I have MaxIm DL Pro 6 (just upgraded to 6.20) controlling a QSI 583 WSG CCD camera. Using the QSI plugin for MaxIm I run Bias exposures and from the Info display they look to be 0.000 second exposures. I'm moving to use the QSI ASCOM driver and connect MaxIm DL to the ASCOM driver and select the QSI camera driver in the driver picker. When I attempt to take a Bias exposure I get an ASCOM driver error reported - "Error starting exposure Could not invoke 'StartExposure' Reason: Exception occurred. QSICamera.CCDCamera.1: Invalid Exposure Duration" The minimum mechanical shutter speed on the QSI camera is 0.03 seconds. I can run Dark frame exposures down to 0.031 seconds, at 0.03 seconds and below I get the same error. For Bias and Dark frames I would think the shutter would be kept closed, so you shouldn't restrict the exposure duration to 0.03 e.g. StartExposure (Duration = 0.0, Light = False) ? How does MaxIm DL take Bias frames when connected to an ASCOM camera driver?