Patent ID: 11874433
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 having negative refractive power,
a fifth lens having positive refractive power,
a sixth lens, and
a seventh lens, wherein said second lens has a convex surface facing the object side near the optical axis, said fourth lens has a convex surface facing the image side near the optical axis, and the following conditional expression (2a) and (16) are satisfied:

−7.1<f2/f<−2.0  (2a)

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