DIY camera trigger from another camera

Discussion in 'The Projects Forum' started by huerta123, Apr 10, 2013.

  1. huerta123

    Thread Starter New Member

    Apr 10, 2013
    3
    0
    Hello,

    I am a photographer and like to do a lot of DIY stuff. I am researching how I could build my own camera trigger and avoid using wireless triggers which cost $$$$. What I want to do can be done with wireless triggers, but I want to build my own circuit.

    I have a camera that has a pc-sync port. Everytime a photo is taken, there is a current going through this port, through a cable (this cable has only 2 poles, ground and positive). This current is received by a flash unit and it triggers the flash at the same time the camera takes the photo. This is how it works normally.

    What I want to do is to be able to trigger a second camera everytime I take a photo with the first camera, instead of triggering a flash. There are a few things to take into consideration:


    1. The way the second camera is triggered is by generating a short circuit. There is usually a cable connected to a jack, and by pressing a button a short circuit is generated and the camera triggers itself.
    2. I do not know what the voltage or current is coming out of the first camera (the one doing the triggering) through the pc-sync port. I still need to do this.
    3. I do not know if I should use a transistor or a relay for a switch.
    4. Because the first camera and the second camera need to be fired at the same time (so that the photo is the same on both cameras) there cannot be any lag when activating the triggering switch.
    How can I do this? The idea is to have a circuit that will detect the voltage or current change coming from the first camera and close a switch and cause a short circuit so that the second camera is triggered.


    Thanks!
     
  2. Markd77

    Senior Member

    Sep 7, 2009
    2,803
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    If both cameras have remote triggering it is probably better to have a box that just fires both cameras at the same time.
    There otherwise will be a difference in timing because the first camera waits for the shutter to be fully open before triggering the flash (maybe 1/100 second). Then there is the shutter lag of the second camera (unknown at the moment).
    Triggering both together, hopefully the two shutter lags will be about the same.
    Depending on the camera, it may not even activate the flash for higher shutter speeds than about 1/100 seconds, because the shutter is never fully open, it's just a moving slit.
     
  3. huerta123

    Thread Starter New Member

    Apr 10, 2013
    3
    0
    @Markd77 Yes, both cameras have ports for remote triggering, so indeed I think your proposed approach of having a box that triggers both cameras is a good one.

    Both cameras are triggered by generating a short circuit. So assuming that I want to just press a button and have them both triggered, how could I go about doing this?

    I should mention that the target shutter speed is 1/500. I use leaf shutters.
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,393
    In order not to electrically connect both cameras together (which could cause damage), you would need a separate circuit for each camera. This could potentially be done with a normally open DPST momentary pushbutton switch. Even then, there is the possibility that one set of switch contacts might close before the other, and so the cameras might not operate at exactly the same instant. It would depend upon the mechanics of the switch.
     
  5. Markd77

    Senior Member

    Sep 7, 2009
    2,803
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    It could be as simple as a DPST, normally open, momentary, push button switch. I imagine both circuits in the switch will be very close in timing to each other, but couldn't find anything in the datasheet I found.
    If you want to go more complicated, I've used a NPN transistor to trigger my DSLR, you need to find out which pin is positive on the trigger port for that.
     
  6. huerta123

    Thread Starter New Member

    Apr 10, 2013
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    @tracecom Yes, I would like to keep the wiring seperate so as to not cause damage to the cameras. You mention that the mechanics of the switch might not allow the cameras to trigger at the same time. If that was the case, then isn't there a way to insert a delay on one signal (preferrably an adjustable delay) maybe using a capacitor?

    @Markd77 I don't mind going more complicated :) Btw, what would be the advantage of a transistor over a DPST switch? Speed?
     
  7. Markd77

    Senior Member

    Sep 7, 2009
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    The advantage of transistors (it's probably better to use optoisolators or SCRs - they do basically the same job but provide isolation) is that a single switch can trigger both at exactly the same time, eliminating any possible timing difference in a DPST switch.
    I think the difference in shutter lags probably will make more difference.
    I'd suggest as a first try, two of this circuit, connected to a pushbutton and battery where it says "to Arduino output pin":
    http://blog.newfocusphoto.com/projects/arduino-based-camera-control/
    If the timing is not good enough between the cameras then you can add a circuit like this to the "fast" camera:
    http://www.hiviz.com/tools/triggers/triggers4.htm
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,447
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    You may be able to find some situations where you want the second camera to trigger not exactly at the same time as the first camera but with a slight delay. Hence it might be useful to have an adjustable delay between triggers.
     
  9. BReeves

    Member

    Nov 24, 2012
    412
    64
    One switch + two diodes = done deal.

    Measure the trigger wires to see which is positive, connect the anode of the diodes to the positive wires, connect the other end of the diodes to the switch. Connect both negative trigger wires to the other side of the switch.
     
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