Author Options:

Anyone know of a cheap Digital Video-Camera that has (or can be hacked to support) External / Asynchronous triggering? Answered

Basically, I'm wanting to record something from several vantage-points (tennis-strokes mostly, but it would be relevant for things such as baseball or golf swings as well) using two or more cameras.

The problem of recording with multiple-cameras is, if they're not triggered simultaneously, they could be capturing their respective frames at as much as 1/(fps*2) of a second (i.e.;16.7 ms for 30 fps) off from one another; which for many, if not most things wouldn't be a concern. However, since they wouldn't capturing the event at the exact-same moment, the usability of the video information for motion-analysis purposes is greatly reduced.

For everything else other than lacking support of external/async. triggering, something like my relatively-cheap $120 ApiTek 60-FPS 1080p Camera (Std-Def would suffice) I picked-up on a whim at Walgreen's would fit the bill quite nicely.

While professional cameras do have this feature (also referred to as a Master/Slave Camera Array), this is simply for my personal-use, and I'd have a hard time selling my wife on the idea that I need to spend multiple thousands of dollars on it.


Jack A Lopez

8 years ago

Wow! So you want a plurality of video cameras, all capturing frames in phase with one another?  All cameras "snapping" at the same instant?

I have no idea how to do this...  However, if you can figure out what chips are in your "relatively-cheap" camera, and then look up the data sheets for those chips, and then figure out if there is a specific pin where the strobe, or timing signal goes, and then come up with some way to get all of those pins (one for each camera) feeding off the same timing signal...  I'm not sure how much physical distance there is between each camera.  I mean for wires that are too long you may have problems with noise, maybe...

Anyway, this is all  just a wild guess. 


8 years ago

If you have professional cameras, you can gen-lock them, but from your description I assume you're just using consumer camcorders.  If possible, I suggest using a clapboard each time you need to sync the cameras.  The most you can possibly be off using 29.97 is a single frame, which is barely discernible to the eye anyway.  I've never done slo-mo stuff with tennis, but can attest that it works fine with boxing, and more relative to your sport it also works for baseball.  I understand why you want it to be exact, but if you give it a try I think you'll be pleasantly surprised.

Another alternative which I haven't tested- If you use all one brand, say Sony Handycams, which operate via remote, you could in theory use one remote to start all of your cameras at once.  Would it be frame accurate?  I'm not sure.