| 摘要 |
PROBLEM TO BE SOLVED: To provide an image capturing lens system which allows for capturing images at a wide angle and offers superior telecentricity and reduced shift in in-focus position and degradation of MTF with temperature changes ranging from a low temperature to high temperature.SOLUTION: An image capturing lens system comprises a first lens having negative power and a concave image-side surface, an aperture stop, a second lens having positive power and a convex image-side surface, and a third lens having positive power and a convex image-side surface in order from the object side. The first lens is a plastic lens. Of the second and third lenses, the one with a longer focal length is a plastic lens and the one with a shorter focal length is a glass lens. Plastic lenses have temperature characteristics featuring a decrease in refractive index with rising temperature, while the glass lenses have temperature characteristics featuring an increase in refractive index with rising temperature. A maximum value α of a tangent angle of the image-side surface of the first lens satisfies; 45°≤α≤70°...(1).SELECTED DRAWING: Figure 1 |
