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Firing two dozen flashbulbs...at once.


richard_boulware

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This might be a question for seasoned citizen photographers. Back in

the '80's, I had occasion to need to shoot off a dozen flashbulbs at

once, to photograph a night parade, at a big celebration. After

testing, I learned that using a 12V auto battery would not fire a

city block long line of bulbs that were hard-wired. I found a guy in

Texas who made a unit that used a 90V radio battery (dry cell) and

incorporated a triggering circut so that the 90V didn't fry your

shutter contacts. Have a job where I need to do the same thing today.

Anybody ever heard about this technique, or who that guy might have

been. Richard Boulware - Denver.

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Richard,

 

I don't know the name of your guy, but commercial photographer O. Winston Link photographed the last American railroad line using steam engins from about the mid 50's to 1960. He worked at night using a view camera and scores of flashbulbs. One album of those night images, "Steam, Steel & Stars" (1987), has appeared, and more of his work can be found in "The Last Steam Railroad in America." I am not sure if he revealed his technique for firing large banks of flash bulbs.

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Today we would do it with a two dozen strobes each fitted with a Pocket Wizzard receiver or maybe one per group. <p>

Flashbulbs are no big deal if you still want to go that route. As you found out you need to use more than a low voltage since you are using small gauge wire and a number of flashbulbs. <p>

You could connect a number of batteries in series to give you the required voltage. If 90 volts worked for you the last time it should work for you again. A simple relay (the faster the better) that can handle the current (measure the current at about 90 volts needed to fire one flashbulb and multiply by 24, also keep this total current in mind when selecting batteries) can be used to trigger the circuit from a lower voltage battery source through the shutter contacts.

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I've never had a job where I needed them yet but we've got a locker full of the f33 bulbs that burn for a full 1.3 seconds. They're the big household screw base. You can still buy the 2 screw porcelains just about anywhere for those. You'd likely want the big #25's. They've gotten awfully pricey lately. 5-8 bucks apiece or more. And then you want a relay box. An old lighting contactor with 4 sets of points would allow you to put 3 lamps per channel. Sounds fun to do just because nobody does it anymore. If you look at O. Winston Links stuff closely though you will see more blur than I'd be happy with. A couple of dozen 283's might make good sense.
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The old "American Photographer" magazine, may it rest in peace, had an extensive article on Links photography. It went into some detail on how he set up his flash system. If you can find a back issue somewhere that would be helpful. I'll look thru my old stack.

 

The new "American Photo" is basically a piece of dodo as far as I'm concerned. But hey that's why they make chocolate and vanilla.

 

Eric

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Don't forget you'll have to use an older shutter with M-X sync on M. I'm going to look into it some more tomorrow but it seems to me we wired our mass multiple shots with 110v house current. AC travels so much better. Plus you could rent about a billion feet of #12 cords and hook everything up that way. Nice and safe and no questions from the public.
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This isn't a hard job, but 90V DC distributed down a city block is

hazardous enough that you should get a qualified electrician to

work on it. Knocking together components from internet

recommendations is a good way to hurt someone.

 

Is there any reason you can't have multiple low-voltage circuits?

Slaves are cheap enough these days, and the big bulbs burn so

long that synchronising them won't be that tricky. Just group the

bulbs together in strings that a car or motorcycle battery can

handle, and give each group a peanut slave or tap off a long

regular sync cable line.

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This may be going off at a bit of a tangent, but back in the early 60's we used about 900 bulbs on 1 shot. I was the assistant and I had to physically tape them together in blocks. Only 1 was wired and the others were set off by the heat of the touching bulb. This method won't be of any use if the bulbs need to be spread over a long distance of course.<p>BTW, if you do use this method then obviously you need a time exposure and very dark glasses!
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You only need a high voltage if all the bulbs are wired in series, and that's a foolish thing to do, because one bad bulb will prevent the whole lot going off.<p>If you wire the bulbs in parallel, then you only need about 6v to set them off, but with a lot of current available. If the distance between bulbs is considerable, then there'll be a voltage drop down the cabling, and you'll have to use a slightly higher voltage to compensate, but 12 to 24 volts ought to be enough.<br>An electronic relay should be able to handle enough current and not blow your shutter contacts.<p>There may a problem with directly wiring flashbulbs in parallel, in that the burning metal wire inside the bulb may momentarily short the whole circuit, so that the bulbs don't go off simultaneously. You could prevent that by having a small resistor (say 10 ohms) wired in series with each bulb, and then parallel wiring all the resistor/bulb combinations together.
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My guess is, that your problem the first time around was voltage drop in the block-long wiring lashup; remember that a car battery can deliver several hundred amps. If you're committed to flashbulbs for some reason (over electronic flash) then consider (a) using large enough wire to minimize the voltage drop over the distance, (b) adding a second or third battery so the voltage at the terminal end is high enough, or © putting two or three batteries at locations down the line, firing fewer bulbs each, and use relays to fire all the bulbs simultaneously. An easier way, IMO, would be to use a bunch of electronic flashes with slaves; just use a long enough shutter speed to catch them all.
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