Film SLR Flash unit on a Digital SLR - Possible?

Discussion in 'Digital Photography' started by alex, Jun 18, 2006.

  1. alex

    alex Guest

    Had an opportunity today to buy a second-hand flash unit that was TTL
    compatible with Canon EOS Film SLRs. I thought this would simply work on my
    350D and might be a bit of a bargain...

    The guy there said that it wouldn't work because the frequencies (??) were
    all different and that all photos would come out completely white...

    Is this true or not? I thought TTL was a standard (certainly on Canon
    compatible) and that if the Flash supported it and was compatible with the
    connector itself, all would work fine.

    Look forward to your responses, as this would be a good bargain if it did


    alex, Jun 18, 2006
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  2. alex

    Bob Salomon Guest

    Should work fine but the old flash may not allow all of the flash
    functions on your camera. Both your camera and the camera the flash was
    made for have X synch.

    That is what controls the timing of the firing of the flash so the
    shutter is fully open at the time it fires.
    Bob Salomon, Jun 18, 2006
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  3. alex

    alex Guest

    Bob, Thanks for the reply. I'm tempted, it was only £35 anyway so as long
    as there's no dangerous voltages or anything, would be a good starter flash
    and then as I need the extra functions I can upgrade to a 420/30EX with the
    bells & whilstles.


    alex, Jun 18, 2006
  4. alex

    Pat Guest

    Stop Immediately before you use that flash. It is the voltages that
    are different.

    Some, but not all, older flashes used very high shutter trip voltages
    that were WAY above that the digital cameras can handle. Check the
    trigger voltage before you use it and check you camera's manual to see
    what a safe range is.

    It is possible you could damage your camera, i.e. fry the electonics.

    Give you flash model number an someone might be able to look them up
    for you. Or Google it yourself. Another option would be to check the
    website of the manufacturer (or to contact them)

    Good luck.

    Pat, Jun 18, 2006
  5. alex

    Helen Guest

    It's not frequencies that might cause problems. What you have to be careful
    about is the trigger voltage, which is the amount of voltage which passes
    through the camera when you release the shutter. Older flashes could sizzle
    the delicate circuitry of a modern DSLR, which require lower voltages. The
    350D can take a max of 6 volts. Google for "trigger voltage 350d" - that's
    what I did, then find out the trigger voltage for the flash unit you're
    looking at.
    Google is our friend, remember.
    Helen, Jun 18, 2006
  6. alex

    Bob Salomon Guest

    Synch voltage is a different animal. The old flash could have a high
    synch voltage.
    Bob Salomon, Jun 18, 2006
  7. alex

    Bob Salomon Guest

    If the flash is a good buy and you have a built-in flash you could
    always fire the new flash by a slave and that way the synch voltage is
    no problem.
    Bob Salomon, Jun 18, 2006
    /\\BratMan/\\, Jun 18, 2006
  9. alex

    alex Guest


    Yes that sounds more sensible. Given what the some of the others say, I
    will be very weary of the voltages from now on. Thought they just relates
    to studio strobes etc, but didn't know flash units could produce them as

    Thanks alot, and thanks to the others in the chain.


    Alex C
    alex, Jun 19, 2006
  10. alex

    wilt Guest

    Besides the synch voltage issue that is mentioned, a fundamental
    problem with getting ETTL automation out of a TTL flash unit is simply
    that the flash is most likely incapable of the preflash needed for
    metering ETTL prior to the exposure!

    TTL flash was metered in real time from the surface of the film and the
    flash was told 'enough light' based on how much light was reflected off
    the film surface as the exposure was made. ETTL, on the other hand,
    uses a preflash which is metered by a sensor in the camera, but is not
    off the surface of the sensor and occurs BEFORE (not during) the actual
    exposure. No preflash, no ETTL automation!
    wilt, Jun 19, 2006
  11. alex

    Eatmorepies Guest

    The flash I used with my EOS film camera works on my 350D but only at full
    output. However, with the histogram on your 350D you can see if you are
    calculating the correct exposures.

    Eatmorepies, Jun 19, 2006
  12. It will probably work, but only on fully manual - no TTL metering.
    You might also have to hook it up via a PC-connector adapter or put
    insulating tape over the E-TTL pins in the camera's hotshoe to get it
    to fire (depends on the model).

    This also means that you need to work out the correct aperture from
    distance and GN - or use a flash meter.
    His explanation is bogus, but its true that using this flash with a
    digital camera is not as straightforward as a modern flash.
    Unfortunately not. Canon speedlites has at various times used TTL,
    A-TTL and E-TTL (II). These are not compatible. Your EOS 350D uses
    E-TTL II, and will not work with TTl or A-TTL.
    If you are ooking for a bargain, you'll actually better of getting
    a non-dedicated "auto" flash like Sunpak 383 Super. If you buy
    second hand, you need to be careful about trigger voltage.

    Here is a page about buying flash for a Canon digicam:
    In particular:
    Gisle Hannemyr, Jun 20, 2006
  13. alex

    alex Guest

    OK went and had another look and decided to follow all your advice.

    Just ordered the 430EX Speedlite for £169.

    Does everything, very impressed with zero light AF beam - also ETTL allows
    Flash zoom and also detects /1.6 reduced frame on my 350D...

    One more Happy Photographer...

    Alex C
    alex, Jun 24, 2006
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