[rollei_list] Re: Bayonet II
- From: CarlosMFreaza <cmfreaza@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Wed, 3 Nov 2010 08:19:47 -0300
Robert:
According to my measurements, while my 3.5F Planar
diameter is about 25mm as you wrote, the Rolleicord IV Xenar 3.5/75
diameter is about 20mm, you can notice the difference without
measurement and then I guess the Rollei TLR Tessar 3.5/75 diameter is
also about 20mm; the Rolleiflex T Tessar could be a special case
because it was recalculated and the new formulae could be the
explanation for the diameter difference regarding the older TLR Tessar
(guessing the diameter for the older one is about 20mm and your T
Tessar measurement is right).
The BII size was created for the Rolleiflex 2.8 A in 1949, it appeared
again in 1956 for the Rolleiflex 3.5E (or C) provided with the new
Xenotar and Planar 3.5/75 five elements lenses, the bayonet II
external flanges position is different for the 2.8A and 3.5E causing
incompatibility issues for some accesories like the lens hood,
however no problem with filters. The 3.5E BII was used for the 3.5E2
and 3.5E3 and for the 3.5F too. A special mention for the Rolleimagic
I and II, they also use this BII size in spite of the 20mm diameter of
the Xenar lens, it almost looks like a lens hood for these cameras.
The Rolleiflex T with the recomputed Tessar appeared in 1958 when the
BII size had two years of use for the 3.5/75 five elements lenses, the
T was built to cover the price gap between the 'cord and the 'flex and
the BI size for this camera could be a marketing decision to keep
differences with the 'flexes top models, it was not the case for the
BII Rolleimagics that were very different Rolleis thought for the
amateur market mainly (f.e. the Rolleimagic focusing system moving the
lens first element only and the 1/30 slowest shutter speed put them
out of the pro market at least in theory).
In other words and for any case, while the bayonet size has some
relationship with the lens first element diameter and others technical
reasons, it also could have relationship with F&H TLR cameras and
accesories production and marketing decisions.
Carlos
2010/11/2 Robert Meier <robertmeier@xxxxxxxxx>:
> According to my measurement, the diameter of the front element of the 75mm
> Tessar on my Rollei T is 25mm. The Rolleiflex T takes bayonet I
> accessories. I then measured the diameter of the front element of the 75mm
> Planar on my Rolleiflex 3.5F. It also is 25mm in diameter. The Rolleiflex
> 3.5F takes Bayonet II accessories. This leads me to wonder why F&H created
> bayonet II in the first place. Anyone know?
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