Running two cameras in sync?

[KarelBata]

Asked for this in the Vimeo forum, but it's worth keeping it going.

Sync-ing two cameras would be SO good for us working in 3D. It would cause a revolution. Seriously. We're currently stuck with huge cameras, or small ones with poor image quality. To be able to use a pair of DSLRs would be a game-changer.

I know there's several claims to be able to do it, but they don't really work. If they did, we'd all be doing it. 

The kind of level of sync needed for good 3D is shown here:



This was using a pair of Canon 105s that allow genlock (but Canon didn't say how in the manual!  )


Cheers! 

[lexa_one]

It work with an IR remote (test with 550D/600D)

[scrax]

Good to know,
waiting the universal remote support  (and another camera btw)

[softimage69]

This would not be a production bullet proof solution by any means, but it should allow pictures and videos to start and stop at the same time.  Buy two sets of RF remotes (like the Yong Nuo RF-603 I have with my 60D). 

You can set the frequency the same to each of these sets, which should capture pics and start/stop video in sync with one another.  I cannot attest to any micro-second accuracy or lag that may occur, but this is a somewhat cheap / fun way to at least test out. 

Worst thing is though, you need to change the settings on both cameras everytime you change anything like Aperture, Shutter Speed, ISO, etc.  This is where having a software writer / electrical engineer at your disposal would come in handy to make an interface / computer software to sync them with proper accuracy.

Just my two cents....

[Malcolm Debono]

I'm not sure how accurate a wireless remote is. I couldn't test it well since my cameras are different (5D2 and 60D), but when I tried it there was an offset between the start of the recordings, and this changed every time I tried it. This is quite a small amount of time, but you still won't get a perfect sync.

Maybe someone who has 2 same bodies and a wireless remote can try this out and tell us how it goes 

[Leon]

If you just need to start and stop recording on two cameras at the same time, MagicLantern already lets you do that!

You just need to connect the two shutter release sockets together directly using a standard stereo 2.5mm jack to 2.5mm stereo jack cable.  They're less than £2 / 2 Euros including delivery (eg Amazon).  In MagicLantern, under the Video/Movie tab you need to set recording to start on half-shutter press (on each camera).  One cool feature is that pressing the shutter half-way on one camera has the same effect on the other too!  (I didn't realise this until I had made my own custom cable that includes a button!)

Note that you can end up in the sort-of-amusing situation where whenever you start recording on one camera, that signal toggles the other causing it to stop recording!  (And vice-versa.)  It's easily solved by turning both cameras off and back on again.  It usually happens when I plug or unplug the cable in one camera with them still on, triggering one camera to start without the other.

I'm curious - what software are you using to process and edit your 3D footage?

Leon

[daveesl77]

Using the two camera concept above just made me realize the perfect bypass for the size/time limitation, without a loss of frame or sound. 

1) Is it possible to have Cam1 (master) synch Cam2 (slave) to all coding, frame rates, shutter, etc. ?
2) Make timecodes synched, filenames synched but add in an additional marker to denote the second camera.
3) Make the 2 camera switch to where camera1 is on and cam2 is off.  On the automatic switchover, have camera 1 continue to record for perhaps 2 or 3 additional seconds as Cam2 is coming online. On switchback, same occurs with Cam2 to Cam1
4) With timecodes synched on the videos and similar filenames, aligning in editor would be a breeze.

dave

[Leon]

@dave :  The angle would still change slightly - suddenly jumping to the left or the right.  It would indeed be cool to have the option to have one camera trigger another to start just before it stops recording, and keeping passing it back and forth.  (Even without timecodes they could be synchronised automatically using their audio.)

Overlapping already happens in a messy but usable way, ie with huge overlaps, because even with two cameras started at the sae time on the same bitrate setting and almost identical position one will usually finish at least a few seconds before the other and automatically restart itself recording before the other one finishes.  (The "constant bitrate" is still slightly variable depending on the complexy of the scene.)

Maybe you should suggest this as a feature.  The feature would also allow anything to be triggered externally whenever the video stops for any reason - for example a bell, alarm, flashing light, etc.  Often the camera's beep is hard to hear!

[KarelBata]

Sorry for late reply.

There's a huge mythology surrounding supposed sync fixes that other folks have come up with. None of them work. If they did, everyone would be doing it! You think we haven't tried? 

The use of a remote is completely hit and miss. I do a lot of time-lapse HDR 3D, and use a hard wired controller - with those 2.5mm connectors Leon mentioned. When the cameras are running their click-click-click cycles every few seconds I can hear a time lag between the two. And it keeps changing, with no discernible pattern. I don't see how an infra-red controller would be more accurate than my hard wired one using a Y cord. And to get the level of sync in the picture I posted above would need sub-frame accuracy.

However...

The guys here are very clever.

[antlvk]

It could sync both camera time and in first frame of recording show the time for few second .... like timecode  but need millisecond wonder if that possible.

[luke1100]

Could?......

ML would basically have a option (like virtual recording video) that pauses recording, not saving video frames, waiting for a trigger from the cameras mic/line in.  ML would do this so buffers on both cameras are ready, and external monitors have refreshed. 

If this can be done, you could use a iPhone to send the start recording tone/timecode sound to each camera (one out the left iChannel and another out the right iChannel).  Maybe even have ML stop recording when another tone is sent, and video files on each camera would have the same start and stop, with the exact same numbers of frames. 

Also the iPhone app would keep records of start and stop times, record room audio (for reference only) and let you render a wav/mp3 file of the timecode/trigger for syncing if needed.

[g3gg0]

are we talking about VIDEO or PHOTO?
OP talks about photos...

[vidalipoly]

Using the two camera concept above just made me realize the perfect bypass for the size/time limitation, without a loss of frame or sound. 

1) Is it possible to have Cam1 (master) synch Cam2 (slave) to all coding, frame rates, shutter, etc. ?
2) Make timecodes synched, filenames synched but add in an additional marker to denote the second camera.
3) Make the 2 camera switch to where camera1 is on and cam2 is off.  On the automatic switchover, have camera 1 continue to record for perhaps 2 or 3 additional seconds as Cam2 is coming online. On switchback, same occurs with Cam2 to Cam1
4) With timecodes synched on the videos and similar filenames, aligning in editor would be a breeze.

dave

Hi
it would be cool if two or more cameras such as 5d mk iii could be synced through usb.i mean that one camera would be "master" and the other would be "slave".not only timecode, but all camera settings such as:white balance,iso setting,picture profile,shutter speed,etc
maybe the new EOS 6D with built in wi-fi is closer to this