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Archive 2013 · Flash Duration to Freeze Action

  
 
gladivs
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p.1 #1 · p.1 #1 · Flash Duration to Freeze Action


Hello.

I'm using flash indoors for sports. Generally, the environments are generally a little on the dark side so typically I can use flash at lower powers (1/4 power-ish) and do fine.

I do occasionally find myself in a higher ambient setting where I need to push more light at the subjects to create a differential with the ambient light. I know that flash duration increases with the power settings. Is there a minimum duration that I should shoot for?

At full power, it looks like a Canon 580EX is around 1/285. I'm thinking that is too long a duration.

Thanks!



Nov 24, 2013 at 10:18 AM
P Alesse
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p.1 #2 · p.1 #2 · Flash Duration to Freeze Action


A lot of variables play into it. If bouncing, the duration slows a bit. Makes sense... it's bouncing all over the place and I'll get more motion blur. Direct flash is more apt to freeze action, but then you have the added variable of how much you want to overpower the ambient. More leak... more ghosting. Its a trade-off.


Nov 24, 2013 at 02:51 PM
timgangloff
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p.1 #3 · p.1 #3 · Flash Duration to Freeze Action


I'd say you want your flash duration times to be at least as fast as the shutter speed you would use to stop the action. For most sports, I'd say that about 1/500 is a good starting place. I don't really use on camera flashes to shoot indoors, but use strobes or use my 580ex in conjunction with the strobes. You are right, lower the flash power and get faster t times (flash durations), except with most strobes that get faster t times with increased power. The Buff Einsteins work more like flash guns and get faster with decreased power. Anyway, if you are trying to overcome the ambient with lower power, you'll just need more flashguns or strobes.


Nov 25, 2013 at 09:34 AM
Carl Auer
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p.1 #4 · p.1 #4 · Flash Duration to Freeze Action


At full power a 580 EX II is 1/833 seconds. Lower power shortens the duration. A mix of flash duration and power is what is important. A strobe with 1/20000th of a second flash duration does not mean a thing if you do not have the power to overcome ambient light.


Nov 26, 2013 at 03:05 AM
gladivs
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p.1 #5 · p.1 #5 · Flash Duration to Freeze Action


Thanks everyone. I use off camera, direct flash in these instances. Einsteins are on my list of things to get, but that is quite a bit in the future.

@timgangloff, I was wondering the same time regarding outdoor shutter speeds vs flash duration. I have this "1/1000 second" stuck in my mind, but really cannot find any reference. I've been trying to stay with durations faster than that but maybe will experiment a bit. The difficulty with experimenting is that I'm doing it at the event, and things like "ghosting" don't appear on every shot regardless of the flash duration.

#Carl - yes, I agree. I'm looking to see how long I can go on duration to figure out what power I'll have available to overcome the ambient. The 1/833 at full power is the only duration that Canon publishes for the 580EX II. It's assumed to be the t0.5 duration. I used the estimated t0.1 duration of 1/285 (3x the t0.5).




Nov 27, 2013 at 09:26 AM





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