Lens optical system
View Patent ↗A wide-angle lens optical system, including, in a sequence from an object side, a first lens group having a positive or negative refractive power, a stop, and a second lens group having positive refractive power, wherein the first lens group comprises, in a sequence from the object side, a front group having negative refractive power and a rear group having positive refractive power, and the wide-angle lens optical system satisfies the following Inequalities: 1.0 < f II f < 1.45 0.6 ≤ f Ia f Ib < 1.5 where f denotes the overall focal distance of the lens optical system, f II denotes the focal distance of the second lens group, f Ia denotes the focal distance of the front group of the first lens group, and f Ib denotes the focal distance of the rear group of the first lens group.
1. A lens optical system comprising, in a sequence from an object side:
a first lens group;
an aperture stop; and
a second lens group having positive refractive power,
wherein the first lens group comprises, in a sequence from the object side, a front group having negative refractive power and a rear group having positive refractive power, and the lens optical system satisfies the following Inequalities:
1.0
<
f
II
f
<
1.45
0.6
≤
f
Ia
f
Ib
<
1.5
where f denotes the overall focal distance of the lens optical system, f II denotes the focal distance of the second lens group, f Ia denotes the focal distance of the front group of the first lens group, and f Ib denotes the focal distance of the rear group of the first lens group.
2. The lens optical system of claim 1 , wherein the front group of the first lens group comprises at least one positive lens and the lens optical system satisfies the following Inequalities:
1.80 <nIa ( p )
vIa ( p )<35
where nIa(p) denotes the average refractive index value of the at least one positive lens of the front group of the first lens group, and vIa(p) denotes the average dispersion value of the at least one positive lens of the front group of the first lens group.
3. The lens optical system of claim 1 , wherein the first and second lens groups are moved to perform focusing.
4. The lens optical system of claim 1 , wherein the front group of the first lens group comprises, in a sequence from the object side, at least one meniscus type negative lens having a convex surface on the object side and a positive lens with both surfaces convex.
5. The lens optical system of claim 1 , wherein the rear group of the first lens group comprises two strong positive lenses and a negative lens.
6. The lens optical system of claim 1 , wherein the second lens group comprises a negative lens and three positive lenses.
7. The lens optical system of claim 1 , wherein the second lens group comprises:
a doublet lens comprising a meniscus negative lens having a concave surface on the object side and a meniscus positive lens having a convex surface on the image side; and
two meniscus positive lenses having convex surfaces on the image side.