I just measured the time accuracy of my newly purchased GP-E1. The advertised accuracy as shown on the Canon USA website is +/- .01 sec. I installed an NTP time app on my iPhone (Emerald Time), which claims a corrected time to the nearest tenth of a second. (I verified Emerald Time's accuracy by calling the NIST time recording at 303-499-7111.) Below is a photo of Emerald Time and the associated exif time data. The GP-E1 was more than a second off. I force-updated the camera's clock off the GPS multiple times and the results were consistent and repeatable.