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Slow shutter speed


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#1 Phil Beastall

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Posted 13 March 2008 - 08:58 AM

I'm hoping to film cars passing by at an extremely slow shutter speed to create results you could expect to achieve with stills photography with a shutter speed of 5-10 seconds or slower. Can you recreate this kind of look with video at all? We want to achieve the look of the car headlights rushing past as long beams of light.

Please see the attached link as a guide to what I'm after:

http://www.danheller...-nite-4-big.jpg
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#2 Hugh Macdonald

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Posted 18 March 2008 - 09:06 AM

I really can't imagine this kind of thing to be possible in-camera.

In post, though, sure. Although it'll be very slow to render...

What you'd need is a good optical flow solution that can do its own motion blur on images.

Because of the speed of the cars, you'd almost certainly want to overcrank the camera (not sure what you're shooting on... Your other thread mentions low budget.... I'm pretty sure that the Panasonic HVX200 can shoot at up to 60fps) to get more frames to help it along....

Then, if you give this sequence to your comping software (personally, for this kind of thing, I'd use Shake with the Furnace plugin (the Kronos node, in this case)), and tell it so speed up the footage by however much you wanted. You can also tell it how much to use for its motion blur. This will give you trails as if you've done a long exposure, but with the trails moving at the speed that the cars were moving at.
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#3 Michael Nash

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Posted 18 March 2008 - 04:43 PM

It depends on how you want time and motion rendered in the final image. Real time or time lapse? Smooth motion playback or "choppy"? Different techniques give you different results.

The physics of it are always the same; motion blur in camera is created by the shutterspeed of a single frame, and motion rendering is created by the frame rate. The slower the frame rate, the slower the shutterspeed you can use. But the slower the frame rate, the more motion rendering is altered. You end up with sped-up motion (time lapse), real-time but "choppy" motion, or something in between, depending on what frame rate you use for playback.

For a true slow-shutter time-lapse look you can use a DSLR and make an animation sequence at whatever playback frame rate you like. A random example I found on Youtube: http://www.youtube.c...feature=related

If you want to stick to the video realm you can use a camera that can undercrank, like the Varicam or the HVX200. But you'll be limited to the shutterspeed allowed by the frame rate, which will be significantly faster than your desired 5-10 second exposure (maximum 1/2 second exposure with the HVX at it's 2fps hack).

And of course if you want smooth real-time motion but with added motion blur, then you're talking about a post effect like Hugh described.
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