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11-28-2007, 05:58 AM   #1
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Voltage and old flashes

I have breen reading lately quite a bit of threads dealing with the compatibility of old flashes on the Pentax K10D and K100D. I was thinking that it might be a good idea to post the voltages of those who has tested their old flashes so people can have an idea on how dangerous will they be for their cameras. I have an old thyristor flash that I didnt tested but I will do it tomorrow. Please, feel free to add any information regarding any compatibility issue between camera-flash. Thank you for reading

12-08-2007, 07:40 AM   #2
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Try this link - they list virtually every flash made and still updating.

Photo Strobe Trigger Voltages
12-08-2007, 11:52 AM   #3
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Personally, I wouldn't put much faith in a generic table like that, when it's so easy to just measure your flash yourself. The process:

1) If you don't have a voltmeter or multimeter, go to an auto parts store and get one. It doesn't need to be fancy, a $10 one will do. Here's an example:

(link)

2) The meter should have two test probes, a black and a red one. The meter itself generally has three sockets. Plug the black probe into the Common/Ground socket, and plug the red probe into the socket marked for volts (V). Turn the meter on and set it to the highest VDC range.

3) Turn your flash on (with it off the camera). Looking at the bottom of the hot shoe, put one probe on the pin in the center of the shoe and the other probe on the metal contact in the side groove of the hot shoe. Read the value off the meter. If it's less than 6V, no problem. If it's negative, just ignore the negative sign (you're just touching the ground probe to the powered contact, and vice versa). You don't need to measure the voltage while popping the flash.

And there you have it. Good numbers without having to assume that your flash is the same as someone elses.
12-08-2007, 06:36 PM   #4
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Thanks Jerry.
My old Sunpack Autozoom 3000 measured by myself at 180V.
The chart on the site had it measured at 246V.
So too dangerous for my K100D Super

12-08-2007, 06:57 PM   #5
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Wow, yeah, don't put that on your hot shoe. Although you could use it wirelessly off camera using optical or radio slaves. Or put it on a Wein Safe Sync and then put that in the hot shoe. I have one flash that puts out about 40V, the Safe Sync knocks that down to 6.0V. The Safe Sync only has the center contact though, so any extra pins for dedicated functions won't work with it.
12-08-2007, 09:22 PM   #6
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I've had problems with the Weins safe sync. Most of the time I can't get it to trigger the flash. I think it was on here that someone said that on the K10D, it pushes the contact ball too far up on the safe sync and breaks contact.
I was doing a shoot and ended up having to use a C* instead of my K10D. Bummer.
12-08-2007, 11:17 PM   #7
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Jeff, how do you use the optical or radio slaves.
Is it an expensive set up.
12-09-2007, 07:25 AM   #8
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Smokey:

I see what you mean about the Safe Sync not working on the K10D (I've never tried it, I always used my Ist DS with it). But the problem isn't the ball, it's that the K10D hot shoe won't let you push the Safe Sync far enough forward for the ball to drop into the center contact hole. If you put the Safe Sync in backward then it will work. However, none of the flashes I have can be mounted to the Safe Sync backward; they all have some extra plastic in the hot shoe side slots that prevents it. Although a few minutes with a thin file or hobby knife would probably take care of that. On the other hand, the foot on the Safe Sync appears to be solid aluminum, so you could take a file to the front edge and knock off enough so you can push it in properly. BTW, the Safe Sync I'm referring to is this one:

Wein | Safe-Sync Hot Shoe to Hot Shoe (SSHSHS) | W990560 | B&H

I've never used radio slaves myself, but you can read up on them on web sites like Strobist. They are relatively expensive. I occasionally use optical slaves like these:

Hama | Hot-Shoe Slave | HA-6967 | B&H Photo Video

You use the pop-up flash or a low power shoe mount flash as the trigger, mount your main flash on the optical slave (you can hand hold it, or put it on a light stand, or whatever), and when the slave detects the flash of light from the pop-up it triggers the flash that it's mounted on. However, thanks to the geniuses who gave us cameras that only provide P-TTL, this won't work on the K10D/K100D, because the flash on the optical slave will fire when the pop-up does it's preflash instead of waiting until the main flash. So if you are using either of those two, optical slaves don't work.

Unless your old flash is a really nice one and you really want to keep using it, I would think that instead of dropping $50 on a Safe Sync you'd be better off putting that toward a new flash. I've never used them, but there seem to be a lot of cheap ones on eBay with the Digital Concepts name on them. Or the new version of the Vivitar 285HV is safe for digital, but it's an old-school style flash (no dedicated functions) so it may not be your cup of tea.

12-10-2007, 04:13 PM   #9
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Thanks, Jerry.
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