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



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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