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Showing posts 1 - 9 of 9, (reverse)
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05/30/2008 07:04:15 PM · #1
recently using my canon 5D and 580EX11 in e-ttl mode I was unable to freeze the action of Dancers on stage.
with my old manual flash this was not a problem any suggestions on how to overcome this situation. I am not concerned about the background just the subject.
05/30/2008 07:09:30 PM · #2
Did you set it to high-speed sync? This would allow you faster shutter speeds (but also use way more battery power).
05/30/2008 07:13:05 PM · #3
No I have not tried that, but I will. battery power is not a problem as long as I can get the shots I require.
thanks
05/30/2008 07:18:04 PM · #4
Do you have any samples you can show? Depending on the speed of the action you maybe having an issue many sports photographers have with the preflash lighting the subject and then the main flash going off, causing ghosting of the image. Essentially you get two stop actions very close to each other.

Matt

BTW post a sample and exif information for the best help.

05/30/2008 08:32:16 PM · #5
FP or high speed sync will cause the problem not fix it.... to get over the full open, it pulses the flash causing multi exposures of a moving target. Keep below your max sync 200 or 250 on that 5D I forget.

Edit: I always thought the eTTL preflashes were before the iris opens??? Curious what the issue with preflash is?

Message edited by author 2008-05-30 20:33:48.
05/30/2008 10:54:45 PM · #6
Yes please. Pictures with EXIF data intact. Or tell us what settings were at.

I would set it in manual mode at your sync speed (1/200) wide open and let the flash fill in. Or set to Hi-Sync and shoot at 1/1000 or something.
05/31/2008 07:15:07 PM · #7
Originally posted by robs:

FP or high speed sync will cause the problem not fix it.... to get over the full open, it pulses the flash causing multi exposures of a moving target.

Are you sure about this? A target would have to be very fast to move significantly in let's say 1/1000s... And if it did that, it would move even farther in 1/250s...
05/31/2008 08:41:18 PM · #8
Yeah pretty much.. but I might be wrong :-) With non FP the flash fires once (duration changes based on power needed but it's a single pulse)... with FP it fires multiple times to illuminate as the pair of curtains move across, so instead of a single frozen snap you get several. Not sure of the speed of the pulses but obviously they are quick, so the subject would have to be far from static... not sure of the speed required to see it.

Edit: Yeah, just did some google to confirm (if you can believe stuff on the web :-)...

Message edited by author 2008-05-31 20:44:27.
05/31/2008 09:54:51 PM · #9
The site you linked to mentions a pulsing rate of 50 kHz, which would mean 50 pulses during 1/1000s, right? This is pretty damn fast, so this is nothing you will see in the picture.

The site also says that FP is not suitable to freeze motion. I don't understand why. If the shutter is only open for 1/1000s, I don't care if my flash is already firing before and/or still firing afterwards. Well, I'll have to try this out.
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