have fogged. Most google topics on repairing this are concerning really old and relatively simple lenses (i.e. MF primes). Not too many people write about repairing something as recent or complex as a 28-70L.

Other google results seem to point to people who "specialize" in rebonding lens elements, but not necessarily doing any of the rest of the work. From what I've learned, the element in question is pretty much the "deepest" component in the 28-70 : the entire lens must be completely disassembled to remove the faulty element. I'm pretty sure that this cemented element is the replacement part that Canon is "out of" which caused the 28-70 to go "end of service" in the first place.

A part of me would really like to get this lens repaired, depending on the cost. I don't think I want to try to DIY the re-cementing myself - I'm looking for a true repair I can use or sell with confidence and not something that's just "better than throwing it out". I don't trust the level of dust in my environment and I don't have a clean room (or anything remotely close), UV baking lamps or any of that stuff available.

I do lots of DIY things and I would consider a scenario where I do the lens disassembly and reassembly, and ship only the element to someone trustworthy and preferably in North America (assuming such a person/company exists) to be re-cemented. I worry a bit about Murphy's law, collateral damage during the work, and forgetting how things go together in the time the lens is disassembled waiting for shipping both directions and the repair itself.

Anyone deal with this kind of issue at all? Even better if it was a 28-70L... Most threads on the 28-70 talk about throwing away or finding a donor doublet that isn't fogged yet. I don't want a ticking time bomb with the same design problem. I'd rather repair with either new Canada balsam giving me another 15-20 years, or a newer UV curing glue that will be a permanent fix.

[ FWIW - I read somewhere that the 24-70L series that replaced the 28-70 ceased using this cemented element ]

Some sample reading material:

http://www.largeformatphotography.info/forum/showthread.php?65756-One-way-to-fix-lens-separation

http://www.4photos.de/camera-diy/Delamination-Separation-Repair.html

http://www.skgrimes.com/library/old-news/old-lenses-can-be-restored-by-re-cementing




Feb 11, 2016 at 06:27 PM
Gunzorro
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p.1 #2 · p.1 #2 · Repair options for 28-70L with fogged glue between cemented elements?


As you have found out, sell it on eBay for parts, buy another junker for parts, or use as a paperweight.

Sorry, it's time. The original 24-70L is a better lens and very reasonable these days.



Feb 11, 2016 at 08:09 PM
kezeka
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p.1 #3 · p.1 #3 · Repair options for 28-70L with fogged glue between cemented elements?


You could try contacting KEH and seeing if they think they can work on it. I know they do some repairs, no clue if this is one of them though.


Feb 11, 2016 at 08:14 PM
EB-1
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p.1 #4 · p.1 #4 · Repair options for 28-70L with fogged glue between cemented elements?


I doubt that it is economical to repair. You could buy a used one or something like a used 24-70/2.8.

EBH



Feb 13, 2016 at 12:26 PM
killersnowman
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p.1 #5 · p.1 #5 · Repair options for 28-70L with fogged glue between cemented elements?


Wow those links are wonderful. Such an interesting repair strategy. Personally, I would give it a go. Try to fix it yourself, the worst that can happen is you break your lens, which it is already broken, so just dig deep and take that sucker apart.

I did a diy repair on salt water damage with my Sony A7r by taking it apart and soaking it in distilled water. It was crazy but a worth while experience.

Do it, do it, do it



Feb 14, 2016 at 08:59 AM
scalesusa
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p.1 #6 · p.1 #6 · Repair options for 28-70L with fogged glue between cemented elements?


Like others have said, sell it for parts, you can buy a used one for less than the cost of repairs after you sell the old one.

Disassembling a lens is much more complex than taking a camera apart, I do repair old MF lenses. First thing, you should buy $200 worth of the right tools if you seriously want to take it apart. Then, after reassembly, send it to a third party for re-adjustment. A good used one will cost less in the long run.



Feb 16, 2016 at 11:32 PM
mdude85
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p.1 #7 · p.1 #7 · Repair options for 28-70L with fogged glue between cemented elements?


I have disassembled a 24-105L and a 17-40L before, so I assume that the 28-70 is somewhat similar. It's by no means impossible; there are some decent Youtube videos on the subject; however, it's going to take a while (a day? two days? more?) and there is a very real chance of bricking the lens. Cleaning the interior of the lens, replacing an loose screw, or something to that effect is one thing. Actually replacing or re-bonding lens elements... I'd be wary about my abilities, but yours may differ.


My advice is only take it apart if you are comfortable with the prospect of having to sell it for parts. Which is not that bad -- you could probably get $200-300, perhaps up to $400, on Ebay.



Feb 17, 2016 at 03:27 PM





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