An objective includes a first lens group that has a positive refractive power and a second lens group that has a negative refractive power. The objective includes a first negative lens and satisfies
0.005d.sub.o1/h.sub.o10.1(1)
0.005h.sub.min/h.sub.l0.72(2)
10 mmL100 mm(3)
0.1L/f31(4)
when d.sub.o1 is a thickness of the first negative lens, h.sub.o1 is an axial marginal ray height on a lens surface on the object side of the first negative lens, h.sub.min is a minimum value of an axial marginal ray height in the second lens group, h.sub.l is a height of an axial marginal ray on a lens surface of the objective that is situated closest to the image side, L is a length of the objective, and f is a focal length of the objective.

An endoscope objective optical system consists of in order from an object side, a front group having a negative refractive power, an aperture stop, and a rear group having a positive refractive power, wherein either the front group or the rear group includes one or more than one cemented lens, and the cemented lens includes a lens having a positive refractive power and a lens having a negative refractive power, and the rear group includes a positive lens which is a single lens, on the object side, and the following conditional expressions (1), (2), (3), and (4) are satisfied.

1.1<Ih/ft<1.8(1)

ff/ft<0.9(2)

45<d1(3)

LOs/Ih<1.5(4) where, Ih denotes the maximum image height, ft denotes a focal length of an overall endoscope objective optical system, ff denotes a focal length of the front group, d1 denotes Abbe's number for a glass material of the lens having a positive refractive power, on the object side of the rear group, and LOs denotes a distance from a first surface on the object side of the endoscope objective optical system up to the aperture stop, and here the first surface on the object side of the endoscope objective optical system is a lens surface positioned nearest to object in the endoscope objective optical system.

A single focus lens and a photographing apparatus including the single focus lens are provided. The photographing apparatus includes a single focus lens comprising: a first lens group having a positive refractive power, the first lens group including a first negative lens and a second negative lens arranged in succession at a most object side of the first lens group; a second lens group having a negative refractive power; and a third lens group having a positive refractive power and including a positive lens and a negative lens. The first to third lens groups are sequentially arranged in a direction from an object side to an image side.

A single focus lens and a photographing apparatus including the single focus lens are provided. The photographing apparatus includes a single focus lens comprising: a first lens group having a positive refractive power, the first lens group including a first negative lens and a second negative lens arranged in succession at a most object side of the first lens group; a second lens group having a negative refractive power; and a third lens group having a positive refractive power and including a positive lens and a negative lens. The first to third lens groups are sequentially arranged in a direction from an object side to an image side.

An objective includes a first lens group that has a positive refractive power and a second lens group that has a negative refractive power. The objective includes a first negative lens and satisfies

0.005d.sub.ol/h.sub.ol0.1 (1)

0.005h.sub.min/h.sub.l0.72 (2)

10 mmL100 mm (3)

0.1L/f31 (4)

when d.sub.o1is a thickness of the first negative lens, h.sub.o1 is an axial marginal ray height on a lens surface on the object side of the first negative lens, h.sub.min is a minimum value of an axial marginal ray height in the second lens group, h.sub.l is a height of an axial marginal ray on a lens surface of the objective that is situated closest to the image side, L is a length of the objective, and f is a focal length of the objective.

An objective includes a first lens group that has a positive refractive power and a second lens group that has a negative refractive power. The objective includes a first negative lens and satisfies

0.005d.sub.ol/h.sub.ol0.1 (1)

0.005h.sub.min/h.sub.l0.72 (2)

10 mmL100 mm (3)

0.1L/f31 (4)

when d.sub.o1is a thickness of the first negative lens, h.sub.o1 is an axial marginal ray height on a lens surface on the object side of the first negative lens, h.sub.min is a minimum value of an axial marginal ray height in the second lens group, h.sub.l is a height of an axial marginal ray on a lens surface of the objective that is situated closest to the image side, L is a length of the objective, and f is a focal length of the objective.

An image pickup apparatus includes an optical system including a first substrate and a first optical element having refractive power disposed on the first substrate, and a light receiving element having a light receiving surface on which an image is formed by the optical system. A predetermined inequality is satisfied.

An image pickup apparatus includes an optical system including a first substrate and a first optical element having refractive power disposed on the first substrate, and a light receiving element having a light receiving surface on which an image is formed by the optical system. A predetermined inequality is satisfied.

A single focus lens and a photographing apparatus including the single focus lens are provided. The photographing apparatus includes a single focus lens comprising: a first lens group having a positive refractive power, the first lens group including a first negative lens and a second negative lens arranged in succession at a most object side of the first lens group; a second lens group having a negative refractive power; and a third lens group having a positive refractive power and including a positive lens and a negative lens. The first to third lens groups are sequentially arranged in a direction from an object side to an image side.

A single focus lens and a photographing apparatus including the single focus lens are provided. The photographing apparatus includes a single focus lens comprising: a first lens group having a positive refractive power, the first lens group including a first negative lens and a second negative lens arranged in succession at a most object side of the first lens group; a second lens group having a negative refractive power; and a third lens group having a positive refractive power and including a positive lens and a negative lens. The first to third lens groups are sequentially arranged in a direction from an object side to an image side.