Did you set all 3 cameras for manual control of exposure?
I saw this about your camera:
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Please note that there was a version of Logitech's driver software that didn't allow for manual control of exposure for more than 2 cameras connected at a time. There was an update that fixed this.
Without this manual control, your frame rates can vary based on how bright/dark something is, so you definitely want to set up the software for manual control for all four cameras.
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Please post your results, success or failure. I notice a ' lightdog' was able to get it working with 4 of your cameras
viewtopic.php?f=7&t=29- and I'm very interested in ordering some cameras and testing. My guess is you won't hear any responses from them until after SIGGRAPH.