Re: [Rollei] 2.8 Tessars and 3.5 F - 12/24 function

[todd <todd_belcher >]

Nick,

Actually the 2.8/80 Tessars on the Ikonta Bs were front cell focussing, 
while the Rollei 2.8 Tessars were not. In the latter case, the whole 
lens moved in and out to accomplish focussing. The 2.8/80 Jena Tessars 
that appeared on the Rollei 2.8 A seems to have been from the batches 
made for the prewar 2.8 Ikoflex. Zeiss just coated them and sold them to 
Rollei after the war.

todd



Nick Roberts wrote:
> Todd,
> Thanks for that - I was always confused about the
> Zeiss Jena Tessar/ Zeiss-Opton Tessar before, now it's
> very clear (previous explanations I had seen elsewhere
> got confused with the 2.8B lens, which I knew was
> wrong). Thanks everyone else for pointing out the
> heritage of the 2.8 Tessar - it hadn't occurred to me,
> yet I've always liked the Super Ikontas.
> 
> I really knew about the 12/24 issue (thanks to reading
> it here first, probably) - I just had it fixed in my
> mind that my Planar 3.5F was a similar vintage to my
> Xenotar ones, and that they were all pretty early - so
> 5 element lenses. If it hadn't been for this
> discussion, I would still be none the wiser. It
> doesn't affect what I think of the lens (wonderful for
> B&W), but it is nice to know.
> 
> It's also intriguing that with the reported quality
> control tests there were so many problems - I can but
> assume (again!) that the QC was stepped up as a result
> of these issues - I know I've read of customer
> critisim of all the lenses on the A and B.
> 
> 
> Nick
> 
> --- todd <todd_belcher  > wrote:
> 
>>Nick,
>>
>>There were two Tessars on the 2.8 A - a Zeiss Jena
>>Tessar, and a 
>>Zeiss-Opton Tessar (there is no such thing as an
>>Opton Tessar).
>>
>>I have tried both. Results were varied. The Jena
>>Tessars on the 2.8 A 
>>are prewar lenses that Zeiss coated for Rollei for
>>inclusion on the 2.8 
>>A. some of these lenses were mismatched and produced
>>poor results. 
>>Others of these lenses were perfectly fine.  Rollei
>>then switched to the 
>>Zeiss-Opton Tessar for the rest of the 2.8 A cameras
>>and would swap Jena 
>>Tessars for Zeiss-Opton Tessars when cameras came in
>>for repair.
>>
>>Interestingly, my 2.8 A with Jena Tessar is sharp as
>>a tack. But the 
>>Zeiss-Opton Tessar is soft. I have checked the lens
>>on a collimator and 
>>there is nothing amiss there - the lens is just a
>>dud with very poor 
>>resolution.
>>
>>Regarding 12/24 and Planar lenses. All 3.5 F cameras
>>can be converted to 
>>12/24. It is just that those made after about 1966
>>had much of the 12/24 
>>mechanism already installed in the camera meaning
>>that conversion was  a 
>>reasonably simple matter. 3.5 F (and 2.8F) cameras
>>before this date 
>>require the whole transport mechanism to be swapped
>>for an upgraded one 
>>- a much larger job. So 12/24 is no indicator of a
>>Rollei F camera's age.
>>
>>I was afraid that someone was going to ask when the
>>3.5 Xenotar was 
>>modified. I have absolutely no idea with any
>>accuracy.
>>
>>todd
>>
>>
>>
>>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 an aside, has anybody ever tried the 2.8 Opton
>>>Tessar?
>>>
>>>As another aside, I was convinced my Planar-ed
>>
>>(and
>>
>>>unmetered) 3.5F was a 5 element lens - I had
>>
>>always
>>
>>>assumed that because it wasn't a 12/24 model it
>>
>>would
>>
>>>be too old (yes, I know about assumptions!) and
>>
>>only
>>
>>>checked the serial numbers of cameras and lens
>>
>>this
>>
>>>morning (and the lens coating colour). The
>>
>>interesting
>>
>>>point is that this 6 element lens does not
>>
>>outperform
>>
>>>my (I assume!) 5 element Xenotars - there's a
>>
>>touch
>>
>>>more contrast, and a different colour balance, but
>>>neither newspaper nor brick wall tests can
>>
>>separate
>>
>>>resolving power, even at the edges. Whilst this is
>>
>>in
>>
>>>no way a scientific test, it does make me wonder
>>
>>if
>>
>>>there really is a performance hike with the 6
>>
>>element
>>
>>>lens, or if indeed it was to simplify production.
>>>
>>>As a final aside, when was the Xenotar modified?
>>>
>>>Nick
>>>
>>>__________________________________
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>>
>>
> 
> 
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