| 摘要 |
A four-group type telephoto lens system including a super-telephoto range having a viewing angle (2 omega ) of less than 8 DEG and which includes a focusing lens in a first lens group. The lens system includes for lens groups. The first group is composed of a first sub-part having a positive refractive power, a second sub-group having a negative refractive power, and a third sub-group having a positive refractive power. The second group has a negative refractive power, the third group a positive refractive power, and the fourth group a positive refractive power. Zooming is effected by moving the second group, while focusing is carried out by moving only the third sub-group of the first group.
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