user6291: I am trying to get 2 video streams into sync at low cost. I would like to visually measure how good can I synchronize my cameras by pointing them to a millisecond capable stopwatch.
Does anyone know what is the refresh rate of an "old style" monochromatic LCD stopwatch (example)? I don't have one so I haven't tried to capture these yet. Wikipedia says an LCD could have a refresh rate as high as 200Hz. If LCD is slow, LED probably would be faster depending on circuity used.
So far I used online stopwatch, but these are limited by (usually) a 60Hz refresh rate of a computer LCD monitor. 60Hz lowers the resolution to about 16ms (1s/60Hz).

user3908: You can only sync video to an accuracy of a frame, or somewhere in the area of 15-40 mSec depending on frame rate. So as long as whatever you're shooting can update and refresh at least that quickly, it's not important to do much better. Even shooting a mechanical metronome will probably get you as close as anything else. The refresh rate of the display shouldn't be a factor, if you're examining both clips on the same screen.

6291: <p>I am trying to get <a href="https://video.stackexchange.com/questions/12312/creating-synchronized-stereo-videos-with-2-cameras-at-low-cost">2 video streams into sync</a> at low cost. I would like to visually measure how good can I synchronize my cameras by pointing them to a millisecond capable stopwatch.</p>

<p>Does anyone know what is the refresh rate of an "old style" monochromatic LCD stopwatch (<a href="https://commons.wikimedia.org/wiki/File:Leet_stopwatch.JPG" rel="nofollow noreferrer">example</a>)? I don't have one so I haven't tried to capture these yet. <a href="https://en.wikipedia.org/wiki/Liquid-crystal_display" rel="nofollow noreferrer">Wikipedia says</a> an LCD could have a refresh rate as high as 200Hz. If LCD is slow, <a href="https://commons.wikimedia.org/wiki/File:LED_Digital_Display.jpg" rel="nofollow noreferrer">LED</a> probably would be faster depending on circuity used.</p>

<p>So far I used online stopwatch, but these are limited by (usually) a 60Hz refresh rate of a computer LCD monitor. 60Hz lowers the resolution to about 16ms (1s/60Hz).</p>
 3908: <p>You can only sync video to an accuracy of a frame, or somewhere in the area of 15-40 mSec depending on frame rate. So as long as whatever you're shooting can update and refresh at least that quickly, it's not important to do much better. Even shooting a mechanical metronome will probably get you as close as anything else. The refresh rate of the display shouldn't be a factor, if you're examining both clips on the same screen.</p>
