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StereoSync Project - Synchronizing multiple cameras for stereophotgraphy

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Hi all,


I've been away from the CHDK forum for a long time caught up with many other projects (as well as uni then onto full time job). My triple S110 rig has been working well (thanks to all the help from this forum) and it's had a lot of use since 2014/2015 when I stopped working on it (I have some photos uploaded to https://stereopix.net/josh/ and http://phereo.com/joshn). But now my main project is building an upgraded version of it using 3 Canon G7X cameras.


For anyone who hasn't seen the project yet it is a way to synchronize two or more Canon cameras for stereophotography, synchronizing the shooting settings (aperture, ISO, exposure time, ND filter state etc.) from the master camera to the slave cameras, then synchronizing the shot to less than 1ms difference. This allows the user to control the whole stereo rig using only the buttons on the master camera. It can do continuous shooting with exposure bracketing, and also works with some scripts such as interval shooting.


This time I'd like to make the rig more reproducible by others, unlike the last rig which required soldering in wires onto the camera PCB. I have a few ideas of how to make this work without any hardware modifications to the camera, such as powering them all on at the same time by permanently holding down the power or wifi buttons (and masking when it is on) and applying power to the dummy batteries instead of soldering wires to the on/off switches to put them in parallel. Input can be done through the temp-sense terminal on the dummy battery, output can possibly be through the AF LED read with a photodiode but if there is an electrical output I can tap into that will be better (will make another post for this). Last time I did not actually use any dummy batteries or photodiodes like I planned to, since I was already soldering wires for the power button I just soldered wires to everything I wanted to access including power then brought that out to a separate connector on the outside of the camera.


Last time I also wrote the changes straight into the 2014 CHDK code without making them as patches and never published them anywhere (though I did send to some forum members who requested it). I'm thinking the best thing to do this time would be to write as patches and publish it on a repository somewhere so that anyone else who wants to use it can easily download it and apply it to the latest CHDK code?

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Offline reyalp

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Re: StereoSync Project - Synchronizing multiple cameras for stereophotgraphy
« Reply #1 on: 28 / December / 2020, 16:18:24 »
I've been away from the CHDK forum for a long time caught up with many other projects (as well as uni then onto full time job). My triple S110 rig has been working well (thanks to all the help from this forum) and it's had a lot of use since 2014/2015 when I stopped working on it (I have some photos uploaded to https://stereopix.net/josh/ and http://phereo.com/joshn).
Nice.

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Input can be done through the temp-sense terminal on the dummy battery, output can possibly be through the AF LED read with a photodiode but if there is an electrical output I can tap into that will be better (will make another post for this).
FWIW, as I mentioned in the other thread, on G7X you can control HDMI power for output, and for input you have your choice of HDMI HPD and analog AV detect in addition to battery temp and USB power. HDMI power + HDMI HPD is attractive because the HDMI connector doesn't interfere with using USB for shot triggering, doesn't require an external power source, and unlike the proprietary connector used for analog AV + USB, breakout connectors are readily available.

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Last time I also wrote the changes straight into the 2014 CHDK code without making them as patches and never published them anywhere (though I did send to some forum members who requested it). I'm thinking the best thing to do this time would be to write as patches and publish it on a repository somewhere so that anyone else who wants to use it can easily download it and apply it to the latest CHDK code?
You could certainly do that. You're welcome to use a thread here and make a page on the wiki, and you code can be hosted on github, assembla or whatever you prefer.  If the code changes can be made relatively self contained, they could potentially be included in official source under a camera.h define.
Don't forget what the H stands for.

 

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