Nikon GP-1 mounted on a D90We as photographers have a lot to think about when going out on a complex multi-camera shoot. Between getting all (and I mean all) the gear ready for that specific job, batteries fully charged up, enough memory cards pre-formatted (never format a card on the job, but that is the topic of another post), details of the job, enough sleep before, and sufficient caffeine during....well you know the drill. You get to the job and meet the other photographers, each shooting their own set of gear from all walks of life. You barely have time enough for hellos and to hand out assignments, and coverage duties, and you are all off, some shooting and some meeting with the clients (doing the schmooze). Oops, forgot the time-sync the cameras.

For anyone who shoots multiple camera jobs (even if it is just you and 2 cameras), it is a nightmare in post production if the cameras are not time-synced. Why? Because the edit is usually accomplished best and fastest if the pictures are in chronological order. If the cameras are not time synced (their clocks set to identical times) then the pictures will be somewheres between "grouped by camera" (based on their very different time settings) to intertwined in a global mess (if their clock settings were off by smaller increments of time). It is much better if the clocks on non synced multiple cameras were more than n  (with n being the length of the shoot + 1 second). That gives you the group by camera effect. If the clocks are only seconds apart (more likely), then the post production person has many scenes from the job with the shots from the different cameras interspersed and the events appearing to be in some weird and random order.

Of course this all assumes that the different cameras are shooting the same scene, and not 2 different scenes at the same time. In the latter case, one has to take on a different strategy of sorting the files first by camera or photographer, and then chronologically.

How to time sync multiple cameras

• Have everyone get together in a giant circle, check your cell phone for the proper time (exact time is not crucial in this method), and all hit the SET button at the same time (maybe someone could yell out "set!"). Not a bad method. It is accurate to within a second or so, but is somewhat hard to do if anyone has more than one camera to set. Also subject to user error. Like forgetting to also set the correct day.
• Pass around a cell phone (or digital watch), and have everyone set their own cameras to the reference time. Not bad, but takes a lot of time, and subject to user error.
• Have everyone take a shot of the same very recognizable subject at the exact same moment (someone could yell "click!). Does not set the clock, but creates a slate sync (like a clap stick on a movie set) such that all of the files from all of the cameras can be time-slipped in post production based on the sync frame from each camera. Very quick on the job and a good thing to do even if you have set the clocks, but a lot of work in post.

or, use the high tech magic bullet

If each camera is equipped with a GPS system, a common (international) time base is applied to the EXIF data of all captures, and without intervention or remembering to set the clock, any number of cameras can be time-synced together. In fact once all camera have GPS on-board (not too far away), there will be no more need to set the clock because the time will be derived from the GPS satellite signal. The clock is set by the GPS magician who live on the International Time Line.

What triggered this post was Nikon's announcement of its new GP-1 GPS adapter which can be used on most any of its recent digital cameras. Below are the details courtesy of Imaging-Resource.

The Nikon GP-1 is a little gadget that mounts on the hot shoe, and plugs into a new, dedicated GPS port on the side of the camera, using the GP1-CA90 accessory terminal cord. (While it's being announced with the D90, the GP-1 can also be used with the D3, D300, D700, D2x, D2xs, D2Hs, and D200 by plugging it into the 10-pin accessory terminal on those cameras, using the GP1-CA10 accessory terminal cord.) We haven't yet seen a sample of the GP-1, but it sounds relatively compact, at 1.97 x 1.79 x 1.00 inches (50 x 45.5 x 25.5mm). Power comes from the camera body, but we don't yet know how big an effect it will have on camera battery life. When operating, the GP-1 will copy latitude, longitude, altitude and time data into the EXIF headers of any image files captured. At this point, we have very little information on the GP-1 (including its projected price in the US), but one spec caught our eye: The GP-1 on average requires only 35 seconds for satellite acquisition, only 5 seconds from a hot start. That "hot start" seems tied to a setting on the setup menu for the GPS: You can apparently set it up to power-down whenever the camera's exposure meter shuts off. This could potentially save a lot of battery power, but at the relatively minor cost of needing to wait 5 seconds before snapping a shot after activating the camera's exposure meter, for the GPS unit to wake up. An interesting accessory, one we think will find a lot of application in various commercial, insurance, and governmental settings, where photos need to be authoritatively tagged with specific location information.