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#1 Tasha Back

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Posted 09 June 2006 - 05:55 PM

Hi there

Can someone tell me how I can get an effect of blurred motion shooting on 16mm film? Is this the effect shooting with a 45 degree shutter will create? In this case do I need to change the fps or just adjust for exposure on the lens? And if so by how much?

What is the difference in effect between changing the shutter angle and the "saving private ryan" technique? (I believe they changed the movement in the camera so the film was being pulled down whilst the shutter was still open to create a "strobing"...is that correct?)

Any help much appreciated!

Natasha
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#2 David Mullen ASC

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Posted 09 June 2006 - 07:25 PM

Closing down the shutter angle from 180 degrees to 45 degrees reduces the shutter speed, thus decreasing blur, not increasing it. At 24 fps, which is barely a fast enough frame rate to avoid flicker and look like continuous motion, fast motion tends to strobe as you become aware of the low number of frames that constitute the motion. So a 45 degree shutter angle makes this strobing problem much worse because you don't have enough blur per frame to help the illusion of continuous motion. Sometimes the look is called "pixellated" because it is similar to the problem of stop motion animation where there is no motion blur per frame.

Unfortunately, most film cameras cannot go much beyond 180 degrees to increase the blur. A Panaflex goes to 200 degrees, but that's hardly anything. A film camera needs the shutter to be closed long enough to advanced the film to the next frame before it opens the shutter again.

Video cameras allow you to switch off the shutter, so with most 24P cameras like the F900 or DVX100, you can shoot at 1/24th of a second at 24P, basically shutterless, and get twice the blur per frame compared to the normal 1/48th of a second used at 24P to emulate a 180 degree shutter (in a film camera, a shutter is an intermittant spinning half-circle, 180 being half of 360 degrees. So at 24 fps, the shutter is open for half that time, half of 1/24th, which is 1/48th.)

To really get more motion blur per frame, you have to reduce the frame rate, especially in a film camera limited to 180 degrees. For example, with a 180 degree shutter, at 6 fps, your shutter speed is 1/12th of a second.
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