I'm trying to add a "focus mode" to my custom SBIG camera control software, which has otherwise been working successfully for many years. I am testing with an SBIG ST8-XE detector and the SBIG Universal Driver Library Ver 4.68 Build 4, dated Dec 23, 2010. The limiting factor for taking multiple integrations in quick succession seems to be the CC_START_EXPOSURE command which, regardless of the duration of the integration, requires 0.70 +/- 0.06 s to start an exposure. In an attempt to improve performance, I explicitly open the shutter first and specify the "leave shutter alone" option when starting each exposure, and also set the flags START_SKIP_VDD and START_MOTOR_ALWAYS_ON. I have also set the SetDriverControlParams parameter DCP_HIGH_THROUGHPUT flag to TRUE prior to commencing the sequence of integrations. Are there any other options I can use to decrease the time taken to start an exposure?