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RE: [Rollei] OT Easy service lens (was felt and plush : a possible source)

At 06:19 PM 02/03/2002 -0500, you wrote:
>That sounds like a cool design.  I wonder why the newer
>lenses aren't as easy to service as your older one?  Not
>that you need to do it often, but dust and other particles
>eventually creep in between the elements eventually.
>> I just got a Zeca 9 x 12 camera with Unofokal lens. This lens is 
>> great and 
>> really easy to clean. It's possible to screw lose all lens elements and 
>> clean them. No cemented lenses, never a risk for separation. :-)

  The problem comes with small sealed cells. While larger lenses very often
have back caps which unscrew many smaller lenses have front retaining
rings. These unscrew too, but it may not be obvous. Many lenses have the
threads painted over so it looks like there is no way of getting them
apart. Retaining rings of this sort are removed by using a tubular friction
tool. A few have slots in them (Schneider does this) but the friction tool
is safer even when there are slots.
  What I've observered is that older lenses often get hazy inside. I don't
know the source of the haze definitely but I think it may be something
evaporated from the anti-reflection paint in the cell. In any case it comes
off very easily once you can get access to the lens surface. 
  This haze completely destroys the contrast of the lens. I suspect many
old lenses which are thought to be low contrast due to lack of coating are
actually just dirty. 
- ----
Richard Knoppow
Los Angeles, CA, USA