CPC G02B 13/0045 (2013.01) [G02B 9/64 (2013.01)] | 19 Claims |
1. An imaging lens comprising in order from an object side to an image side,
a first lens having positive refractive power,
a second lens,
a third lens,
a fourth lens having negative refractive power,
a fifth lens having positive refractive power,
a sixth lens, and
a seventh lens, wherein said fourth lens has a convex surface facing the image side near the optical axis, and the following conditional expressions (2a), (3), (13) and (16) are satisfied:
−7.1<f2/f<−2.5 (2a)
0.3<t2/t3<3.3 (3)
50<νd7<60 (13)
2.5<|f34|/f<12.0 (16)
where
f: a focal length of the overall optical system,
f2: a focal length of the second lens,
f34: a composite focal length of the third lens and the fourth lens,
t2: a distance along the optical axis from an image-side surface of the second lens to an object- side surface of the third lens,
t3: a distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, and
vd7: an abbe number at d-ray of the seventh lens.
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