External Flash Question

[skeuos]

Just took the leap and got my first dSLR (Pentax K100D Super) after several years of p&s cameras. My question is this - I already have an external hot shoe flash (Kalimar 175A, powered by 4 AA batteries) from my days shooting Minolta 35mm SLRs. It's a very simple flash, and I don't shoot much indoors, but when I do, I'd love to be able to use this flash. Is there any way to find out if the camera and flash are compatible, and will work without damaging each other?

I don't have the manual for the flash, and the Pentax manual only talks about using Pentax flashes (of course). The guys at the camera store let me hook up the flash to the demo K100D Super, and the camera fired the flash just fine when taking pictures, so obviously the right connections are being made. But I'm concerned about any ill effects over time. Or am I just being paranoid? Does anyone have any recommendations or know of any resources I could check?

Thanks, and Happy New Year! Be watching for some test pics over the next few days . . .

steve

[ncredneck]

I spent some time looking into this. Digital cameras use electronic circuits to trigger a flash. They are very sensitive to high voltages. Some digital cameras are rated to only 6 volts while others are said to be good to 24 volts.

Old 35mm cameras used switch contacts. They don't care much about the voltage.

Old flashes would sometimes have several hundred volts on the trigger contacts. That is guaranteed to burn out a digital camera's circuit. Newer flashes have low voltage inputs. (Vivitar has reissued their classic 283 and 285 strobes as 283HV and 285HV with less than 6 volt sync inputs. The originals used more than 200 volts!)

When in doubt, you can measure the voltage on your flash. You need a volt meter (DVM). Using fresh batteries, charge up the flash until the READY light comes on. To be safe, wait a little while longer. Then use the DVM to measure the voltage between the center pin on the hot shoe and the side terminal. If it is below 6 volts, you're good with any camera. If it is between 6 volts and 24 volts, check with your camera's technical support people. If it's above 24 volts, never let it near your digital camera!!!

[skeuos]

Thanks for the thoughts and explanations. Been meaning to update this thread for a while with the information. Figured there ought to be one more place on the web with this information somewhat centralized.

All I can add is this link:

http://www.botzilla.com/photo/strobeVolts.html

In case anyone has an older 3rd party flash, it shows some measurements of their trigger voltages. None of them are by the manufacturers, so take them with a grain of salt.

In my case, my flash has been measure at 4-5V, and also at 183V. Not exactly confidence inspiring. I need to get my hands on a volt meter.