This is also an interesting comment Peter and coinciding in general with the opinons about the Tessar for the 2.8A. I think it's almost impossible to retrofit a 2.8A with Biometars, at least with the Biometars 2.8/80 used for the 2.8B, the Biometar is a five elements lens heavier and bigger than the Tessar, the Biometar required a complete redesign for the lens carrier (lens panel)in the 2.8B and new and bigger lens carrier guide posts. All the best Carlos --- "Peter K." <peterk727@xxxxxxxxx> escribió: > Thank you Carlos. Apparently the only 80mm F2.8 > Tessar that people liked was > the one for the Hasselblad. In my references under > the moniker "Lousy > Lenses" they state the following: > > "One curious example is the f2.8 Tessar, liked in > 50mm form but much less so > in the 80mm versionunless for the Hasselblad where > it was admired!" > > Since that Tessar came much later perhaps Zeiss' > work on the earlier 80mm > F2.8 Tessar helped. I did find that in 1931 Zeiss > listed *a Tessar > *f2.850, 60, 75, 80mm This was designed by Merte. It > is fairly common > and usually > really good but the original 80mm version for the > 6x6cm Super Ikonta was > said to different and less liked by users. So it > does coincide with > Richard's note about the Tessar on Zeiss' own > cameras. > > The only notation specifically for the Rollei 2.8A > reads as follows: "*Tessar > *f2.8 80mm for Praktisix SLR and a few were sold on > Rollei cameras. This > seems to have been an old or pre-war design and was > not up to the standard > expected. There seems to have been a close out in > Jan. 1964. The f2.8 Tessar > had previously been a problem on the Rollei 2.8A in > 1950-1951 when a batch > were sold with Tessars at No2,300,000-3,000,000, > which are wartime or just > post-war numbers. Customers found these of poor > quality and the factory > recalled them. Thus they became a real collectible > through scarcity. A > little later Rollei supplied some cameras with Jena > f2.8 80mm Biometars and > these were much more successful. [It is not known > what happened to the > Tessar cameras, but they may have been rebuilt with > Biometars and sold e.g.. > in E. Germany but this is a uncertain.]" > > Interesting comments about the possibility of 2.8A > models being retrofitted > with Biometars, but no one knows for certain. > > Peter K > > > > > > > > On 11/14/06, Carlos Manuel Freaza > <cmfreaza@xxxxxxxxxxxx> wrote: > > > > Peter, I think Richard K explained several times a > > possible cause: Tessar design limits, they > > manufactured Tessar for 3 decades but never a > Tessar > > 2.8/80 for the 6x6 format, it seems 2.8/80 is an > > extreme design limit for this lens type and then > the > > optical design and glasses must be very exact. > Zeiss > > manufactured the Tessar 2.8/60 for the 4x4 however > the > > increased focal length from 60mm to 80mm increased > the > > problems too and it seems they could solve the > main > > design problems for 1938 when Rollei started to > > develop the 2.8A prototype, but you know this lens > > never was %100 satisfactory, for the reasons > Richard K > > explained several times .- > > > > All the best > > Carlos > > > > > > > > --- "Peter K." <peterk727@xxxxxxxxx> escribió: > > > > > Carlos, > > > > > > Very interesting. Seems odd though that having > been > > > building Tessars for 3+ > > > decades that CZJ would have had issues at this > time. > > > Do you know any reason > > > why this would have happened? > > > > > > Marc, any input? > > > > > > Peter K > > > > > > > > > On 11/14/06, Carlos Manuel Freaza > > > <cmfreaza@xxxxxxxxxxxx> wrote: > > > > > > > > Marc: > > > > On 1934 CZJ developed a Tessar 2.8/80 > lens > > > > prototype for the Rolleiflex Standard, but it > had > > > bad > > > > quality and F&H rejected the lens. > > > > On 1938 CZJ re-designed the Tessar 2.8/80 and > this > > > > time F&H accepted the lens performance > developing > > > the > > > > 1939 Rolleiflex 2.8A 2.8/80 prototype (PR 149) > but > > > the > > > > production couldn't begin due to the war, this > > > protype > > > > was the basis for the 1948 2.8A prototype with > > > some > > > > changes. > > > > I think it's evident the 1938 and 1939 Tessars > > > 2.8/80 > > > > were bought for the 1939 prototype commercial > > > > production and it did not happen due to the > war. > > > > > > > > All the best > > > > Carlos > > > > > > > > --- Marc James Small <marcsmall@xxxxxxxxxxx> > > > > escribió: > > > > > > > > I have no explanation for the > > > > > existence of the Prewar 2.8/8cm CZJ Tessars > -- > > > > > the first Rolleiflex batch was of only 2 > lenses > > > > > and was completed on 2 FEB 1938; the other > > > > > Rolleiflex batches date from the first half > of > > > > > 1939. The Ikoflex lenses all date from 1939 > > > save > > > > > for the final batch of 3 which 29 DEC 1941 > > > during > > > > > the heart of the war years. All of the > Prewar > > > > > lenses were produced to a design dated 27 > JAN > > > > > 1933 but, for that matter, ALL Prewar > 2.8/8cm > > > CZJ > > > > > Tessars were produced to that design save > for a > > > > > single batch of 2 lenses for the Super > Ikonta > > > > > B/BX made to a design dated 20 SEP 1938, but > > > that > > > > > was clearly a test for a planned upgrade > which > > > > > did not occur because of the war. > > > > > > > > > > We do know that Franke & Heidecke was > > > > > substantially concerned over Zeiss Ikon's > move > > > > > from the f/3.5 Tessar in the Ikoflex II and > > > > > II/III to the f/2.8 lens in the Ikoflex III > and > > > > > probably intended to follow suit, though > this > > > was > > > > > precluded for some years because of the > outbreak > > > > > of War. I would suspect that F&H caboosed > their > > > > > order onto the Zeiss Ikon order, as eight of > > > > > these blocks were made in unison in four > linked > > > > > groups and were finished on the same day, > > > > > probably so that both Zeiss Ikon and F&H > enjoyed > > > > > a price break from production economics. I > do > > > > > not have any Rolleiflex 2.8 lens numbers > handy, > > > > > so I cannot be certain of this, but it would > > > seem > > > > > that the lenses used in the 2.8 came from > lenses > > > > > ordered by Rolleiflex and not from left-over > > > > > Ikoflex III lenses. Here is a precis of > these > === message truncated === __________________________________________________ Correo Yahoo! 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