This thesis project was undertaken with the intent to discover the source of a known but hitherto unexplained error in the calibration of the wings for a haploscope used in depth perception studies. The angles of the haploscope wings are used to control the vergence angle of the virtual images projected into each eye. This accounts for a strong depth cue used in AR and depth perception studies. Two experiments were devised to both display and attempt to characterize the error between the theoretical wing angles needed to cause a user's vision to verge at some focal depth and the actual wing angles that caused vergence. The investigation revealed a near-constant offset between the theoretical and actual angles needed. This suggests that the error may not stem from the haploscope alignment itself, but from how the center of the user's eye is currently modelled.