Stereoscopic optical system and image pickup apparatus

An image pickup apparatus comprising:

• a stereoscopic optical system comprising two optical systems arranged in parallel;
• and
• an image sensor configured to image optical images formed by the two optical systems,
• wherein each of the two optical systems includes, in order from an object side to an image side, a front unit having a negative refractive power, an intermediate unit having two reflective surfaces, and a rear unit,
• wherein a distance between optical axes of rear units is smaller than a distance between optical axes of front units in the two optical systems due to bending of an optical path by the two reflective surfaces,
• wherein at least one of the intermediate unit and the rear unit has a positive refractive power,
• wherein the front unit includes, in order from the object side to the image side, a first subunit consisting of one or more negative lenses disposed on the object side of a positive lens closest to an object in the front unit, and a second subunit having a positive power, and
• wherein the following inequalities are satisfied:
• 0.20≤f1A/f1≤0.42;
• and
• 0.61≤|f3/f2|≤0.90;
• where f1, 12, f3, and f1 A are focal lengths of the front unit, the intermediate unit, the rear unit, and the first subunit for d-line, respectively.