Re: [Rollei] Cleaning fog from Xenar

[Richard Knoppow <dickburk >]

At 11:15 PM 05/05/2002 -0400, you wrote:
>I'm wondering if anyone here has opened a Xenar to clean light fog off the
>inside surfaces.  Is it easy?  Better left up to a pro?  And what kind of
>tools would I need to get it unscrewed?
>
>Also, off-topic [Leica]:  I'm trying to relubricate the focusing helicoid on
>an old 50/3.5 screw mount Elmar.  Lighter fluid freed it up a lot, but I'm
>wondering what I can put on there that will truly lubricate.
> 
>
>Douglas Cooper
>http://www.dysmedia.com
>
>NO ARCHIVE
>
  The Xenar is pretty easy to get open (I assume you mean the front cell).
The front element is held in by a threaded retaining ring (the thing with
the lens name on it). While it has small slots for a spanner its safer to
remove it with a friction tool. The friction tool is simply a length of
tubing the right diameter with some soft rubber cemented to the rim at one
end.
  A great many lenses have retaining rings which are not slotted and are
removed this way. There are no spacers in the Rollei Xenar. The haze will
come off with lens cleaner or pure alcohol. Lately I've been using a
"streak free" type window cleaner for lenses. This stuff contains
2-Butoxyethanol and is the kind recommended by Hewlett-Packard and others
for cleaning scanner windows. Its more effective than the usual Ammonium
carbonate lens cleaner.
  You must remove the front trim panel from the camera to remove the Xenar
front cell but you can get the element out with the cell in place. 
  The viewing lens has set a set-screw on its side. The lens must be
removed from the camera to work on it. I've found a couple of viewing
lenses that had what appeared to be dropletts of oil on the glass. Whatever
it was came off with lens cleaner.
  If you clean the viewing lens be very careful to note the position of the
spacer inside and the direction of the center element. This element look
very nearly bi-convex but isn't. If you get it in backward the lens will
not focus.
  A great many lenses develop a haze inside sealed cells. It appears
sometimes in lenses which are only about twenty years old, and not at all
in some older ones. Old Wollensak lenses do not seem to get hazy. Kodak and
Schneider lenses do and the haze destroys the contrast to an amazing degree. 
  Zeiss Tessars as used on Roleiflexes also have front retaining rings.
Larger ones have threaded back caps which are very easy to get off. 
- ----
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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