news:379d63ab-7e0f-4c44...@e37g2000yqa.googlegroups.com...
There were a number of lenses available in "casket"
sets, both Zeiss and Bausch & Lomb sold such sets but other
variations on the design were also available. Rudolf
Kingslake shows five variations of five element cemented
lenses in his book on lens history. All have similar
performance. The Turner-Reich lens, which was probably
designed by Ernst Gundlach is a five element cemented lens
very similar to the Series 7 Protar but with one of the
elements split, perhaps to get around the Zeiss patent. The
T-R lens was also available in sets. Its performance is not
as good as the Zeiss or B&L protar but lots of triple
convertible T-R lenses were built on military contract
during WW-2.
The advantage of the Protar Series VII over the Dagor
is that the individual cells are corrected for coma so they
are sharper over a considerably wider angle than a single
Dagor cell. The Dagor as a combined lens is free of coma
because of the symmetry. A combination of Protar cells is
further corrected for coma by the symmetry or near symmetry
even when cells of different focal length are combined.
While none of the single cells is as good a lens as a
complete lens they were good enough when work was done on
large format which was not enlarged or at not enlarged much.
They were an economy where a commercial photographer wanted
to have the resources to do a variety of work. B&L included
an extra-wide-angle Protar in their largest combination sets
with either a Volute shutter or an adaptor plat so that it
could be used on the Compound shutter usually supplied with
the set, as a front shutter.
There are some old Zeiss and B&L catalogues at
http://www.cameraeccentric.com which show the variety of
protar lenses sold by both Zeiss and B&L and, I think, also
a Gundlach catalogue or two. Ernst Gundlach discovered the
method of splitting elements of existing designes as a way
of bypassing patents pretty early. I don't think much of
Gundlach lenses but the company also made Korona cameras
which were pretty good.
--
Richard Knoppow
Los Angeles
WB6KBL
dick...@ix.netcom.com