I have an NEX-6 and I wanted to use an external flash connected to the hot shoe. I have a canon speed light 580EX

I was told I may need to watch out for the different voltages, as the flash may operate at different voltages and harm the camera.

I should be able to find the operational voltages for the speedlight (if you know any good resources that would be great)

But, I cannot find the safe voltage for the NEX-6.

As a last resort, is there a way I could measure this with a test meter?


Modern flash units from recognizable manufacturers rarely use camera-damaging trigger voltages, so you don't need to worry about the 580EX.

Once upon a time, the flash trigger transformer's primary voltage (several hundred volts) was directly switched by contacts in the shutter in order to generate the 4000 or so volts the flash tube needs to have in order to trigger a flash. This is what would kill a modern camera.

A modern flash uses generally logic levels (~6V and under) to both trigger and communicate with the camera.

You can check here for a partial list of safe/unsafe strobes as of 2004. Another, more up-to-date source is here. I'd say a trigger voltage over 5 volts would be questionable for any digital camera.

Oh yes... Here is how to check your speedlight trigger voltage if you're still curious.

  • So I only need to worry about the voltage on the external flash being ~6V and under? - I assume all camera bodies are similar then (modern ones) Jan 17 '13 at 15:17
  • Generally speaking, 6v and under is fine, 10v and over is cause for more research. You can use something like this: bhphotovideo.com/c/product/245292-REG/… if you need to use an 'unsafe' strobe...
    – BobT
    Jan 17 '13 at 18:20

Someone has reported that, speaking with Sony tech support, they were told the voltage limit is 24V.

The majority of digital cameras today actually have sync voltage limits higher than you'll find from most online sources, since most online "folklore" about sync voltage limits comes from the botzilla page. What most folks don't realize is that that page was created around 2006, and is discussing the Canon Powershot G, and the first generation of Canon dSLRs. After the original dRebel (300D), the sync voltage on the hotshoe of Canon dSLRs was raised from 6V to 250V. Nikon dSLRs have a limit of 250V. Pentax has a limit of 25V, Panasonic reports 15V but Olympus says 24V--and four-thirds/micro four-thirds hotshoes share the same design, so go figure, there.

Generally, you don't need to hold to the 6V and above is dangerous thinking, and getting a safesync if you thought you measured 7V on the flash. Most digital camera hotshoes have a limit of 24V or higher.


As @bob says, 5 volts is about the warning area. The 580ex is modern, so you have no worries. Older electronic components were designed for as 5 volt logic, there is a bit of variance allowed, a half or maybe a full volt. After about 6 volts, I start to get nervous.

I have an original 1970s vintage Vivitar 285, which still works, but will fry any modern computer controlled camera without a safety device.

There are not a lot of gray areas to worry about. The old devices had trigger potentials of several hundred volts. Modern ones have trigger potentials typically of 3 to 5 volts. There is not much in-between.

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