Full Version: Half fogged rear element group Nikor AF20mm F2.8D...
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Quote:I'd try the oven (not pre-heated and not fast heating up). If it is expoxy based, heat does nothing though.

If all fails, you can try order this group of elements?




Quote:I'd try the oven (not pre-heated and not fast heating up). If it is expoxy based, heat does nothing though.

If all fails, you can try order this group of elements?



  Thanks for the link BC,  the trouble with these chemical products these days is there are so many laws against transporting them, then there are solvent laws because of solvent abusers!!  


  You have a nightmare of a job buying a liter of oil paint!




  Oh onward and upward, or was it downward? 
Canada balsam, I don't think has been used much in modern lenses.  According the Wikipedia (I don't have the link) it has been phased out since the end of WWII due to thermal instability among other reasons.  I think I tend to agree with JoJu.  If you can find a defective lens with an intact rear doublet that would be ideal.  So my dream of fixing my 80's era lens with a little separation are probably just that.


Hi Arthur,

               BTW. I posted a link to a focus breathing video and how to test for it  and get round it on just talk page!


  Looks like modern glues are used in the Nikon, these later types have all the disadvantages of not being able to de-cement the elements while still having the drawbacks of misting.....a neat trick from Nikon! :o

  However I busied myself with a less stressful DIY  job.......the "Toast cooler"  I get the impression that it's maybe the first of it's kind!
That' what the world just was waiting for, dave! Can you do this also in birch, bamboo and redpine?


Now I iunderstand your efforts a bit better, you need to keep yourself occupied with interesting DIY. How about of developing a real cool geared tripod head? The available ones have all kinds of disadvantages and I'm not talking about the price tag... 


 I finished this adapted tripod mount about two weeks ago, it just slots into the camper window blind frame, I've been using it for shooting small birds in the tree 3 meters away, sorry that there's no gearing....as yet! I also have a complete roll of camouflaged cloth which covers the side of the camper 20 square meters of it.


   The hunting season finishes in two days so I can finally go out birding etc. with out having to pick lead-shot out of my butt!    Ouch.... :o


Update on the ill fated AF20 F2.8D lens:


  The couplet has been soaking in acetone  for a long while, then nitro-methane, then xylene,  all to no avail.


  This modern lens cement is resistant to all those solventst!


  "Le chlorure de métylène" (I've already forgotten it's English name) seems to be my last hope, albeit small. The product is available in France in what they call "Drogeries" a sort of hardware store, the trouble is most of these stores have slowly but surely closed down and this product has fallen out of popularity. I've rung around but as yet have not been able to locate a source.

 Having ascertained that the cement isn't and probably hasn't been Canadian Balsam for some years this puts these sort of repairs out of the reach of amateurs as well professionals (the latter being uneconomical).

  I've decided not to take the heating route, as JoJu said, "if you can't dissolve the cement your unlikely to be able to clean the elements".

     In all the years of looking on ebay and the like, I've yet to see a S/H version of this lens come up for spares, maybe this "rarity factor" will put my example in good stead for someone looking for one to exchange his front element or some other part.



 BTW. Reading around the few specialist sites out there, indicates that fogging is often caused by contamination of the glue at the point of manufacture, taking years to appear. A lot of the older D series Nikor zooms have suffered from glue related delaminations, looking with LED torch shows this up very quickly. 


  Oh well, a pity!

If it comes worst, some of your hard core chemical experiments did a good job hardening the glue.

How likely you will find soon a repair lenes on eBay? How likely this will have a - surprise - fogged rear element?

I think if you like to excel in stubborness you can go as well the full path and ask at lensrentals if one of their 20/2.8 D is broken but has a functional rear element.


Hmmm ....Lens rentals, if they still rent such an old lens?...maybe they have a bow full of old D series bits and bobs. I could always send them an email I suppose. Yeah I'll do that later..thanks for the idea!


  In the meantime I'm filming the tree cutting opposite me, I'm using the D750, never filmed with it before, learning as I go, I hope to put a clip on utube when I've worked out how to edit and upload..hey ho!


Bonne chance with filming! If you ever consider a better microphone, do yourself a big favour and look outside of Nikon. Røde has some nice ones...


  Ok at $49 per week I guess you could say I've had my moneys worth then!  I've had it for over a year and a half, as it's still current on Lensrental's site, I can't imagine they want to sell there "spares supply", not to worry!  

  Perhaps I could rent some of my lenses.

   Oh I sold the Pentacon bokeh monster today, actually made some money on it.....like about 3 euros per hour in terms of my labour, no getting rich there then!  Sad Time to trim down on having too many lenses, like lens pruning!

  How's your Tammy G2 doing? I'm still loving mine, you have to stop down a little @ 600mm otherwise it's sharp all the way.

  A few egrets having fish for dinner..




  As for a mic, I'd bought a cheapie from ebay with a "dead cat" on it  Tongue  It turned into a real hooligan of a wind this afternoon gusting 80-100 Kph so even the "dead cat" couldn't  tame the wind noise. I'm still struggling with Avidemux.....saving settings......


  Hey ho! ..  no rush!

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