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Shutter speed in terms of shutter degree


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#1 Stacy R Fillion

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Posted 22 March 2007 - 04:03 PM

Hello, Forgive me if this is common knowledge but I've been trying to wrap my head around this for awhile. I have a sony vx2000 (30fps) 29.97 to get technical. If i am filming at 30fps with a shutter speed of 60 what would that be in terms of shutter degree. Now if i crank the shutter speed up to 500 what would it be in shutter degree. Is there some sort of chart or formula that is available to figure this out?
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#2 Nick Mulder

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Posted 22 March 2007 - 04:26 PM

if you are filming at 30fps each frame is taking 1/30 of a second up - if each exposure is 1/60 of a second which is half of 1/30 then you are exposing 1/2 of the available 1/30 - ie. a 180deg shutter angle

Think of a film cameras rotating shutter and you'll understand how it works (180 is half of 360)

as for 1/500 shutter speed the math is as follows:

((1/500)/(1/30))*360 = 21.6 deg

((exposure time) / (period per frame)) * 360 = shutter angle
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#3 David Mullen ASC

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Posted 22 March 2007 - 04:34 PM

In film, it's all halves and doubles...

At 30 fps, with a half-circle shutter angle (180 degrees out of 360), then the shutter is open for half of 1/30th of a second, i.e. a 1/60th of a second shutter speed. Of course, a video camera doesn't usually have a mechanical shutter, it has an electronic one so there's no shutter "angle".

But close down the shutter angle by half again, from 180 to 90 degrees, and you cut the exposure time in half again, from 1/60 to 1/120 for a camera at 30 fps. 45 degrees would be half of that, 1/240. So 1/480 (close enough to 1/500) would be 22.5 degrees.

Or you could write it out something like:

30 (fps) x 360/180 = 60 (for 1/60th of a second shutter speed)

so if:
30 (fps) x 360/x = 500 (for 1/500th shutter speed)
then
x = 30x360/500 = 21.6 (so the shutter angle is 21.6 degrees.)
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#4 Stacy R Fillion

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Posted 22 March 2007 - 05:04 PM

Thank-you very much Nick and David for simplifying that for me. I love to learn new things.

Edited by S.R.Fillion, 22 March 2007 - 05:04 PM.

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