Advice on External Battery Pack

canon400d · July 18, 2011

At the present time I am using my 7D with a Canon 580 EX ll. I find when I have the camera set on continuous the flash only fires once.
If I bought an external flash battery pack would this allow the flash to fire continuoisly?
Regards
Bob

pathfinder · July 18, 2011

The short answer is no, Bob.

The longer version is, it depends.

It depends on how deeply you discharge the capacitor with each flash. You are running on 4 AA drycells in your flash, AND even if your battery pack will power the flash fast enough , you will run into real heating problems. The flash tube is not designed for continuous flash duty, and if you try it, it will power itself down to prevent a meltdown, as is described in your manual.

Now..... if you shoot at a high ISO, say 1600 or so, you may get several flashes before the capacitor is drained, but you will not be able to shoot continuously even with the Canon CP-E4 battery pack. I have the CP-E3 and I like it a lot, because it really does shorten recycle times for candid flash, but it does not provide continuous duty flash output when you are using most of the output the flash is capable of. If you only ned 1/16th of normal output, then you will get several flashes before it runs out of juice.

Black Box makes power packs for external speedlites, but you do have to pay attention you can overheat your flash if you pop it too many times in a row without letting it cool off in between.

ziggy53 · July 18, 2011

2 weekends ago I did use a Canon 580EX (version I with a high-voltage external power supply) in that capacity and I shot around 450 images in about 21 minutes, no problem (ISO 800 and f4). (It was a "dollar dance" at a wedding reception. I just now counted the images.)

pathfinder · July 18, 2011

I think that is a good example of what I was talking about, Ziggy.

At high ISO ( 800 ) and with a large aperture, not that much light from your flash is needed. You averaged about 1 frame every 3 seconds, but that is not continuous flash one right after the other. 450 frames is higher than I would have guessed you would get before over heating.

Have you ever had your flash shut down in this kind of situation due to over heating??

ziggy53 · July 18, 2011

pathfinder wrote: »

... Have you ever had your flash shut down in this kind of situation due to over heating??

No, I've never had it shut down on me. (I gather that the 580EX version "II" shuts down more conservatively however.)

When I run the flash like that I'm very careful to smell the flash frequently and, when I detect any scent of "heating", I stop using that flash for a while.

canon400d · July 19, 2011

ziggy53 wrote: »

No, I've never had it shut down on me. (I gather that the 580EX version "II" shuts down more conservatively however.)

When I run the flash like that I'm very careful to smell the flash frequently and, when I detect any scent of "heating", I stop using that flash for a while.

Thanks for the advice Pathfinder and Ziggy. The reason I am asking is because on the telly I see photographers on the news using canon with I assume the 580 flash and their flash is firing continuously. These external flash's do have a cord connected to their flash.
I was aware of the over heating problem after reading the manual and I have been guided by not taking any more than twenty flashes.
I do a lot of rally photography and shooting continuously is a must. At night time I find the car is past and I end up with one photo as a result of the single flash.
Cheers
Bob

pathfinder · July 19, 2011

Shooting photojournalism with rapid sequence flash shooting at distances of 2 - 6 feet in daylight or indoors, is a vastly different situation than trying to light up a high speed race car at night in the dark at 10 to 40 feet.....

Just something to ruminate about.

2.8, 4, 5.6, 8, 11,16, 22 is not only 1 stop aperture differences, but each of those numbers represents one full stop of light difference for those numbers as flash to subject distances... eg moving the flash from 2.8 feet to 16 feet is five full stops of less light -

puzzledpaul · July 19, 2011

pathfinder wrote: »

... eg moving the flash from 2.8 feet to 16 feet is four full stops of less light -

Just wondering if this should be 5 stops?

Never done any night rally stuff, but have played around with the multi-flash option on my 550ex.
The limitations on frequency/power/no of flashes noted in the handbook made interesting reading at the time.

Wouldn't fancy being a driver with this sort of thing happening...

pp

pathfinder · July 19, 2011

Thanks Paul I left out the 8 foot stop, so yes, it should be 5 stops less light; that is even worse!!

I have edited my post to correct the error.

canon400d · July 20, 2011

pathfinder wrote: »

Thanks Paul I left out the 8 foot stop, so yes, it should be 5 stops less light; that is even worse!!

I have edited my post to correct the error.

Thanks once again Pathfinder. In actual fact I do find at night time rallies when the flash fires it usually results in quite a satisfying shot. I should also have mentioned that I do night car check rallies when I have to take photos of the driver and navigator when the car stops at a check point for a few seconds. This is when I require the rapid fire because once again I usually end up with one photo because of the very short time I have to capture the shot.
Am I able to do rapid fire shots with the 7D and the 580 ll? If this is possible how do I go about doing it and would my 40D be better than the 7D. for this job.
Thanks a lot
Bob

ziggy53 · July 20, 2011

An external, high-voltage flash power supply, like the Canon CP-E4, will certainly help your situation. Try to find a balance between ISO and image quality and recycling speeds.

A second camera body and flash-with-power-boost is also a good idea if the above is not fast enough.

pathfinder · July 20, 2011

My Canon CP-E3 works quite well, with almost instant recycle for a few frames if shooting higher IOSs, like 800+

If the Canon CP_E4 battery pack is not enough, some folk move to the "Back Box" Al Jacobs has supplied many pros with these for years.

canon400d · July 21, 2011

pathfinder wrote: »

My Canon CP-E3 works quite well, with almost instant recycle for a few frames if shooting higher IOSs, like 800+

If the Canon CP_E4 battery pack is not enough, some folk move to the "Back Box" Al Jacobs has supplied many pros with these for years.

Thanks Ziggy and Pathfinder I will certainly look into what you have said and I am sure this will certainly help my problem.
Cheers once again
Bob

Toshido · July 23, 2011

pathfinder wrote: »

2.8, 4, 5.6, 8, 11,16, 22 is not only 1 stop aperture differences, but each of those numbers represents one full stop of light difference for those numbers as flash to subject distances... eg moving the flash from 2.8 feet to 16 feet is five full stops of less light -

I was under the impression that light fell off in accordance to distance. So that double the distance equaled half the light. While apertures were a ratio of focal length to aperture area.

So a change from 2 feet to 4 feet would be one stop. 2 feet to 8 feet would be 2 stops, and so on. So 2 feet to 16 feet would be (2,4,8,16) would be four stops.

pathfinder · July 23, 2011

Somewhere I posted a thread here on dgrin about this topic. At home I would search the link down, but this is posted from my iPad in a motel room, so you'll have to google to find it.

Set up a flash, set to manual flash control, and meter the flash output at different distances. I thought doubling the distances would halve the flash, but what I measured was 2.8, 4, 5.6, 8, 11, and 16 feet. I used a Sekonic meter, my camera's meter, and a tape measure.

Try the experiment yourself, and see if I am incorrect.

ziggy53 · July 24, 2011

Pathfinder is correct, of course. Light emission tends to expand as a square of the distance. Exceptions are collimated light beams (and other focused light beams) and large light modifiers, including bounced light, at close proximity.

canon400d · August 25, 2011

ziggy53 wrote: »

Pathfinder is correct, of course. Light emission tends to expand as a square of the distance. Exceptions are collimated light beams (and other focused light beams) and large light modifiers, including bounced light, at close proximity.

Hi,
I have just ordered a CP_E4 battery pack for use with 580llEX. Can anyone please advise me on the following:-
1 Do I set my 7D on continuous when using this pack?
2. What are the best settings on the 580llEX.? I always use it on ETTL and second curtain sync.
Cheers
Bob

pathfinder · August 25, 2011

For shooting consecutively, but not high speed frame rate, just plug it in, set your camera in Manual mode ( not Av or Tv) with a shutter speed at about 1/160th, with the flash in ETTL. Use an ISO of 800 or higher, and a reasonable wide aperture. 2nd curtain synch is fine, that is where I leave my speedlites. You should find that you can shoot almost every second or so with your battery pack. Use Energizer Ultimate Lithium batteries, not standard carbon zinc AA's. They will last a very long time with your CP-E4.

If you want stroboscopic flash, one right after another as fast as the flash can go, read the flash manual that comes with the 580ex II.

canon400d · August 25, 2011

pathfinder wrote: »

For shooting consecutively, but not high speed frame rate, just plug it in, set your camera in Manual mode ( not Av or Tv) with a shutter speed at about 1/160th, with the flash in ETTL. Use an ISO of 800 or higher, and a reasonable wide aperture. 2nd curtain synch is fine, that is where I leave my speedlites. You should find that you can shoot almost every second or so with your battery pack. Use Energizer Ultimate Lithium batteries, not standard carbon zinc AA's. They will last a very long time with your CP-E4.

If you want stroboscopic flash, one right after another as fast as the flash can go, read the flash manual that comes with the 580ex II.

Thanks Pathfinder that is brilliant. I should have realised from your first post reply that I don't use continuous. I really appreciate those settings and can't wait to trying them out and seeing the results.
Cheers
Bob

Advice on External Battery Pack

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