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10-16-2009, 06:45 PM   #1
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Old flash with DSLR question

I have Vivitar Electronic Flash 2000 that I used with my film camera. I tried it once on K20D and it worked but then I read on forum that old flashes should not be used with digital cameras because of high trigger voltage. I was lucky that I tried it only once and I didn't fry anything. So after long internet research I could not find the actual or even close trigger voltage of this particular flash and the K20D. So I am asking here if anybody has any information about this.

I shoot mostly in manual so I don't need expensive flashes with TTL or PTTL or whatever they come with.
I use it with longer exposures that allow me enough time to trigger the flash manually by hand of camera but I am afraid to mount it again on K20D for shots that use short exposures.

10-16-2009, 06:52 PM   #2
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Why don't you measure it yourself?

If you don't have a digital multimeter, buy one. It's only a few dollars. If you haven't used one before, learn how to. The tool and the knowledge are useful in other applications as well.

I have an expensive multimeter used in the lab. But I also have a few of these ($2.99 a copy) laying around the house, in the garage, in my car, in my office just in case:

7 Function Multimeter



To measure the trigger voltage, set the multimeter to measure 1000V DC (or any value above 300V), let the flash charged up, apply the ground probe to the connector on the side of the flash's hot foot, the other probe to the center pin of the flash's hot foot and read the value on the multimeter.
10-16-2009, 07:03 PM   #3
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Thanks for your answer SOldBear, I will do that.

But I still need to know the maximum trigger voltage for k20d, I can't find accurate information anywhere, just some guesses with very big differences
10-16-2009, 07:13 PM   #4
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By the way this flash has sync cord if that makes any difference.

10-17-2009, 12:18 AM   #5
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QuoteOriginally posted by Nelepl Quote
But I still need to know the maximum trigger voltage for k20d, I can't find accurate information anywhere, just some guesses with very big differences
I don't think Pentax has ever officially stated the max. trigger voltage allowed.

There is an ISO standard that calls for 24V max. But Pentax has never stated that they complied with ISO standards.

Different people have different ideas about trigger voltage. I myself feel comfortable with anything 12V or less but use 25V as the limit. I have used flash units up to 24V (Metz 45CT4) with my K10D bodies for an extended period of time without any problem.

BTW, Ricoh officially states 20V in the GX200 user's manual.
10-17-2009, 01:01 AM   #6
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I've had some success mounting an old Incablitz off-camera (ie on a bar that clamps to the tripod thread, rather than mounting the flash directly on the hotshoe). If your flash allows it, you can fire it via the K20's built-in flash, which will go off a fraction of a second before triggering the externally-mounted flash. The instruction manual will tell you how to set it up and it's safe because you've isolated the flash from the camera. For your use, it may be accurate enough.

By all means measure the trigger voltage of your flash, as SOldBear suggests - it's easy enough to do - but frankly I wouldn't go playing around with your precious K20D unless you're 100% sure you've nailed the numbers.

Last edited by Wombat; 10-17-2009 at 01:10 AM.
10-17-2009, 04:12 AM   #7
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Now you guys have me worried. I recently picked up a Pentax AF280T, which just arrived, based on recommendations in a thread on this site. Is it safe to use with my *ist DS?

10-17-2009, 05:20 PM   #8
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I called Pentax support when I got my K200D to inquire if I could safely use my old AF200S from my ME Super. They told me any of the old Pentax brand flashes are safe to use with any Pentax DSLR's.
10-17-2009, 09:44 PM   #9
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I agree with SOldbear, you should measure the trigger voltage. I don't think you can do it with a DMM though. The signal is only there for a very short duration and the digital multimeter averages the signal over time. The voltage spike from the flash wont be long enough to register. You need to measure it on an oscilloscope. Not that many people have one of those on the shelf....
10-17-2009, 11:12 PM   #10
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@RayMeedc: I measured my AF280T at 8 VDC trigger voltage. It won't be a problem using this very good old flash.

Jack
10-17-2009, 11:35 PM   #11
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QuoteOriginally posted by mr_tim34 Quote
I don't think you can do it with a DMM though. The signal is only there for a very short duration and the digital multimeter averages the signal over time. The voltage spike from the flash wont be long enough to register.
This is new to me. I don't know the theory. I just measure the voltage after the flash is charged up. Some of my flash units have trigger voltage of more than 200V, some as low as 3V.
10-18-2009, 10:09 AM   #12
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Those Cen Tech DMMs are garbage. My dad keeps buying em cause they're cheap. I used 2 of em to try and measure an alternator's output, and they wouldn't work.

Heck I went to use mine to measure a flash and the battery died. The 9V it uses is more expensive than a whole new unit.

Photo Strobe Trigger Voltages is a list of flash voltages and how to measure them. Is this is a sticky anywhere on PF?
10-18-2009, 11:54 AM   #13
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My friend is electrician and he told me that I can't measure this with multimeter because the signal is too short, so i didn't even go to get one.
10-18-2009, 03:28 PM   #14
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You don't need any special equipment. Just measure the voltage between the center pin and the side ground. Be sure the flash batteries are fully charged. That is the voltage you go by for use.
10-18-2009, 03:45 PM   #15
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If it's the model 2000 listed here: Photo Strobe Trigger Voltages

then, no it won't work. Test it to be sure with your model.
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