Damn high speed sync
/forum/topic/696290/0

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Photofiend4
Registered: Jul 01, 2008
Total Posts: 151
Country: United States

So I bought a 580 ex a while ago thinking hey this will go perfect for getting some fill flash in my skate sequences (30D 5FPS) WRONG. It's worked great for lighting indoor situations with its little built in white card, but I finally got some skate shots in yesterday and was sadly disappointed to find that with high speed sync it fires on the first shot and then quits for the entire 12 picture sequence (at least in RAW). Is this what I should have expected or is there something I am doing wrong?



turnert
Registered: May 19, 2004
Total Posts: 2811
Country: United States

Your flash can't recycle fast enough to keep firing while you mash down the shutter at 5 fps. If your aperture, distance, and ISO are such that the flash only needs minimal power for each frame, you can probably get off a few shots. But under normal conditions, even without high speed sync, the recycle time is longer than the frame rate.

~Ted



farley
Registered: Jan 26, 2003
Total Posts: 967
Country: United States

That is what you should have expected. There are a number of external battery packs that will decrease the recycle time, but even then the best you will probably get is two or three frames. Not only that, but in high speed light will not get out there very far.



simon_says
Registered: May 22, 2006
Total Posts: 812
Country: Canada

I doubt you'd find many (if any!) flash units that can cope with such high firing rate. Even if you could find a way to force it, you'd end up destroying them by burning them or have them melt!!!



Photofiend4
Registered: Jul 01, 2008
Total Posts: 151
Country: United States

Too bad. Looks like I'm gonna stick to shooting in raw and doing local adaptation.



Suparman Widja
Registered: Feb 21, 2007
Total Posts: 67
Country: United States

Hmm. Why not use 2nd-curtain in this case? You can also bump up the ISO so the flash does not have to consume that much power (and recycle faster).



krementz
Registered: Oct 31, 2004
Total Posts: 991
Country: United States

Suparman Widja wrote:
Hmm. Why not use 2nd-curtain in this case? You can also bump up the ISO so the flash does not have to consume that much power (and recycle faster).



2nd curtain has nothing to do with the OP issue. You can't 2nd curtain with high speed flash, anyway

Reducing the amount of power the flash needs, (higher ISO) will help, but not solve the issue. Banging off a dozen flashes at full speed - I doubt any camera mounted flash can do this - and especially at hi-speed sync.

You might try shooting at the synch speed and give your flash a better chance of catching up. PRobably will give you toomuch motion blur.



genoph
Registered: May 09, 2008
Total Posts: 663
Country: Canada

I found the 580 EXII could pop off five or so at 6.5 FPS before tiring out. just as fill though



Gochugogi
Registered: Jun 25, 2003
Total Posts: 7102
Country: United States

High speed sync vastly reduces power as it's a rapid pulsing of the flash. If it actually fired at fully output, you need 6 seconds to recycle, even with fresh batteries.

If the flash is the main light (weak ambient), try a long shutter speed with the flash in strobe mode. I used to do this with film and would get half a dozen sharp images on a frame.



Mark Peters
Registered: Nov 29, 2005
Total Posts: 2635
Country: United States

I had a big metz unit (Mecablitz 60 CT-4) that had a winder (2 fps) and motor drive (6 fps) mode. It was incredibly low power however.

Heavy and awkward for sports, but it has the feature you're asking about.

http://www.metz.de/fileadmin/fm-dam/Download/Photo_Electronic/Bedienungsanleitung/mecablitz/mecablitz_48_bis_76/mecablitz_60_CT_4_D_F_NL_GB_I_E.pdf

No idea if you will end up with a dark band if you try shooting at faster than say 1/320th.



Photofiend4
Registered: Jul 01, 2008
Total Posts: 151
Country: United States

Wow. That's a crazy flash.



Gil_W
Registered: Sep 30, 2004
Total Posts: 1899
Country: United States

By using the Cannon battery pack, I found the 580EX can do fairly good keeping up when shooting a burst with the lower fps rate of the 40D but not too well at the faster fps.

Gil



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