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Archive 2015 · Any on-camera flashes more powerful than 580ex?

  
 
Peterk78
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p.3 #1 · p.3 #1 · Any on-camera flashes more powerful than 580ex?


usuthu65 wrote:
Think about the physics. In a typical flash circuit, the fully charged capacitor is floating at ~300 V on its terminals. When triggered, it is connected to a step-up transformer moving the ~300 V on the capacitor terminals to a few kV, enough to overcome the ionization potential of the xenon gas in the flash tube and cause an arc. This produces the flash seen.

The capacitor provides a fixed impedance to the circuit, so a high voltage pack would indeed stuff charge into the capacitor fast (i.e. shorter time constant). But all this does is get one faster to a
...Show more

Which is why, when I plug a canon or pixel external power pack into my 580 EX II in the middle of a shoot, I don't have to stop down the lens or change ss. The flash output stays the same.



Jun 28, 2015 at 01:46 AM
woos
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p.3 #2 · p.3 #2 · Any on-camera flashes more powerful than 580ex?


molson wrote:
Does it use AA batteries? If it does, it must be huge...

A high-voltage battery pack ranges from 125v to 325v - that would require between 83 and 217 AA batteries.

AA batteries cannot sustain full voltage output for the length of time it takes to fully charge a capacitor (unless you use hundreds of them at once...)



There aren't any tiny packs with voltages that high. You'd need step-up circuitry. The highest voltage battery cells you can buy (note, I said that you can go go buy, not what some scientist somewhere made lol )are high voltage lipo cells (that are slightly higher, by like .1 or .2 volts, than normal lipo cells).

Let's call them 4.3v max. They of course droop under load, like everything does. You'd need *at least* a 30S battery pack to reach your 125 number. Let's say that you found some factory in China that was making cells that would make (and the packaging *would* be by hand, mind you) you some TINY lipo cells and charge you a bunch because packaging 30+ tiny tiny cells over and over would be really annoying....

Nah, you could I suppose go and buy some of the commercially available packs around that voltage (they do exist). Of course, they are more reasonably sized. They can be small, but even small packs like that weigh a couple pounds usually....not something you'd be carrying around for use on an on camera flash ... I found some 6lb 96v packs, there you go. Doesn't sound too portable to me though. ^_^

And of course, manufacturers selling stuff over .. ahh i forget where the cutoff is, but it's somewhere around 50v..maybe it's 60v? I forget... well, they are going to be paranoid about safety because once you get above about 60 or so it can penetrate dry skin on most people.

Anyway, no. And the circuit in the flash doesn't care if its input voltage is 1.2 or 1.5, as long as there is enough charge left in the battery to fill it. So this entire thing is moot. I just wanted to point out the ridiculousness of it. :P



Jun 28, 2015 at 10:32 AM
Mike Sowsun
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p.3 #3 · p.3 #3 · Any on-camera flashes more powerful than 580ex?


woos wrote:
There aren't any tiny packs with voltages that high. You'd need step-up circuitry. The highest voltage battery cells you can buy (note, I said that you can go go buy, not what some scientist somewhere made lol )are high voltage lipo cells (that are slightly higher, by like .1 or .2 volts, than normal lipo cells).

Let's call them 4.3v max. They of course droop under load, like everything does. You'd need *at least* a 30S battery pack to reach your 125 number. Let's say that you found some factory in China that was making cells that would make (and the
...Show more



The Canon CP-E2 uses 6 AA batteries and puts out 300 volts.

The Canon CP-E4 uses 8 AA batteries and puts out 300 volts.

There are also many third party packs that do exactly the same thing. They are all compact, light, and work very well for what they are intended.

From some of the posts here, it seems some people have no idea what high voltage battery packs are, and what they actually do.



Jun 28, 2015 at 11:20 AM
Shutterbug2006
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p.3 #4 · p.3 #4 · Any on-camera flashes more powerful than 580ex?


The CP-E2 and E4 do not 'put out' 300 volts. The voltage multiplying circuitry is in the flash body, not the battery pack.

The battery packs, regardless of number of AA batteries, output 6VDC if I'm not mistaken.

You can examine the schematic diagrams of a Canon 580EXII by downloading a service manual from this link.....

http://bit.ly/1NqIBrd



Jun 28, 2015 at 12:26 PM
Mike Sowsun
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p.3 #5 · p.3 #5 · Any on-camera flashes more powerful than 580ex?


Shutterbug2006 wrote:
The battery packs, regardless of number of AA batteries, output 6VDC if I'm not mistaken.



Sorry, but everything I have read on the subject says you are mistaken.

There is "voltage multiplying circuitry" in the flash, but it is also present in the battery packs.



Jun 28, 2015 at 02:17 PM
Shutterbug2006
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p.3 #6 · p.3 #6 · Any on-camera flashes more powerful than 580ex?


Mike Sowsun wrote:
Sorry, but everything I have read on the subject says you are mistaken.

There is "voltage multiplying circuitry" in the flash, but it is also present in the battery packs.


No way. That would make the battery pack extremely dangerous.



Jun 29, 2015 at 09:38 AM
Mike Sowsun
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p.3 #7 · p.3 #7 · Any on-camera flashes more powerful than 580ex?


Shutterbug2006 wrote:
No way. That would make the battery pack extremely dangerous.


Is that your "gut feeling" or do you have something to back it up with?

This is from page 4 in the Canon 580EX II Service Manual CY8-1201-307E




Jun 29, 2015 at 10:05 AM
anthonygh
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p.3 #8 · p.3 #8 · Any on-camera flashes more powerful than 580ex?


Think of a capacitor as a water tank with a ball valve, like a toilet uses...it can be filled with a trickle of water or a fierce gush.....but when it's full the ball valve closes the input source....trickle or gush, it's stopped dead.


Jun 29, 2015 at 02:15 PM
Shutterbug2006
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p.3 #9 · p.3 #9 · Any on-camera flashes more powerful than 580ex?


Mike Sowsun wrote:
Is that your "gut feeling" or do you have something to back it up with?

This is from page 4 in the Canon 580EX II Service Manual CY8-1201-307E
http://i2.photobucket.com/albums/y17/msowsun/photo%20stuff/photo16/_580exii.jpg


Turns out some battery packs have built-in converters that do output 300VDC to the terminal plug.

You're right, and I was absolutely wrong.

I for sure won't buy a made-in-china third-party flash battery pack for safety reasons.



Jun 29, 2015 at 02:58 PM
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