Measuring trigger voltage of old flash guns

[francis]

I have got some old flashes that I haven't dared to use on my D80 because of the risk of frying the electronics. How should I go about measuring the trigger voltage of the flashes? Is there power in the contacts as long as the flash is on, or will there only be power when it's on? If so is the only was to measure, to use an oscilloscope or some other sort of instrument that can store a pulse reading?

One of the flashes concerned is a Metz CT-45 with a homebuilt voltage restricting hotshoe (I got the flash cheap), which I don't trust without testing it first.

Francis

 

[footleg]

You can get a general idea of the trigger voltage using a simple multimeter which handles high voltages. Don't expect an accurate reading due to the effect of the meter on the value measured, but it will tell you if it is over the 6V that is the maximum many cameras are rated for. I have Metz 45 flashes, and they measure +400V so definitely high voltage triggers! I believe Metz have some sort of modular interface blocks which provide dedicated flash behaviour for a number of different cameras, but these are expensive and I only ever fire my Metz big guns from my Firefly II slave units which cope fine with the high voltages. The low voltage flash I mount on the camera measures around 6V (the flash has to be turned on and fully charged to measure the trigger contact voltage). I selected my flash from ebay listings and looked it up on the following website to get a rough idea of whether it was suitable or not: http://www.botzilla.com/photo/strobeVolts.html

 

[footleg]

I'm interested in the home built voltage restricting hotshoe you mentioned. I have been planning to make a similar device so I can attach any of my flashes to my camera hotshow via a cable for close up work. Can you post any details to the forum?

 

[francis]

I can't help you with the home built component as my friend built it before I got the flash. I could ask him tho, if he has a diagram. Wein have a clever device that sits on the hotshoe and has another hotshoe on top so that you can use any flash with your camera. I have seen them on eBay before, and I'm sure BHPhotovideo has them too. I measured my Metz flash and it read just under 5V, so it should be OK. Am still worried about frying my camera tho  . I also tested a small Jessops 200AB which I have previously used with my Pentax analog cameras with an infrared filter to trigger my Firefly II, and it was over 250V (and gave me an electric shock  ). I'm glad I didn't try it on my camera...

Francis