Re: [Rollei] How to determine number of lens elements

[Richard Knoppow <dickburk >]

At 08:34 PM 01/08/2001 -0800, you wrote:
>No problem!  Take a large screwdriver, a beer can opener ("church key") or
>even a tire iron and gently pry the taking lens out.  then drop it into
>boiling water and simply count the elements as you drain the water off.
>100% accurate.  From there on, things get a little more difficult.  ;-) 
>	
>bob*
>	
>*suffer from dyslexia; hence, my Mother named me "bob" (all lower case).
>-----------------	
>
>
>...<snip the first two> Third, this camera should have the latest made
>6-elements Planar. How can I
>detect it, if it is possible?
>
>Thank you in advance for any comment, which will be really welcome.
>Ciao
>Guido

 A rather less destructive method is to shine a flashlight or other small,
bright source into the lens and cound the reflections. Glass-air surfaces,
even coated ones, will be bright; cemented surfaces will be dim but
visible. Care is necessary when looking for the reflections from cemented
surfaces since a strongly curved one may result in very small or very large
reflections which may be hard to see. 
  The five element Xenotar, both f/2.8 and f/3.5 has its cemented surface
in the second front component (next to the stop). The Planar came in two
versions; the f/2.8 had the cemented surface in the front component, the
f/3.5 with the cemented surface in the rear component nearest the stop.
Both the Xenotar and Planar six element f/3.5 lenses are conventional
Biotar types with the cemented surfaces in the front and back components
nearest the stop. 
 Using the flashlight method the five element lenses will have four
reflections on one side and five (one very dim) on the other. Six element
lenses will have five reflections (one very dim) on both sides. 
 

- ----
Richard Knoppow
Los Angeles,Ca.
dickburk  

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