California Code, Elections Code - ELEC § 15627

(b)(1) If the recount is to be conducted manually and the voting system has the capability to display ballot images, the voter requesting the recount shall select whether the recount shall be conducted by use of paper ballots or the official ballot images.

(2) If more than one voter requests that a recount be conducted manually for the same office or measure, and at least one request is for the recount to be conducted by use of paper ballots, the county elections official of a county subject to multiple requests as described in this subdivision shall conduct only a manual recount of the paper ballots, the result of which shall be controlling.