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

Claim 9:
10. 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,
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), (6) and (16) are satisfied:

−7.1f2/f<−2.5  (2a)

1.0<|f23|/f<4.5  (6)

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,
f23: a composite focal length of the second lens and the third lens, and
f34: a composite focal length of the third lens and the fourth lens.