Zoom lenses for enlarger and printers
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What
the Variogon is for the photo and film technology, the Betavaron
is for enlargers and printers: a lens with a continuously variable image
ratio combined with constant high imaging quality. While up to now
several fixed-focal-length lenses have been required for different
enlargement sizes, these have now been replaced by a single lens - the
Betavaron. It is world-wide the first zoom lens for enlargers and
printers.
Intended
at first for traditional enlargers and printers, the Betavaron also
finds use today in OEM-applications modified for individual
customers for their specific purposes.
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The typical Betavaron
for enlargers
in Fig. 1 makes possible, in addition to completely new picture effects,
a considerable simplification of enlarging procedures, thus
significantly reducing the time and effect hitherto required for these
tasks.
After the
correct aperture setting and exposure time have been determined for a
specific image ratio, when that image-
ratio is changed, the required correction of aperture and exposure can
then be ascertained by referring to a table.
pdf
(2,8 MB): 
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Fig. 1: Betavaron 3,1 ... 10 /
0,08
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With the exemplary Betavaron ( Fig. 1), at a
constant distance between negative and positive, changes in the scale of
reproduction from 3.1- to 10-fold can be made continuously. The value
0.08 characterizes the numerical aperture on the negative side.
Especially coordinated close-up lenses, which
with the help of a bayonet can be attached to the zoom lens, give the
user a wide range of applications.
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After a
one-time setting on the enlarger,
the positions of Negative (A), Positive (B), and Enlargement lens (G, F)
relative to one another remain constant.
By simply
moving the focusing ring (F) for the image ratio, the desired enlargement or
that part of the negative which completely fills the frame can be easily and
quickly focused for the desired positive format. In so doing, the sharpness
and imaging quality is fully retained over the entire focusing range. The
diaphragm is adjusted with the knurled ring (G). Fig. 2 left: Enlarger with Betavaron
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As an example of solutions for specific
customers, the adjacent figure
shows a complex industrial application with a fast motorized zoom lens.
The optical construction is based on a modified Variogon.
E-mail: industrie@schneiderkreuznach.com
Fig 3 right:
An electronic/mechanical/optical modular unit
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Variogon zoom lens
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