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Using strobes for Video Camera


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#1 sergio cassini

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Posted 19 January 2009 - 05:22 PM

Hello there,
I know this topic was discussed before,but only regarding the use of film cameras.
I am shooting a music video and the director wants strobes in it.
Is there anything i have to look out for when i am shooting 50fps or 25fps(prog. scan) on red cam,shutterwise/syncwise,when using strobe lights?
I know f.e. that when shooting interlaced,the picture looks like"cut in half".
can someone share their experience?
thank you
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#2 Kiarash Sadigh

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Posted 19 January 2009 - 09:12 PM

Hello there,
I know this topic was discussed before,but only regarding the use of film cameras.
I am shooting a music video and the director wants strobes in it.
Is there anything i have to look out for when i am shooting 50fps or 25fps(prog. scan) on red cam,shutterwise/syncwise,when using strobe lights?
I know f.e. that when shooting interlaced,the picture looks like"cut in half".
can someone share their experience?
thank you


Your safest bet is to use the type that allows you to manipulate the duration of the strobes...this is simply because you might lose part of the light cycle due to the shutter rotation etc..... I would look into Dataflash a 3500w fixture that allows you to prolong the light cycle the way you want.
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#3 sergio cassini

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Posted 20 January 2009 - 02:58 AM

Your safest bet is to use the type that allows you to manipulate the duration of the strobes...this is simply because you might lose part of the light cycle due to the shutter rotation etc..... I would look into Dataflash a 3500w fixture that allows you to prolong the light cycle the way you want.

Thank you Kiarash,
so basically the strobe flash should take longer than 1/50 sec.but doesn't t it have to be in sync then?
in a video camera there is no rotating shutter.does anyone no what happens when your of sync with the strobing lights?is it just not on the frame or does it show video scanning"artifacts"?
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#4 Chris Keth

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Posted 20 January 2009 - 05:04 AM

Thank you Kiarash,
so basically the strobe flash should take longer than 1/50 sec.but doesn't t it have to be in sync then?
in a video camera there is no rotating shutter.does anyone no what happens when your of sync with the strobing lights?is it just not on the frame or does it show video scanning"artifacts"?


If you're out of sync when shooting true progressive scan or film, the strobes will take up unequal parts of each frame's exposure time and the strobe will seem to vary in brightness.

Correct me if I'm wrong but I think your best bet would be to set the strobe duration for more than 1/24th of a second. That way you'll have the best chance to get a solid exposure of it, since the duration is comprising one whole exposure AND the time before the next exposure. The strobe will never get lost in between exposures like gunshots can when you're shooting film.
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#5 sergio cassini

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Posted 20 January 2009 - 08:08 AM

If you're out of sync when shooting true progressive scan or film, the strobes will take up unequal parts of each frame's exposure time and the strobe will seem to vary in brightness.

Correct me if I'm wrong but I think your best bet would be to set the strobe duration for more than 1/24th of a second. That way you'll have the best chance to get a solid exposure of it, since the duration is comprising one whole exposure AND the time before the next exposure. The strobe will never get lost in between exposures like gunshots can when you're shooting film.

Thank you Chris and Kiarash, I'll try that.the shoot is on sunday and i will post the result a.s.a.p.
cheers
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#6 Kiarash Sadigh

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Posted 20 January 2009 - 07:13 PM

Exposure time in a standard 24frame/sec or 24p in video with a 180 degree shutter angle is 1/48th of a second, so a 1/24th will cover for more than the duration of the open position, however even if you have the strobe at 1/24th of a second you're still dealing with two separate "pulsating" entities , it's like synchronizing two pendulums at the same time; even if they stay sync for a while they sure go out of sync and then back into sync again...in other words unless your strobing device is connected and synchronized with your camera system you will get out-of-sync eventually. Anyhow, i'd like to hear about your experience and learn more...
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#7 sergio cassini

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Posted 26 January 2009 - 04:56 AM

Exposure time in a standard 24frame/sec or 24p in video with a 180 degree shutter angle is 1/48th of a second, so a 1/24th will cover for more than the duration of the open position, however even if you have the strobe at 1/24th of a second you're still dealing with two separate "pulsating" entities , it's like synchronizing two pendulums at the same time; even if they stay sync for a while they sure go out of sync and then back into sync again...in other words unless your strobing device is connected and synchronized with your camera system you will get out-of-sync eventually. Anyhow, i'd like to hear about your experience and learn more...

hello kiarash,the shoot was yesterday and it was exactly as you discribed in your post.we didn't have a syncable strobe.we could only adjust the intervals and the brightness manually with two faders.so i checked the image on my viewfinder and the spark was adjusting the speed untill the flashes were in sync and we could shoot the sequence for as long as the flashes and the camera were in sync,wich depended on how good we matched the flashes/frames.if we were of sync the frame was only partially illuminated wich did look like a strange defect image.since it was a music video and we had only four shots with strobes it was o.k. to go for the much cheaper disco strobe than the expensive syncabale strobe.if you shoot longer scene i would recomend to go for the pro strobe.
pictures coming soon...
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#8 Kiarash Sadigh

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Posted 28 January 2009 - 04:52 PM

hello kiarash,the shoot was yesterday and it was exactly as you discribed in your post.we didn't have a syncable strobe.we could only adjust the intervals and the brightness manually with two faders.so i checked the image on my viewfinder and the spark was adjusting the speed untill the flashes were in sync and we could shoot the sequence for as long as the flashes and the camera were in sync,wich depended on how good we matched the flashes/frames.if we were of sync the frame was only partially illuminated wich did look like a strange defect image.since it was a music video and we had only four shots with strobes it was o.k. to go for the much cheaper disco strobe than the expensive syncabale strobe.if you shoot longer scene i would recomend to go for the pro strobe.
pictures coming soon...


yes, glad to hear you got through it successfully, looking forward to see the pics...
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Visual Products

Rig Wheels Passport

The Slider

Media Blackout - Custom Cables and AKS

Gamma Ray Digital Inc

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rebotnix Technologies

Tai Audio

CineTape

Broadcast Solutions Inc

Glidecam

CineLab

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