| 摘要 |
An imaging lens system includes a first lens having a meniscus profile with a convex surface facing an object side and having a positive refractive index; an aperture diaphragm; and a second lens having a meniscus profile with a convex surface facing an image side and having a positive refractive index, wherein the first lens, the aperture diaphragm, and the second lens are arranged in this order from the object side. The imaging lens satisfies conditional expressions where f represents a focal distance of a total lens system, f1 represents a focal distance of the first lens, and L represents a distance on the optical axis from the surface on the object side of the first lens to an image plane wherein calculation is done in terms of an air-equivalent thickness for a back insertion glass, and n(ave) represents an average value of refractive indexes at d-lines of the first and second lenses.
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