Patent ID: 11899174
Assignee: TOKYO VISIONARY OPTICS CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An imaging lens comprising in order from an object side to an
image side,
a first lens,
a second lens,
a third lens,
a fourth lens,
a fifth lens having positive refractive power,
a sixth lens having positive refractive power, 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), (16) and (18) are satisfied:

−7.1f2/f<−2.5  (2a)

2.5<|f34|/f<12.0  (16)

0.1<r1/r2<0.7  (18)

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,
r1: a paraxial curvature radius of an object-side surface of the first lens, and
r2: a paraxial curvature radius of an image-side surface of the first lens.