Three-dimensional image pickup optical system and three-dimensional image pickup apparatus
A three-dimensional image pickup optical system for forming two different images having a parallax alternately in time sequence on a single image pickup element, includes, in order from object side: a front system including a pair of negative 1f-lens units, a pair of an optical path deflecting units, and a combining unit for combining two optical paths on the same optical axis; and a rear system including a positive 1b-lens unit which does not move for magnification-varying, a lens unit moving for magnification-varying, and a stop, in which: the front system includes a pair of light quantity control units disposed in optical paths for the eyes on the object side of the combining unit, for switching left and right subject images alternately in a time sharing manner; and power arrangement of the 1f-lens units and the 1b-lens unit is set appropriately.
1. A three-dimensional image pickup optical system for forming two different images having a parallax for left and right eyes alternately in time sequence on a single image pickup element, the three-dimensional image pickup optical system comprising, in order from an object side:
a front optical system including a pair of 1f-lens units each having a negative refractive power, a pair of optical path deflecting units, and an optical path combining unit for combining two optical paths on the same optical axis; and
a rear optical system including a 1b-lens unit having a positive refractive power which does not move for magnification-varying, a lens unit which moves for the magnification-varying, and a stop,
wherein the front optical system includes a pair of light quantity control units, which are disposed in the optical paths for the left and right eyes on the object side of the optical path combining unit, for switching left and right subject images alternately in a time sharing manner, and
wherein the following conditions are satisfied:
−10.0 <f 1 f/fw<− 1.5; and
0.9 <f 1 b/ft< 5.0,
where f1f denotes a focal length of the 1f-lens unit, f1b denotes a focal length of the 1b-lens unit, fw denotes a focal length at a wide angle end of the three-dimensional image pickup optical system, and ft denotes a focal length at a telephoto end of the three-dimensional image pickup optical system.
2. A three-dimensional image pickup optical system according to claim 1 , wherein the front optical system further includes a 2f-lens unit having a positive refractive power between each of the pair of optical path deflecting units and the optical path combining unit.
3. A three-dimensional image pickup optical system according to claim 1 , wherein the rear optical system includes the 1b-lens unit having the positive refractive power which does not move for the magnification-varying, a 2b-lens unit having a negative refractive power which moves for the magnification-varying, a 3b-lens unit for image plane correction, the stop, and a 4b-lens unit having a positive refractive power which does not move for the magnification-varying.
4. A three-dimensional image pickup optical system according to claim 3 , wherein, in the rear optical system, the following conditional expression is satisfied:
0.15 <βvw×βcw×βrw< 0.60,
where βvw denotes an imaging magnification of the 2b-lens unit at the wide angle end and an infinite object distance, βcw denotes an imaging magnification of the 3b-lens unit at the wide angle end and the infinite object distance, and βrw denotes an imaging magnification of the 4b-lens unit at the wide angle end and the infinite object distance.
5. A three-dimensional image pickup apparatus, comprising:
an image pickup element; and
the three-dimensional image pickup optical system according to claim 1 for guiding light from an object to the image pickup element.