Tuesday, 23 April 2013

Beware of the flash trigger voltage

If you are going to use a flash other than the original Nikon flashes with the Nikon V1/V2 cameras with the help of my adapter then you must make sure that the flash you are intended to use is suitable for the purpose and won't fry your camera. Please note that Nikon does not publish the maximum allowable trigger voltage, so it is an intelligent guess that you should not exceed 12V. This is based on my own tests since my old flashes have a diversity of trigger voltage and the highest I used on the V1 has 12V. It is an old Olympus T32 flash, and while it is from the late 1970's, it does not mean that every flash made after that date is safe. Olympus was early in using low trigger voltage, most flashes from that age and even long after that, used high voltage which may cause harm to many modern digital camera, so it is entirely up to you to check that the selected flash has safe trigger voltage level.


How to measure the flash trigger voltage

To check the trigger voltage is very easy. All you need is a digital volt meter. One terminal must be connected to the ground contact of the flash and the other to the center pin, the actual trigger signal. After that the flash must be turned on and the increasing voltage should be monitored. Once the flash is fully charged the voltage should stabilize around the final trigger voltage. The displayed value should not be higher than 12V. I don't know what is happening if it is higher and I am not willing to try at this moment, all I know that my flashes have a large variety, from 5V to 350V, so if you just pick any flash you might end up with the same variation.


Four of my flashes as examples

The lowest trigger voltage has the Osram VS280 Studio which has 5V and is safe to use. The age of this flash is unknown, but I am guessing it isn't very old.

Next is the Olympus T32 which has 12V trigger voltage. It is from the late 1970's and in spite of the duct tape, I still use it fairly often.

The third is the Metz Mecablitz 30BCT4. The trigger voltage is over 150V, so I regard this unsafe, even though it is a very nice flash.

The fourth flash has even higher trigger voltage, almost 190V. It is the Sunpak Auto zoom 3000. It is very versatile but in direct trigger mode, using a cable, it is a NO NO.

I also have some other flashes which have even higher trigger voltages. Of course, these flashes can be used if you are using a radio trigger with a receiver which can trigger high voltage flashes. 

Please note that all the modern flashes I know of have low trigger voltage and also of course, all modern Nikon SB flashes, like the SB-600, SB-900 also are safe to use.
It is very important that the trigger voltage is checked prior to using a flash with my adapter on the Nikon V1/V2 cameras. The adapters will contain a protection diode, but the best level of protection is your own carefulness. The diode I am using is a 33V zener diode. Why did I select 33V zener? Because that's what Canon is using in their hot shoe cables, and I figured if it works for Canon it works for Nikon also. In other words it is just a guess from my side, so measuring the trigger voltage of unknown flashes is an important safety measure to avoid accidents, and the only thing I know for sure is that 12V (or less) trigger voltage is safe.