Well, you should! Because it could be killing your camera!
If you like to mix old and new technologies, you may want to put that 1980's vinatge camera flash unit on your 1990's vintage camera or even on spanking new digicam. Well, before you do, you need to know the trigger voltage of your flash. If you disregard, you may fry your modern camera leading to an expensive repair.
In this Instructable, we will learn how to measure the trigger voltage of your "hot shoe" flash unit and determine if may damage your sophisticated camera.
Step 1: Why Should I Care?
What is trigger voltage? This is the voltage applied to the gas in the flash tube that ionizes that gas. Once ionized, the gas is able to conduct electricity and an incredible amount of electricity is discharged from the main flash capacitor into the gas tube producing a large amount of light. This light exposes Grandma Sue with exactly the correct amount of light to produce a great picture.
Why is high trigger voltage bad? Well, it is not bad intrinsically...the flash really does not care what voltage it is triggered at as long as it does the job of ionizing the gas. The bad part comes comes from how the flash is triggered. Mechanical systems simply close the circuit on the flash mechanically. Modern cameras will close the circuit through electrical means. If the voltage is too great, some will leak into the camera's circuitry and potentially damage electrical components. This damage may happen gradually and you camera may function for a while using the high voltage flash and suddenly die. Another failure mode is when the electricity arcs across the contact gap and erodes the contact or produces insulating products that cause the contact to fail.
How much is too much trigger voltage? For modern cameras, 6v or less is generally considered safe. 6v to 25v is a gray area that may or may not be safe for your camera depending on the make and model.
How do I tell if my camera is, "modern?" If your camera is digital, it is modern for the sake of this Instructable. For film cameras, it gets a little tricky. Going by manufacture date, cameras built before 1990 are probably more mechanical and should be safe with high trigger voltages. Any camera built after 1990 should be considered modern.