Re: [Rollei] Coating Flaws in E Series

[Richard Knoppow <dickburk >]

At 09:52 AM 06/17/2002 -0700, you wrote:
>I have a Planar 3.5 E front element that looks like it's been sandblasted.
>Under a very strong loupe it looks like something has eaten a thousand small
>pits in the glass.  I'm contemplating wether I want to get it redone or not.
>In theory, taking off enough glass to fix the surface to fix the surface
>should change the figure, but all of the anecdotal feedback I've gotten from
>people who have had polishing/recoating done by reputable technicians have
>been very positive.
>
>Gene
  I've seen this a number of times on lenses stored where there was a lot
of moisture. It may be the effect of fungus but I suspect it may be
something else. 
  Most coatings are Magnesium Flouride, a fairly hard and resistant
material. I don't know specifically what attacks it but have seen enough
lenses with damaged coatings, or damage which is much deeper than the
coating, to think it may be sensititve to moisture or the exudations of
fungus. 
  BTW, I also remember a runor that Schneider had coating problems in the
mid 1950s. My 2.8E shows some coating flaws on the outer surface but
neither of my Xenars do nor does a Componon enlarging lens from about the
same period. Actually, the Xenars are older, so may not have been coated in
the same way. 

  >----- Original Message -----
>From: "Craig Roberts" <crgrbrts  >
>To: <rollei  
>Sent: Sunday, June 16, 2002 8:29 AM
>Subject: Re: [Rollei] Coating Flaws in E Series
>
>
>> Douglas Cooper said:
>>
>> "...the Xenotar had spots -- almost flakes -- in the coating...I had (it)
>> recoated by Focal Point, and it was stunning."
>>
>> Good morning,
>>
>> When I acquired my 2.8E Xenotar recently I noticed what looked like a
>slight
>> haze on the front element. However, when I examined the lens from the rear
>> with a strong light shining through it, I was shocked to see the same
>> "pin-prick field" coating damage you mentioned, Douglas. I suspected
>> mechanical damage (abrasive dirt blown onto it or something similar), but
>> the viewing lens was unmarred.  Hmmmm.
>>
>> Well, even though the image quality produced by this Schneider lens was
>> outstanding and, as you say, seemingly unaffected, I sent it off to John
>Van
>> Stelten for recoating.  He has it in his kind custody as we speak.
>>
>> In other words, you are not alone. Perhaps we should ask John if he sees a
>> disproportionate number of Xenotars exhibiting this coating anomaly.  By
>the
>> way, have you noticed any improvement - especially in flare resistance -
>> since John performed his procedure?
>>
>> Craig Rioberts
>> Washington, DC
>>
>>
>>
>
>
- ----
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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