Operating a camera in the control mode lets you program both the delay time and the exposure time at the frame grabber. This mode gives you the most control over acquired images. In the control mode, the frame grabber's exposure signal resynchronizes the camera and the width of the exposure signal determines the exposure time. Note that the camera may introduce a short delay between the end of the exposure signal and the start of the video signal. This delay is preset in the camera and cannot be adjusted.
Delays are typically a few hundred milliseconds.
You can take advantage of the control mode to adjust the exposure in your application. You may wonder why you might need this capability. Bulb intensity can change with time, so you'll need to adjust the exposure time to compensate for changing light levels. Also, some parts of objects have different reflective properties. For example, the black body of an IC reflects little light while the shiny leads reflect a lot of light.