Image sensor and image capturing apparatus

An image capturing apparatus comprising an image sensor including a plurality of image forming pixels which detect an object image formed by an imaging optical system and generate a captured image, and a lens which is arranged for the plurality of image forming pixels and converges incident light to the image forming pixels,

• wherein each of the image forming pixels includes a plurality of divided photo-electric conversion units,
• the plurality of photo-electric conversion units have a function of photo-electrically converting a plurality of images having passed through different exit pupils of the imaging optical system, and outputting focus detection signals for performing focus adjustment by a phase-difference detection method,
• each of the image forming pixels includes a first light guide and a second light guide between the lens and the plurality of divided photo-electric conversion units,
• the first light guide is arranged on a side of the lens, and the second light guide is arranged on a side of the photo-electric conversion unit, and
• a division count of the second light guide is larger than the division count of the first light guide.