US PATENT SUBCLASS 359 / 691
.~.~.~ Two groups

Current as of: June, 1999
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359 /   HD   OPTICS: SYSTEMS (INCLUDING COMMUNICATION) AND ELEMENTS

642  DF  LENS {32}
676  DF  .~ With variable magnification (e.g., zoom type ) {6}
683  DF  .~.~ With mechanical compensation {6}
691.~.~.~ Two groups {1}
692  DF  .~.~.~.~> + - Arrangement

DEFINITION

Classification: 359/691

Two groups:

(under subclass 683) Subject matter wherein two groups move independently of each other and these groups function respectively as (1) a variator movable for varying the focal length and (2) a compensator which moves independently of the first group for compensating for image plane deviation during focal length variation.

SEE OR SEARCH THIS CLASS, SUBCLASS:

686+, for mechanical compensation with variable magnification having four groups.

689+, for mechanical compensation with variable magnification having three groups.