| 摘要 |
Six groups of six lens elements for use in the photographic arts include a front lens group of three groups of three lens elements, and a back lens group of three groups of three lens elements. The front and back lens groups are symmetrically arranged on either side of a diaphragm mounted therebetween. The whole objective is extremely small in size and has little variation in distortion aberration caused by variation in magnification. In addition, both the image field of curvature and the coma aberration are sufficiently corrected for field angles up to 70 DEG or so under unitary magnification.
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