Optical objective with extended varifocal range
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United States of America Patent
Stats
-
Apr 8, 1980
Grant Date -
N/A
app pub date -
Dec 2, 1977
filing date -
Dec 4, 1976
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An objective of a photographic or cinematographic camera has an adjustable four-component front lens group and a fixed rear lens group. Axial displacement of the movable second and third components of the front group establishes a normal varifocal range in which the overall focal length varies between a minimum value f.sub.min and a maximum value f.sub.max having a ratio of 1:6. In the presence of a front attachment with a negatively refracting additional lens member, further shifting of the two movable components establishes an extended wide-angle range with focal lengths smaller than f.sub.min ; similarly, in the presence of a front attachment with a positively refracting additional lens member the two movable components are shiftable to establish an extended telephoto range with focal lengths greater than f.sub.max. Between the normal and wide-angle ranges the third component is also shiftable, without attachment, to focus in a macro range.
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Cited Art Landscape
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