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Strobe Light with no Shutter


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#1 Eduardo Mayen

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Posted 11 September 2005 - 10:57 PM

I'm planning on shooting a fantasy sequence in a movie with a strobe light. I thought of completely removing the shutter and letting the strobe be the shutter itself and determine the exposure. What do I need to take into consideration? what would be the ideal speed for the strobe? (1/48th of a second?) How do I set exposure? Can it be done with an SRIII? Many questions. Thank you for any help.

Edited by Eduardo Mayen, 11 September 2005 - 10:58 PM.

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#2 David Sweetman

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Posted 12 September 2005 - 12:03 AM

That's crazy. Anyway I may be wrong but I think any professional around here would just tell you to test it.
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#3 Dimitrios Koukas

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Posted 12 September 2005 - 02:46 PM

I'm planning on shooting a fantasy sequence in a movie with a strobe light. I thought of completely removing the shutter and letting the strobe be the shutter itself and determine the exposure. What do I need to take into consideration? what would be the ideal speed for the strobe? (1/48th of a second?) How do I set exposure? Can it be done with an SRIII? Many questions. Thank you for any help.

<{POST_SNAPBACK}>


Eduardo,
1/48 in the strobe, doesn't match with the 24 fps, even that we set the photometer at 1/48sec. This is with the shutter on.
When the shutter is off , imagine that u will have a negetive running without anything to block the light off, wich means u will also have upper and down frames overlapse.
1/48 speed in the strobe means double flashes at your actuall speed.
1/24 is the more accurate but with even that u will have frame overlapse.
U see the stobe will continue light your frame, even that u see it flash!
The shutter blocks away all the light so that's why we have frames
Do your tests, maybe you will like the result and maybe this is what you re actually need, so why not go for it? I am sure you knew all this, it's just I am doing your check list.
As for the photometer reading, either use a flashmeter, or just a photometer.
Both will see the strobe, if you set the strobe rate 1/48 or above.
Upper and down side overlapse is definately what will happen.
Dimitrios
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#4 Luke Prendergast

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Posted 12 September 2005 - 04:34 PM

With the shutter removed from a spinning-mirror reflex camera, of which the SR3 is an example, you will not see anything in the viewfinder.
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#5 timHealy

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Posted 12 September 2005 - 10:24 PM

This sounds like a great idea to play with, but you don't necessarily have to completely remove the shutter. You could still use a strobe AND shutter so that you may see what you are shooting if the strobe itself flashes faster than a normal exposed frame. Say if the strobe flashes for 1/500 th of a second. This is how they shoot commercials, and the juices of a fruit ripped open or the water from a showerhead is photographed crisp and clean. The camera still operates at 24 frames per second. But one exposes for the flash itself. The shutter may be open before and after the flash, but theoretically there is not enough light to expose and blur the image before and after. They make the lights you need: http://www.unilux.com/ if you go that route. Of course you can do some high speed stuff as well. You are not limited to 24 fps. You could also get a similiar effect by shooting with normal lights and making the shutter smaller to 45 degrees or less. But I know you know that.

If your strobe flashes for longer than 1/60 of a sec. and you wanted blurry images, then you may have to address the shutter issue, or use a camera that the shutter can open more than 180. I think Panavision 35 mm open to 210 or something like that.

However, the strobe will have to be synced to the camera so that the flash doesn't go off during the pulldown or you will get streaking. Or perhaps you may like occasional streaking.

You could also use a normal rock and roll strobe but it will not flash in sync with the camera. If you use a shutter it will roll in and out of sync with the shutter and expose brightly and then dim out to a point where it will get brighter again. And you may be exposing half or a quarter of the frame. See the end of Alien when Ripley tries to get in the shuttle to see strobes going in and out of sync with a shutter.

Another issue would be, is it worth the expense of taking out the shutter and having it put back in after the shoot. But that's up to you.

Like the man said. Test it!

Good luck.

Tim
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