Leon Benzakein wrote:I would appreciate a clearing up of a definition of the term "jam sync".
Any time you connect an external TC clock to an Ursa Mini or Ursa Mini Pro, if the format is correct and the camera sees the external TC source the letters 'EXT" will appear in the top middle where the TC numbers are on the screen. You can toggle between clip TC and TOD TC here too by simply tapping the TC number.
As soon as the external TC source isn't connected, the letters "INT" will appear, showing you're running from the internal clock of the camera.
Leon Benzakein wrote:I know it to be that of using an external device with master time code being attached to a camera etc temporarily to sync that device to master time.(free run)
Free run time of day yes...
Now an aside....
You say "master" time code, but be careful with terminology.
Ideally you have a standalone master TC clock. This master clock can then jam sync other clocks. The other clocks MIGHT be another external stand-alone clock that you then put on your camera OR it might be the camera itself OR it might be the location sound recorder OR it might be a TC slate.
Some cheat and use a clock from say, the recording device itself to be the "master" clock.
This can be more risky, but is more or less common. Who wants to pay extra for a standalone clock right ? In my view, a true "master" clock is one that can TELL you the time difference between it's own clock and that of which you're jamming to. This helps greatly in troubleshooting.
For example you can plug an external TC clock into the master TC clock and it will tell you how much of a time difference the two clocks have. Or you can feed the TC output of a camera and it will tel you if the internal clock of that camera has drifted or is offset. If you DON"T use a clock like this and just re-jam everything, you never get to know what the TC drift or offsets are and it's harder to troubleshoot when things aren't working.
Here's an example of a true "master clock"
https://www.bhphotovideo.com/bnh/contro ... sku=427929Leon Benzakein wrote:The master time code device is then removed and the camera etc runs on its internal time code generator.
That is only ONE way you can set this up. What I was saying earlier, is that I generally don't trust ANY camera internal clock, so I leave a jammed TC external clock plugged into the camera FULL TIME so that it constantly re-jams the internal clock as long as it's connected.
Here's an example of a slave TC clock
http://ambient.de/en/product/nanolockit/Leon Benzakein wrote:If the internal time code generator is unreliable this method is unreliable.
It very often is, even on cameras that are said to be reliable. Alexa are pretty good for example (Ambient make their internal TC clocks), but you can still go wrong when you change the frame rate and shoot slow motion and then go back, or if you power down the camera for too long on a battery change.
This is why the full time external dedicated TC clock is considered the more correct and safer practice, though few but the more resourced productions practice this.
Leon Benzakein wrote:My confusion comes from some of the posts on this topic which mention jam sync but I am not sure if the posters are talking about a hardwired time code feed/external T/C generator or temporary sync feed.
It's often because people talk of jamming a camera. Unspoken is whether they are jamming it and taking away the master TC clock or using an external slave TC clock to jam and taking that away, or if they are leaving an external TC clock connected full time to continuously re-jam the internal clock.
It's 2017 and you would think sync should be a no brainer but there is still so much confusion about acceptable TC practices and the best way to go.
JB