Multi-camera trigger

Discussion in 'The Projects Forum' started by RC Fisher, Sep 29, 2008.

  1. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    I have a little project to control the shutters of 2 or more still cameras. I am interested in using optoisolators to keep all of the cameras isolated from each other while triggering them from one switch. How would I do that and what optoisolator is suitable. Oh yea I am a newby, I am good with mechanical but not so hot with electronic design. And yes I can solder.

    Thanks
    RC Fisher
     
    Last edited: Sep 29, 2008
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Perhaps you could give us some information. What does it take to trigger a camera? Can it be done electronically, or must it the through a mechanical switch?
     
  3. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    All of my cameras use just a contact closure to trigger them. I have been told by Canon, the cameras I am using on this project, that if all the cameras are tied together on the same switch it will blow up all of the cameras electronics. So each camera needs to be isolated. I have done this before with reed relays but they get pretty expensive for multiple cameras. I need 2 circuits for each camera one with the half press, activate focus & so forth, and full press for the exposure. I kow I will need to make a 5V power supply to feed current to the LED side of the optocoupler when the switch is closed but is there anything in the other side of the circuit? I was going to use a pretty common/simple optocoupler. The remote circuit from the camera is just 3 wires, common, half press and full press. I figured the common can go to both opto couplers and then the out of each one can go to half press then full press. I had planed on using the DIP 16, 4 coupler version of the optocoulper so I can do 2 cameras with each IC package. It should be easy to scale up for lots of cameras. I am not looking for millisecond control of the cameras just control.

    Is this enough info?

    Thanks
    RC Fisher
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    Do the cameras have a connector installed for the function? Do you have information about this connector and the internal connections?
     
  5. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    Yes there is a connector, it's a basic 1/8 stero plug with 3 contacts. Common, half press and full press. Remote switches sold are just contact closure switches. I don't have any other info that that. I guess I could call Canon for other info.

    Cheers
    RC Fisher
     
  6. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    OK just talked to Canon, they were abosolutely no help and I don't have one of the cameras in my hands at the moment. lets assume, I know this is silly but maybe it will provide information I can use once I get the camera, that 5v of some sort comes out of the each of the 2 trigger lines so that when you push the button it fires the camera. What can make that circuit complete?

    Is that enough for a educated guess?

    Cheer
    RC Fisher
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    The connector and the pinout are available online. But it's not safe to mess with internal electronics with an optocoupler. A contact closure is definitely best, and relays are available for $1.00/ea.

    The question now gets to how many cameras you want to be able to control, and at what distance? Do you want all the switches and relays in one central location? You can have a master focus control and a master shutter control, and be able to use more switches to select which camera/s to operate.

    Can you make a PC board, or do you want something that can be done in an enclosure with the components glued down and point-to-point wired? You have your choice of 5, 6, 9, 12 and 24 volts DC for the relays. Can you solder and follow a schematic?
     
  8. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    Well where are you getting them for $1. I found them at Mouser and for a DPST reed relay are about $8 USD. A 4 channel optocoupler is $1.50 as opposed to a miniature reed relay at around $8. That was my plan A but figured if I could do the entire thing without relays I might be better off. Plus there might be issues on how quickly the relays pick up.

    Cheers
    RC Fisher
     
  9. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    Basicly the control is for the 4 cameras in one spot, fired together.

    I can do the mechanical work, boards, soldering, packaging, etc. It's some of the design work I can't wrap my head around. I built a motion control setup several years ago and used reed relays in a small package and they seemed to work well I was just looking for a better way!

    I am hoping to have the cameras in about a week but I have to order the parts soon so they show up together.

    Thanks for your quick responses.

    Cheers
    RC Fisher
     
  10. beenthere

    Retired Moderator

    Apr 20, 2004
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    Check on page 1647 for the Omron G5lE-1A4-xx series. They are SPST (all you need) and $.96/ea. Ok, so you will need two per camera.

    I advise against optocouplers unless you know exactly what you are dealing with inside the camera.

    What are the timing requirements?
     
  11. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    All fire at the same time, for now. I was just going to gang them onto the same switch.

    cheers
    RC Fisher
     
  12. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    Well I think smaller packages would be better, those relays are pretty big. I am looking at the Magnecraft 528-171-21 DPST relays ($3.73). The relay coils need 50ma so I think a 9V battery through a regulator would last a while. Very small DIP package to make the smallest form to fit in my setup. The wiring and conectors will take more space but oh well.

    Do you think that something like the Avago solid state relays, Mouser # 630-ASSR-1228-002E might work? Pg 1683.

    Cheers
    RC Fisher
     
  13. beenthere

    Retired Moderator

    Apr 20, 2004
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    SSR's latch if the signal through them is DC. That is why I am pushing mechanical relays.

    The bad news is that your 9 volt battery won't be able to pull relays for any length of time, nor will it last. Think of multiple AA's for reliability. The output of 4 is close enough to 5 volts to need no regulator.
     
  14. RC Fisher

    Thread Starter Member

    Sep 29, 2008
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    The relays would only draw power when you press the trigger, maybe 1 second for each actuation. Total draw of 200ma. Maybe I'll use 2-123 lithium batteries, but I have to find a holder. I could also use 2-AAs and a "MintyBoost" step up thinggy, that will fit the case I want to use. I just buy the kit from Adafruit <http://www.adafruit.com/index.php?main_page=product_info&cPath=10&products_id=14>

    The lithiums are pricey but they really last a long time.

    Cheers
    RC Fisher
     
  15. SIcam

    Active Member

    Aug 9, 2008
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    I have been driving a Sony P-41 camera for ON/OFF and for Shutter trigger with a 2532 Optoisolator for the exact reason you want to. The camera internally uses direct contact for trigger and I wanted to isolate the control board voltage from the camera voltage. I current limit the optoisolator with 1K ohm from the output on the control board and I current limit the camera with 1k ohm. I have been able to put 10k ohm on/off from camera to opto and 5k ohm for shutter trigger of the camera.

    Here is an example that I followed:
    http://www.glacialwanderer.com/hobbyrobotics/?p=10

    Mechanical relays are noisy and can have a lag to them.

    Understand your cameras and you can set them up with Optoisolators or even with MOSFET's. Opto's are simple to connect though.

    You could also look into the following method:
    http://www.glacialwanderer.com/hobbyrobotics/?p=13

    http://wordpress.bolanski.com/?p=9
     
    Last edited: Sep 29, 2008
  16. RC Fisher

    Thread Starter Member

    Sep 29, 2008
    10
    0
    Thanks.

    I am going to try the optocoupler and see if that will work for me with the relays as plan B. I had one friend check the cameras and he said there is 3-5v coming out of the focus and shoot lines going to the common so that should be easy direct hook up with just one resistor on the LED side. Hopping to test next week.

    Thanks again.

    Cheers
    RC Fisher
     
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