Precise camera feedback - duplicate entries


I made a feedback cable for Canon point and shoot cameras that uses a phototransistor instead of a hot shoe. I’m able to flash the red eye LED when the shutter opens. However, it stays on for ~ .4 seconds. This sends a high state to the Pixhawk for that long. Sometimes I get good results, other times I get duplicate CAM events. I read somewhere there was talk of just picking up the rise? I think the duration is my problem. Any ideas how to avoid duplicates? Here’s a sample from my log:

Hi, Brian

Have you solved this issue? I’m under similar problem too…