| 摘要 |
PURPOSE: To provide a telescopic photographic lens having excellently compensated aberrations, a small number of lenses and a behind diaphragm in spite of a small telescopic ratio. CONSTITUTION: This telescopic photographic lens is composed of four-group four-lens constitution composed, in order from the object side, of a first positive meniscus lens whose convex surface confronts the object side, a second positive meniscus lens whose convex surface confronts the object side, a third bi-concave lens, a fourth bi-convex lens and a diaphragm and satisfys the conditions ((1) 0.30<Σd/f<0.40, (2) -0.6<f/f123 <0.2, whereΣd is the sum of on-axis thicknesses and air gaps of lenses, f is the composite focal distance of the whole system and f123 is the composite focal distance from the first lens to the third lens).
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