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Chronos => Chronos User Discussion => Topic started by: dgerrard on August 01, 2017, 12:02:43 PM

Title: Triggering two cameras
Post by: dgerrard on August 01, 2017, 12:02:43 PM
Is there any problem triggering two Chronos cameras using a single trigger going into a BNC splitter that is connected to two cameras?  Something like this with appropriate cables to the cameras
https://www.amazon.com/RiteAV-294114-BNC-T-adapter-splitter/dp/B000V1LX6S (https://www.amazon.com/RiteAV-294114-BNC-T-adapter-splitter/dp/B000V1LX6S)
If the cameras are set up with the same triggering delays, with the two cameras be synchronized?
Title: Re: Triggering two cameras
Post by: tesla500 on August 01, 2017, 04:39:00 PM
Yes, you can do this with as many cameras as you want. If you're triggering more than about 4, I'd recommend turning off the IO pullups on all but one, to avoid having too much pullup current at the switch.

They will be synchronized to within one frame this way.
Title: Re: Triggering two cameras
Post by: AimedResearch on August 03, 2017, 07:49:56 PM
For synchronization it would be best to have an external pulse to control both frame rate and exposure.  You would still want to share a trigger signal.  If you are just triggering both cameras at the same time - sharing a common trigger, you have no control over their clocks.

Think of the frame capture as the series of dashes in the lines below.  Periods just represent time between frames.  T= point in time trigger is received.  If the recording ends at the trigger, it could look like this:
Cam-1 |...|...|...T
Cam-2 ...|...|...|T
The same number of frames (dashes) were captured.  Just not "in-sync".  How close in time the frame captures could be is dependent on frame rate.  At 10,000fps two separate cameras sharing a common trigger would have frame captures within 0.0001 sec (1/10,000) from each other max.  At 1,000fps that time would be longer, 0.0010 sec (1/1000) max.  Obviously the faster your object's motion, the more critical the timing becomes.

When you utilize the Edge Triggered and Shutter Gating features, you are truly synchronizing the cameras, assuming cable lengths are the same to each camera.  Tesla500 would best be able to define the timing resolution in that scenario.
Title: Re: Triggering two cameras
Post by: Camoit on September 08, 2017, 05:56:06 PM
Does anybody know what the max cable length that can be run?
Or the best type to use?

I don't want to be anywhere close to the camera when using it. Great bodily damage to the human behind the lens may occur with what we are shooting with it.
 
Title: Re: Triggering two cameras
Post by: dgerrard on September 08, 2017, 08:12:29 PM
I picked up a wireless system for $12 that has a range of 100m/320ft

http://www.ebay.com/itm/Neewer-860-S1-Camera-Shutter-Release-Wireless-Remote-Transmitter-Receiver-/191616590346?hash=item2c9d3d220a (http://www.ebay.com/itm/Neewer-860-S1-Camera-Shutter-Release-Wireless-Remote-Transmitter-Receiver-/191616590346?hash=item2c9d3d220a)

I have not personally tested it since I have not received my camera but there was a video of someone using it with the Chronos.  I have tested the wireless unit and the resistance drops below 100 ohms which should trigger the camera.

Doug