Sunpak Auto series flashes

Discussion in 'Lighting Equipment' started by hjoseph7, Mar 2, 2021.

  1. Back in the film days I never really thought about flash units since I rarely used them. When i decided that I needed a flash unit mostly for event or wedding photography, I stuck with dedicated flash units made by the manufacturer(Canon/Nikon) or I went with a Metz . However, I did hear about 3d party flash manufacturers such as Sunpak that had a huge loyal following. I wondered why, but never bothered to follow up on my curiosity.

    A few days ago I decided that i needed a small manual flash for my Pentax Spotmatic F (circa 1960's) since i decided to get back into film. I didn't really need anything fancy just a flash unit that would flash a burst of light in dim lighting situations. OK since Thyristor technology was the rage before TTL, iTTl eTTL etc I figured you might as well throw that in . I didn't want to get stuck trying to read those complicated charts on the back of the flash unit in dim lighting with my old eyes.

    Anyway my curiosity for Sunpak flash units finally kicked in, so I went on eBay to see what they had available. Sunpak made a series of Thyristor units which were numbered 211, 322, 411, 555, 611, I think the later 2 were hammer-heads and were hugely popular.

    These flash units are currently selling for peanuts on eBay, so If they came DOA or had other issues, it would not be a big deal. First I purchased the 411 (because it looked nice in the picture) for $20. Unfortunately, it was way to big and not pocketable like I wanted. It might work on my Mamiya medium format though ?

    The thing I noticed about this Sunpak is that it was really well made, not cheap plastic. It came with a well written (English only) manual with large lettering so you don't need the magnifying-glass down while reading it. The flash came in almost mint like condition, but I have yet to test how accurate it is. It allows for bouncing off the ceiling, or wall. Comes with an illuminated control panel in the back, plus it allows a power pack.

    Anyway, since this flash was too big, I went back on eBay and got the 211($14.99) which is the smallest unit in the series. While I was at it I also got the 322 since it was selling for $17.95(free shipping).

    The Auto322s arrived first. It still is a little bit to big for my pockets, but what a wonderful little flash ! It reminds me of my Nikon SB-15. This flash can tilt and bounce anyway you want it to. But the best thing about the Auto322s, is how easy it is to read the control panel in the back. In manual mode there are 4 slide controls(Power, Feet, Fstop, ASA). You just move these slides up and down until you get the right combination since they are all linked together. There is no guessing, squinting or complicated color codes.

    The 211 has not arrived yet. I'm guessing its the simpler of the two, but size is my main priority so no big deal. Does anybody know how much these units actually cost, back in day ?
    Last edited: Mar 2, 2021
  2. Thyristor technology was, and still is, used by nearly all flash manufacturers. It's just that Sunpak made a big deal of it by plastering the word 'Thyristor' across any spare space they could find on their flashguns.

    A thyristor is used to cut off the supply of energy to the flash tube, and thereby regulate the exposure. Before that, little gas-discharge tubes were used. The difference being that the discharge tube 'dumped' and wasted the excess capacitor charge. Whereas use of a thyristor preserves the unused charge and increases the efficiency of the flash several fold. It also makes the recycle time shorter when a full discharge isn't needed.

    Sunpak are an OK make, but personally I prefer Nikon's film-era speedlights. Their Auto-Aperture mode gives extremely accurate exposures, and can be used with any camera that has a standard hotshoe. The Nikon flashes have also had a very low - 5 volt - trigger voltage ever since the SB-24. Maybe earlier. I don't think I've paid more than £25 UK for any of my used film-era Nikon speedlights either.

    I recently measured the open-circuit P.C. connector trigger voltage on a Sunpak AutoZoom 3600. It was 350 volts! Beware.

    I think I paid nearly £70 for an AZ3600 in the 1980s.
    Last edited: Mar 3, 2021
  3. I just dug out a couple of little Sunpaks I had lying around. I don't even remember buying them, so they must have been cheap.

    The larger one - still not very big - is an Auto Zoom 2400. I measured the Guide Number as 18 (metres/100 ISO) using a flashmeter, and verified it with test shots on a digital camera. The open-circuit trigger voltage is 300, both on the P-C plug and on the hotshoe. So don't go using one on a digital camera, unless isolated with a radio trigger.

    The smaller model is an Auto 122. This has a measured and verified GN of only 16. The O/C trigger voltage is a whopping 325 volts though.

    A peculiarity of both these flashes is that the P-C plug has to be 'parked' in the body-socket before the hotshoe can be used.
    Last edited: Mar 3, 2021
  4. The Sunpak flashguns have a very mixed bag of trigger voltages, many are disturbingly high:

    LINK ----- Photo Strobe Trigger Voltages

    Whenever I get a flashgun the first thing I do is check the trigger voltage. If it's more than a few volts, the bin awaits.
  5. I wouldn't use them on any Digital cameras ...
  6. That Botzilla site is a bit of a menace.
    Reason? The contributions are made by random people who obviously have no clue about accurately measuring high-impedance voltages - which most old flash trigger circuits are.

    The trigger circuit commonly used in many old flashes uses a small capacitor charged through a high resistance, of anywhere from 1 to 10 or more megohms. So just sticking a 10 Mohm digital voltmeter on the trigger pins will give a false, and low reading.

    Long and short of it is - if that Botzilla site lists the trigger as anything over 150 volts, you can be sure that the voltage will actually be more like 300 to 350 volts!

    The proper way to measure those high resistance circuits is with an electrometer (expensive). Or by taking two readings with a voltmeter of known input resistance. One reading straight, and another with a resistor equal to the voltmeter's in series. A bit of maths then allows you to work out the true open-circuit voltage, as well as the unknown source resistance of the trigger. It nearly always gives a voltage of over 300 volts with those older flashes.
  7. I agree that it can be misleading, and it's certainly out of date. However it does at least explain the trigger voltage problem, which many photographers aren't aware of, including, apparently, the OP. If you follow the link in Botzilla about measuring the voltage, it says that the meter must have an internal resistance of at least 10 megohms. I know this will still depress the open circuit voltage,but in the real world, few people have a valve voltmeter or similar (I'm afraid my education in electrical engineering is half a century old).

    In general, non third party flashguns made for electronic film cameras and digital cameras tend to be safe. One notable exception is the Olympus Quick Auto 310 which was the first TTL flashgun for the OM2, it has a trigger voltage approaching 300V although it's not listed in Botzilla. It's successor the T32 is safe.
  8. That's still nowhere near high enough to measure the open-circuit voltage accurately. You'll likely get a reading of maybe 180 volts, where the true voltage is closer to 350.

    Now Nikon clearly state that their pro and semi-pro cameras can withstand up to 250 volts, but that's not 350 volts. So if some unwary Nikon owner sticks a 10 Mohm meter across their flash and only gets a reading of 180 volts, they might think it's safe when it most certainly isn't.
    See the issue?

    I've emailed the guy that runs the Botzilla site in the past and tried to explain the problem. With no response.
    Last edited: Mar 5, 2021
  9. P.S.
    The solution is: If in doubt - use a cheap radio trigger.
    These usually use 400v capable trigger components. And if it gets zapped.... well at least you've only lost a cheap trigger and not an expensive camera.
  10. Judging by the cameras mentioned in the site, and the lack of reference to recent flashguns, I suspect it hasn't been updated for around 15 years.
    rodeo_joe|1 likes this.
  11. My Auto211 came in the mail. it works OK but once in a while it freezes and you have to take the batteries out and put them back in .
  12. Sounds as if the battery contacts are dirty or intermittent.

    The circuitry in that old flash has no CPU to 'freeze'. It's just basically a simple inverter circuit that steps the battery voltage up to 300 volts or more. On, or off (powered or unpowered) are its only two 'logic states'.
  13. After I turn the flash off, the ready light still stays on which means I have to press it to get rid of any voltage remaining in the capacitor(s) ? This works most of the time but sometimes, the ready light stays on and I cant't turn it off no matter how hard I try ? This is when I remove the batteries and put them back in and everything is back to normal ?
  14. Not necessary.
    It's worse for a flash capacitor to stay in the discharged state for a long time, because the dielectric is a chemical film formed by the electrical potential between the 'plates'.

    With no potential there, the dielectric tends to break down and dissipate into the chemical paste from which it came. This means that next time it's used extra energy has to be put into the capacitor to re-form its dielectric. Which is why long-unused flashes often take a considerable time to charge up when they're first turned on.

    Also the dielectric may not re-form completely, reducing the capacitance and hence the 'power' of the flash.

    In short; putting the flash away charged may be beneficial, and will certainly do no harm.

    WRT the ready light: This is usually just a neon and limiting resistor across the capacitor. Once the neon bulb has struck, the voltage to maintain the plasma can fall back considerably before it goes out. So it's quite possible for the 'ready' light neon to be alight while there isn't sufficient voltage to fire the Xenon flash tube itself.

    Plus. These things are old! They can't be expected to perform perfectly. Like the human body!:(
  15. OK thanks Joe !

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