An optical pickup capable of focusing a main light spot and an auxiliary light spot including optical aberration when an optical disk is not tilted, and analyzing the main light spot and the auxiliary light spot with a photodetector, thereby correcting aberration. The 256 QAM modulator outputs 256 QAM points to a summer. More particularly, this invention relates to a pitching practice device having a strike zone indicator that can be conveniently adjusted to simulate the strike zones of batters of various heights.