Due to the actual situation, I had some sparetime for testing:
I recorded short clips of me using a slate over quite some time. Sound got recorded internally as well as to the zoom f8. As I can not tell for sure which one of these devices, if not both do drift, in the following graphs only the measured difference in ms (offset) between them is displayed. Both test were done twice with the same results (within common error range). Framerates were both set to 25, samplerate set to 48000Hz.
1. I took the zoom f8 as a master connected to the bmpcc4k via cable. No adapters needed, cable working fine, external sync indicated. See the repetitive pattern:
- Timecode test 1
- timcodetest-1.jpg (72.93 KiB) Viewed 1759 times
The maximum variance is 18ms, max difference about 25ms (~ 1/2 of a frame), visually both stay in sync with the picture. Visually I couldn't tell which one would be more accurate, slight echoes were audible.
2. I just jam synced the bmpcc4k from the zoom f8, than removed the cable. Beforehand both internal clocks (rtc) were set to the clock of my computer by cable, too:
- timecode 2
- timecode 2.jpg (32.96 KiB) Viewed 1759 times
Although they were instantly off by two frames, the maximum variance is only 6ms within the given time! I know, it was not that long of a period. Audio and video was visually off, of course.
So, what to do with these informations? Both stay in sync reasonably, although one with a more or less constant offset of two frames within the given time. But still, it is not the result I had expected. I expected a drift more smoothly over time, not with any jumps like above.
- Is the timecode clock from the f8 not stable enough?
- Is it a problem of the camera getting warmer over time?
- Is it a problem of missing genlock and two clocks (shutter and audio) running at different speed/pulses?
I still have to wait for the Nanolockits to arrive to compare, but will do so.
I'm curious about your opinions.