Hello, I have a SBIG STX-16803 camera (firmware version 2.45) and I am trying to use the trigger out signal from the I2C port. According to the old SBIG document "Trigger Signals on the USB Cameras" that I found over the internet the trigger out pin number is 7. That seems to be correct. According to the same document the pin state should go low when shutter if fully open and go high when shutter starts to close. That does not seems to be true. I connected the camera to a special device that is using GPS to precisely measure time of every change of state on camera's pin 7. When I set exposure time to 0.18 sec I am getting for example that pin 7 is going low at some moment of time and stays low for 0.47 sec. As far as I understand it should be low for only 0.18 sec, because the shutter was definitely not fully open for 0.47 sec. The same happens when I set longer exposure time. Pin 7 always stays low for 0.29 sec longer than exposure time selected in camera software (I am using CCDOps). What am I missing? Is the trigger out signal working as described in that old document? Perhaps in newer cameras it includes also the time of shutter partially open? My goal is to have a very precise shutter timing of +/- 0.01 sec or better for satellite tracking observations. An error of 0.29 sec is far too much for such a project.
