Why is TOD timecode used by sound? Why do they JAM SYNC TOD timecode from sound recorder to slate? How often should we Jam sync?

TOD is the easiest way to insure that everyone on the set has access to the current timecode (such as Script Supervisors, AC's, etc.) All they have to do is glance down at their watch! It also makes it idiot simple to see if the slate, recorder, or camera has lost its timecode sync. In the event of an electronic glitch, the numbers displayed will almost never be off by a hair or two... instead the displayed timecode will be grossly off by a lot of hours and minutes. TOD also provides an easy way to sort takes by date/time.

In addition to the TOD timecode settings (watch time), you MUST ALSO set the USER BITS. I suggest that the first four digits of your user bits represent the month and date (example 0318 for Mar 18). That metadata will help you sort all the takes by date, and also insure that you do not repeat the same timecode on two different days (since tc will repeat every 24 hours). But if the User Bits are changed at least once per day, then the complete timecode data will always be unique. The last four digits of the user bits, I like to use as a reference to the camera media (hard drive number, or P2 card number, etc.) Again, this provides redundant metadata for Post to use in tracking the dailies.

The audio recorder is always the Master timecode, and everything else syncs from it. Begin by syncing the Denecke slate to the recorder. Then, the slate itself becomes a portable TC generator, and can be used to sync the camera to the slate, or multiple cameras to the slate. recorder>slate>camera is the sequence. That workflow insures the least chance of errors, since the slate and recorder are always visually the same; even if the internal TC of the camera may be different for whatever technical reasons. The photographed images of the slate will show the TOD timecode, and then a brief image of the Users Bits. That will always provide an editorial idiot proof sync point.

Although you can jam just once every 5 or 6 hours, it is always best practice to jam as often as possible, such as every couple of hours. Take advantage of camera downtime. Note that the master timecode on the recorder is not changing when you jam, so you are really just updating the slate to insure accuracy. However, anytime that you make manual changes to the User Bits (a new date, or a new camera media drive/card) then you MUST re-jam the slate for that change to take effect.