 This meant that the system was independent of ambient light levels and achieved a high degree of accuracy; however, it could be fooled by glass (which is not transparent to infrared radiation).The autofocus area was marked on the reverse-Galilean optical viewfinder, which also had projected framelines, zone focusing marks for near, medium and far (lit to indicate the approximate area the autofocus had selected), parallax correction marks, and battery-check and camera-shake warning LEDs.Viewfinder magnification was 0.5× and coverage was 85% of the full 135 frame area.