hoola

In another post subject of trigger voltage came up . How does one measure trigger voltage ? How much is too much ? How much is too little ??

rcarol

You can measure the trigger voltage by placing the leads of a voltmeter across the trigger contacts of the strobe. That will tell you how much the trigger voltage is. Then you will need to do some research to determine what the maximum voltage your camera can tolerate. You may have to contact the manufacturer to get this information as it may not be readily available on the internet.

newtoyou Loc: Eastport

Be safe. Take no chances. Use an inexpensive ($15 or so to your door) wireless remote. Can't find it? Text me private at UHH.
Bill

RWR Loc: La Mesa, CA

Some information here: http://www.botzilla.com/photo/strobeVolts.html

TriX Loc: Raleigh, NC

It depends on the trigger circuit whether just measuring with a DVM will be accurate. All the strobes I’m familiar with use a trigger coil, and when the flash is fired and the magnetic field in the coil collapses, a reverse polarity pulse will be generated. How much of that pulse finds its way back to the contacts depends on the circuitry between the coil and the contacts. In my opinion, the only accurate way to measure the pulse is with a storage oscilloscope. Lacking that, I’d always use an isolator between the camera and the strobe (as mentioned above) - it’s cheap insurance.

For those so inclined, here’s a typical circuit. In this case, there is an SCR firing the trigger coil and the question becomes how much of that reverse polarity pulse find’s its way back through the gate, through the op amp to the contacts.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

Set thevmultimeter for DC voltage in the 200 volt range. Apply the red (+) test lead to the center synch contact on the foot of a speedlight. The black (-) test lead goes to the base of the foot. In older strobes or studio flash gear, you probe the H type socket or the camera end of a synch cord attached to a 1/4 inch or smaller "phone" plug.

If the reading reveals a value exceeding the cameras specified limit, use a Safe-Synch adapter.

hoola

Thanks to all for your replies . Is there such a thing as too low of a trigger voltage from flash ??? To the point where flash doesn't fire ? I have an old Bowens Illumitron flash slide duper . Have no idea what its trigger voltage output is . So to play it safe I used Wein hot shoe to pc adapter which lowers trigger voltage . However then duper would not fire . Removed adapter and it fired fine . Nikon D5300 .

PHRubin Loc: Nashville TN USA

Modern cameras and strobes use digital logic circuitry which works off ~5 VDC and can tolerate only a little higher than that. Older flashes use higher voltages. They can be as high as a few hundred volts. I got one heck of a shock from one of those. Needless to say, that flash would fry a modern camera.

rcarol

I don’t think you are entirely correct. My Canon cameras can tolerate 250 VDC and I’ve read that the same is true of Nikon.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

PLEASE READ THIS BEFORE YOU MESS UP YOUR CAMERA:

Re: Canon:

Old flash units - both studio and hotshoe-mount - used pretty high voltages between the camera and the flash - often from 25 to 250 volts. This is because the flash units were fired by simple switches - electrical contacts.

Modern cameras, however, rely on electronic circuitry rather than electric switches. This allows for more flexibility and the possibility for computerization, but the circuits can't withstand high trigger circuit voltages (anything above 6 volts, in the case of EOS cameras, according to Canon) and can be damaged by units with high trigger voltages.

Note that this 6 volt limit does not necessarily apply to PC sockets. Canon states that its 1D digital camera, for example, is capable of withstanding trigger voltages of up to 250 volts when firing flash units with its PC socket. The 6 volt limit applies to the camera hotshoe only. Unfortunately Canon doesn't always state what trigger voltage the PC sockets on all of its PC-socket-equipped cameras can withstand, so if this information is not supplied in the manual you should probably contact Canon.

Anyway. If you intend to connect an old flash to your EOS camera's hotshoe be absolutely sure that its trigger voltage does not exceed 6 volts. You can measure this with a voltmeter. Various accessories, such as the Wein Safe-Sync hotshoe unit, can be used to protect the camera from these high voltages if you want to use such a flash. Even safer are optical triggers since there are no physical connections between the camera and flash unit at all.

Note that the damage to the camera can apparently be subtle and cumulative -simply hooking up the flash and seeing if it works is no guarantee that the high voltage isn't slowly damaging your camera's flash circuit. (of course, Canon is probably being a bit conservative with its 6 volt limit, so you probably aren't taking a huge risk if the voltage of your flash unit is a tiny bit over) Note also that the power supply used by the flash is irrelevant - it has no bearing on the trigger voltage. Many Canon Speedlite flash units, for example, can use high voltage battery packs but they still have low trigger voltages. And portable battery-powered flash units may require 6 volts in battery power but nonetheless may step up the trigger voltage considerably.

An additional problem is that some older flash units have reversed polarity. EOS cameras all have a negative ground and a positive centre pin on the hotshoe itself, though some pro models have polarity-detecting PC connectors that can work with either type of flash unit.

Finally, some flash units have all-metal hotshoes. This can be a problem if they inadvertently short out any of the four small data contacts on EOS cameras. If you have such a camera you could cover up the contacts with electrical tape or use a PC cord adapter so the flash unit doesn't plug directly into the camera's hotshoe mount at all. The same applies if your flash unit has a really large central contact. EOS cameras have fairly small hotshoe central contacts with four tiny data contacts below it. If your flash unit's hotshoe contact is so large that it shorts out any of the data contacts you may damage your camera.

More info:
Canon D30 – 6 Volts (hotshoe or PC connector)
Canon D60 - 6 Volts (hotshoe or PC connector)
Canon 10D - 6 Volts (hotshoe or PC connector)
Canon 300D Rebel - 6 Volts (hotshoe)
Canon 20D – 250 Volts (hotshoe or PC connector)
Canon 30D – 250 Volts (hotshoe or PC connector)
Canon 350D XT - 250 Volts (hotshoe)
Canon 400D Xti - 250 Volts (hotshoe)
Canon 40D - 250 Volts (hotshoe)
Canon 5D - 250 Volts (hotshoe or PC connector)
Canon 1D - ? ? ?
Canon 1Ds - 250 Volts (hotshoe or PC connector)
Canon 1D Mark II - 250 Volts (hotshoe or PC connector)
Canon 1D Mark IIn - 250 Volts (hotshoe or PC connector)
Canon 1D Mark III - 250 Volts (hotshoe or PC connector)
Canon 1Ds Mark II - 250 Volts (hotshoe or PC connector)

Nikon D40, D40X, D50, D70, D70s, D80 & D100 – 250 Volts (hotshoe)
Nikon D1, D1X, D1H, D2X, D2Xs, D2H, D2Hs, D200 – 250 Volts ((hotshoe or PC connector)

ALWAYS chek you camera's users manual to verify the recommended limits. Always check the voltage on the flash unit. Even if the correct trigger voltage is listed or specified, a malfunction in the flash can cause elevated trigger voltages.

There is such issue with too low or insufficient trigger voltage unless the flash units is malfunctioning, however, if a Safe-Synch or similad device is used unnecesserally, where the trigger voltag is already low, the flash my not synchronize or fire when the shutter is released.

The camera's synchronization mechanism within the shutter mechanism simply act as a switch that acrivates the flash when the shutter is fully open. Exvessive curret across the switch will harm it or cause "spikes" or other electrical irregularities that will affect other related circuitry in the camera. The level of trigger voltag is separate form the operatig voltage, stored in the capacitors and ionozed the gas in the flash tube upon fireing.Trugger voltage has nothing to do with the battery voltage or the AC voltage in units that operate on thsoe power sources.

BebuLamar

Not really but I run into problem with some low trigger voltage flash that doesn't drop the trigger voltage when shorted together by the camera sync contact. Of course a dry contact would short it down to 0 volt but if a camera has an SCR for the flash sync circuit and voltage doesn't drop it continues conducting after the gate voltage is off. So the flash would fire the first shot then quit firing. Turning the flash off then on would make it fires again for another shot.

stu352 Loc: MA/RI Border

I still have my ancient Vivitar 283 flash from the '70's. I don't remember the exact voltage, but I think I saw a couple hundred volts on the contacts. No way I'm connecting that to any of my modern stuff, no matter what their specs say.

BebuLamar

I bought a 283 from estate sales and mine was an early unit made in Japan and has trigger voltage of 280V as I measured it.
Newer 283 made in China has less than 12V trigger voltage.

Screamin Scott Loc: Marshfield Wi, Baltimore Md, now Dallas Ga

The newer flashes that are dedicated to a brand will normally be safe. That said, TTL circuitry will not communicate properly with digital cameras

E.L.. Shapiro Loc: Ottawa, Ontario Canada

Old flash units can be dangerous- for sure! Even in the olden days of film cameras, they were known to harbor high trigger voltages and currents that would burn out the synch contacts in shutters. The contacts would fuse together, arc over, carbonize (blacken), and/or break off.

The old units could also deliver a nasty shock to the photographer if a synch cord was employed and the polarity was accidentally reversed. The metal camera body would become "live" with the positive side of the circuit- you could feel a "slight buzz" but if you came in contact with the negative side or walked over a high potential ground like a puddle of water or wet ground, you could sustain a nasty whack!

So...if you have or find an old flash unit- test it for trigger voltage. OR simply do no use it on your camera! You can purchase a simple photoelectric cell and use it for a second flash OFF CAMERA.

Old flashes can shock you twice- once with a nasty jolt and then with a shocking repair or replacement bill for your camera!