| 摘要 |
PURPOSE:To perform high-performance floating while compensating excellently aberrational variation when a body in a wide long and short distance range is put in focus by composing a photographic lens of four lens group and moving them under specific conditions. CONSTITUTION:This photographic lens has four lens groups, i.e. 1st, 2nd, and 3rd lens groups I-III with positive refracting power and a 4th lens group TV with negative refracting power. When focusing is performed from an infinite-distance body to a short-distance body, the 1st-4th lens groups I-IV lens groups I-IV are moved toward the object side so that three all of air gaps formed of two adjacent lens group respectively increase. Consequently, a large-diameter-ratio, high-performance photographic lens obtained which utilizes floating while aberrational variation at the time of the focusing of a body in a wide range wherein photographic power is larger than unmagnification is compensated excellently.
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