| 摘要 |
Variable power lens systems for use with electronic imaging systems, e.g., systems employing CCDs, are provided. The systems take advantage of the fact that the images detected by electronic imaging systems are small, e.g., the image diagonal can be 5.5 millimeters or less. The lens systems employ thick lens elements, whose diameters and thicknesses are large relative to the image size, and large air spaces between lens elements. The systems also employ weak lens units. In this way, simplified lens designs having excellent optical properties at less cost are provided. In certain embodiments, the lens systems contain only three lens elements, e.g., a negative first lens element (L1), a positive second lens element (L2) for zooming, and a positive third lens element (L3), with the first (L1) and/or the third lens element (L3) serving as a compensator.
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