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Old Jul 2, 2006, 10:33 AM   #1
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:?I have an old Vivitar 2800 Auto Thyristor Flash and a 20D. I cannot seem to make the sucker fire, but it may be some sort of setting I am not correctly errr.. setting.
- My brother with a 10D came by, and the flash fired fine on his rig.

- When I try firing it with my 20D, the 'amber' ready light actually blinks off for a second, and then blinks on. So some sort of sommunication is going on I suppose?
Any help would be appreciated.

Thanks! :?
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Old Jul 2, 2006, 10:40 AM   #2
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Hopefully, you didn't fry your camera.

Canon recommends using hotshoe attached strobes with trigger voltages of 6 volts or less, and that Vivitar has been reported to have trigger voltages upwards of 140 volts by some users.

I also see one mention from a user that says one wouldn't fire on a Canon G3. So, you may have the same problem on an EOS-20D. In any event, I don't think you want to keep trying it (unless you want to damage your camera). I'd also suggest you don't keep trying it on your brother's EOS-10D, unless you want to damage his camera, too.

Damage from excessive trigger voltage can be accumulative from what I've read (it may work to begin with and break the camera after more use).

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


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Old Jul 2, 2006, 11:07 AM   #3
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P.S.

You'll find some debate over what "should" be a safe trigger voltage for Canon models, since the ISO specifcations call for support up to 24 volts.

But, I certainly wouldn't use an old strobe with a trigger voltage of 140 volts, and if it were me, I'd stick to one that was less than 10 volts (preferrably less than 6 volts, since that's what Canon has told users in the past).

There are a number of newer Auto Thryistor strobes that are safe for modern digital cameras.

The Sunpak 383 Super is one popular model if you don't want/need a dedicated flash.


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Old Jul 2, 2006, 4:37 PM   #4
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I learned of high strobe voltages on this forumabout ayear ago. NHL pointed out that my old Sunpak 622 can be operated by three different batttery packs and the trigger voltage varies. He recommend a Wein Safe-Sync hot shoe attachment that limits voltage. I got one and haven't had any problems. It's not cheap - about 50 bucks - but less than a new strobe especially a larger one with a higher GN.
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Old Jul 2, 2006, 4:58 PM   #5
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ADSchiller wrote:
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It's not cheap - about 50 bucks - but less than a new strobe especially a larger one with a higher GN.
I dunno...

I've got some older Vivitars with trigger voltages that are too high for many modern cameras, and I decided to buy newer used strobes instead. ;-)

I payed a a whopping $25 for a Sunpak 333 Auto in 10 condition (as new in box) from the used department at B&H for a better unit (tilt, swivel, zoom head, multiple auto aperture ranges, manual power settings, etc.).

Then, I got a smaller Sunpak 222 Auto for $7 at keh.com, buying a third party adapter from a vendor in Hong Kong to give me an ISO standard hotshoe and PC Sync port (which can be used at the same time) for $16 delivered. Flash System Investment: $48 for two strobes and the hotshoe adapter (and keh.com even threw in a nice coiled PC Sync Cord with the little 222 Auto).

In a replacement for something like a Vivitar 2800, you could probably pick up a used strobe for about $10 (or less). The Sunpak 222 Auto I bought for $7 would be a comparable strobe.

Even a brand new strobe that's comparable would likely be under $50.00. For example, a little Sunpak 144 PC is only $39 brand new at B&H (roughly the same as the Vivitar 2800 with tilt and no swivel and only two auto aperture ranges). There's a slight difference in the GN (80 versus 66 feet at ISO 100). But, they're pretty close to the same.

Yes... If he had a more powerful and expensive strobe like your Metz 622, then it would make sense to get a Wein Safe Sync. But, for a strobe like the Vivtar 2800, it's probably cheaper just to buy another strobe, especially if you go used.



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