Re: [Rollei] Why the 6-element lens for 3.5Fs

["Richard Knoppow" <dickburk >]

- ----- Original Message ----- 
From: "Marc James Small" <msmall  >
To: <rollei  
Sent: Wednesday, April 30, 2003 2:31 PM
Subject: Re: [Rollei] Why the 6-element lens for 3.5Fs


> At 01:17 PM 4/30/03 -0700, Nick Roberts wrote:
> >
> >I have several times heard the story that some of the
> >original 5 element Planars were incorrectly assembled
> >with an element reversed - now is that an old wives'
> >tale (as I'm inclined to believe) or is it true? If
> >so, it could explain a 50% batch rejection rate.
> >
> >As a final aside, when was the Xenotar modified?
> >
>
> Nick
>
> The story about the reversed elements involves the 2.8/8cm
CZJ Tessar T
> used on the early 2.8A Rolleiflex camera.  I have never
heard this tale of
> the Planar and would doubt it.
>
> The Xenotar was modified between the 3.5F, Type II, and
Type III.
>
> Marc
>
> msmall    FAX:  +276/343-7315
> Cha robh bàs fir gun ghràs fir!
>
  I doubt this is true of even the Tessar. About the only
element which could be reversed without being immediately
obvious is the center element. Reversing it causes an
enormous distortion of the image, not just a little quality
loss. I think its more likely that groups of lenses chosed
to go toghether got mixed or perhaps element spacing was
wrong.
  Since some report good performance from these CZJ Tessars
the design was not the problem. In general Tessars are not
at their best at f/2.8 but can be quite satisfactory.
  Since the same lens was evidently used in the Ikoflex III
it would be intresting to hear from those who have these
cameras as to lens performance.
- ---
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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