| 摘要 |
PURPOSE:To obtain a lens system having a high aberration correcting effect and constituted so as to be used for a video camera or an electronic camera by constituting the lens system of 1st, 2nd, 3rd, and 4th lenses arranged successively from the object side and satisfying the lens system with specific conditions. CONSTITUTION:The lens system is constituted of the 1st lens consisting a lens having convex faces on both the sides, the 2nd lens consisting of a lens having concave faces on both the sides, the 3rd lens consisting of a positive meniscus lens turning its convex face to the image side, and the 4th lens consisting of a positive lens having a convex face to the image side which are successively arranged from the object side. When respective conditions expressed by the inequality I are satisfied, the lens system highly accurately corrected at respective aberrations can be applied to a video camera and a compact camera type electronic still camera. In the case of executing focusing by moving only the 4th lens, the inequality II will be preferably satisfied.
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