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Thread: old flash on Canon 400D

  1. #1

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    old flash on Canon 400D

    I've just discovered that I may be damaging my Canon 400D by sticking an old flash gun onto the hot shoe so I've been Googling to see what I can learn.

    Background facts:
    1) My 400D was purchased in May 2007.
    2) The old flash gun is a Unomat 320 TCD NB not the twin version, it dates from 198?

    Discovered so far:
    1) Voltmeter readings across the flash PC cord as the flash fires ranges from around 16V to 19V.
    2) This page http://www.botzilla.com/photo/strobeVolts.html says the Unomat 320 TCD has a trigger voltage of 34V, since mine is showing about half that I reckon the 34V reading cited is for the 'twin' version of the 320 TCD.
    3) The same page says the 320 TCD is NOT 'EOS safe', since that page also says Canon's have a 6V limit.

    4) This page http://digitaljournalist.org/issue0703/tech-tips.html was authored by someone who at the time of writing (2007) had worked for Canon since 1982. The page clearly states that a 400D is "safe for TCV up to 250 volts".

    Does anyone here have any wisdom on this issue?

    Ken

  2. #2
    rpcrowe's Avatar
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    Re: old flash on Canon 400D

    From Tech Tips by Chuck Westfall (Canon’s director of media and consumer relations)
    Canon Digital SLRs safe for TCV up to 250 volts: includes
    EOS Digital Rebel XTi, XT (400D/350D)

    If you are measuring the sync voltage of your flash unit correctly, it should be safe to use it.

    It was really a PITA when Canon SLR/DSLR cameras were only safe up to 6V. I personally think that this was a ploy to force folks to use Canon flash units on their DSLR cameras. (REALLY! Could Canon, who designed their EOS cameras so that Canon MF lenses could not be used, posibly be guilty of such a neferious plot?)

    Canon Digital SLRs safe for TCV up to 6 volts:
    EOS 10D, D60, D30
    EOS Digital Rebel (300D)

  3. #3

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    Re: old flash on Canon 400D

    Quote Originally Posted by rpcrowe View Post
    From Tech Tips by Chuck Westfall (Canonís director of media and consumer relations)
    Canon Digital SLRs safe for TCV up to 250 volts: includes
    EOS Digital Rebel XTi, XT (400D/350D)

    If you are measuring the sync voltage of your flash unit correctly, it should be safe to use it.
    When you quote Chuck Westfall you are restating what I found Chuck had said at http://digitaljournalist.org/issue0703/tech-tips.html so that's encouraging.

    As for measuring the voltage don't know if I did it correctly or not. What I did was:
    1) Attached the PC cord.to the flash unit.
    2) Let the gun charge fully.
    3) Set a mobile phone to video the display of my voltmeter.
    4) Connected the meter's negative to the outer ring of the PC cord and the positive to the inner pin.
    5) When the flash fired the phone video recording was stopped.
    6) The video was played back several times and paused at when the peak voltage was displayed.
    7) This was repeated three times.
    8) The peak voltage readings across the pins ranged from around 16V to 19V.

    Is that OK? Or have I missed something?

    Ken

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