Built for endurance as well as speed, the shutter unit is specially designed to match the EOS-1D Mark III’s APS-H-size CMOS sensor. The new high-torque shutter mechanism has the highest durability of the Canon lineup with a seemingly inexhaustible 300,000 cycles, attaining speeds of up to 1/8000 sec. Performance is further enhanced by a short shutter release time lag of 55ms and a viewfinder blackout time of only 80ms. The X-sync function has an optically detected, contactless switch for robust and reliable use with Speedlites, and now has an increased maximum flash sync speed of 1/300 sec*. For utterly clean and consistent performance, the unit also has been enhanced to reduce dust. *When using an EX-series Speedlite.