Vivitar 285 Multi flash setup

Discussion in 'Lighting' started by wilfbiffherb, Jan 17, 2012.

  1. wilfbiffherb

    wilfbiffherb Member

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    Hi,

    I have a Vivitar 285 which i use with the PC connection on my Bronica SQA. I am just wondering if it is possible to get another 285 and sync them in the studio with pc connections or would i have to use the hotshoe and get wireless triggers?
     
  2. CGW

    CGW Member

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    Last edited by a moderator: Jan 17, 2012
  3. Bob-D659

    Bob-D659 Member

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  4. Mike Wilde

    Mike Wilde Member

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    There are schematics on the web of the connection that the optical sensor port on the flash body. One pair of pins is used to trigger the flash when the remote sensor cord is used.

    So it should be possible to create an assembly that includes a peanut slave and a potentiometer that lets you set the strobe on manual and dial back it's output.

    Or you could dial back using the standard sensor, and get a hot shoe slave. Wein makes a reasonable quality collection of them also.
     
  5. Bob-D659

    Bob-D659 Member

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    You can wire three or 4 of them together with pc cords and wye adapters. Just make sure they all have the same voltage on the sync contacts, easily done with a $10 DVM.
     
  6. wilfbiffherb

    wilfbiffherb Member

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    thanks for all the advice. i have just randomly discovered a 3 way pc adater which goes into your camera and allows you to trigger 3 pc flashes at once! and only £11.99!!just need some more flashes now!
     
  7. Ken N

    Ken N Member

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    I'd be a little careful about the multi-pc connector. If any of your flashes is a higher trigger voltage model, it can fry the other flashes--or even the camera in some situations.

    I'd use wireless trigger of some form. Cords are a nightmare.
     
  8. Steve Smith

    Steve Smith Subscriber

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    I use optical slave triggers with mine. Much tidier than wiring them all together.


    Steve.
     
  9. olleorama

    olleorama Member

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    the cheapo ebay radio triggers are aint that bad either.
     
  10. ColdEye

    ColdEye Member

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    Yeah, the Yongnuo stuff is decent, never had misfires with mine (digi and film).
     
  11. Dan Quan

    Dan Quan Subscriber

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    PC cords are indispensable if their use affords you something you can't achieve any other way. Like in an RF controlled environment, or hardwiring to achieve an unusually fast shutter/flash sync speed, such as between 1/1000 sec and 1/8000 sec which can be done on a D70.

    But if you don't need to have the cords laying around, the RF or optical triggers can be safer, more tidy and lead to fewer falling light stands and broken flash heads.
     
    Last edited by a moderator: Jan 17, 2012
  12. MattKing

    MattKing Subscriber

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    I have some old Wein IR triggers that work well.

    Recently though I was surprised when I found that the remote for our digital TV tuner/recorder would trigger the flashes!
     
  13. Steve Smith

    Steve Smith Subscriber

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    A few years ago at work, we were making a circuit for a vending machine which used infra red to detect the position of a cup. I used an old remote control as part of the test equipment.


    Steve.
     
  14. Soeren

    Soeren Member

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    If within economical reach I'd go with radio or optical slave triggers. It probably will save you some strobes in the end and keep you from getting a wounded ego :D you know like in Bussy photog + Cables on floor = :cry:
     
  15. John Koehrer

    John Koehrer Subscriber

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    Recollections are kinda foggy but it seems that by putting two or three flash units through one PC contact that the voltages are added together, not parallel. If you have a multiple adapter it would be easy to check at the point where the single cable attaches.
     
  16. Steve Smith

    Steve Smith Subscriber

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    They won't add together but as the trigger voltage is derived from the HV capacitor via a high resistance, the voltage of the combined connection will be around that of the highest voltage flash.

    However, some flashes (my 285s included) measure 5.6 volts which I think shows that there is a 5.6 volt zener diode limiting the voltage. In that case, it might pull the voltages of all the other flashes down to this level too.


    Steve.
     
  17. John Koehrer

    John Koehrer Subscriber

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    The PC cord doesn't see trigger voltage, only open switch from the 6V batteries.
     
  18. Steve Smith

    Steve Smith Subscriber

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    Within the flash there is a high value resistance (about 1M ohms) connected from the high voltage supply to a small capacitor (about 10nF) which is then connected to the primary of the trigger transformer (the other side being connected to ground).

    As the main high voltage capacitor charges, so does the small trigger capacitor. The sync. cable is connected between ground and the junction of the resistor and capacitor so that when the shutter contacts close, the capacitor is connected across the trigger transformer primary. The energy in this small capacitor discharges into the trigger transformer which causes a high voltage pulse to appear on the transformer's output. This pulse ionises the gas in the flash tube and causes it to start conducting, taking the charge from the main high voltage capacitor. It will continue to conduct until the charge is gone, or in the case of thyristor flashes, until the thyrystor circuit stops it conducting.

    So the voltage present on the sync. connection is likely to be the same as the internal high voltage supply unless it is limited by a zener diode or resistor network.


    Steve.