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scott karos

Is shutter speed always double the frames per second?

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I was just watching some videos on a couple camera and the video mentioned that you should always set your shutter speed twice the number of frames per second.

 

So if fps was 30, then shutter would be at 60.

 

I had never heard of this rule. Is this true? Is this a common practice?

 

 

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That assumes a shutter angle of 180 degrees, like a perfect half-moon, so that within each fps duration the frame is exposed for exactly half the period, and covered for the other half. Film cameras historically had fixed shutter angles anywhere from 130 to 220 degrees, or variable shutters that could be adjusted right down to fully closed, while digital cameras with electronic shutters can theoretically be set to anywhere from 0 to 360 degrees.

 

180 degrees is a common shutter angle setting, but by no means a fixed rule.

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Dom, would you mind explaining the 360 degrees with digital capture?

I am an ignorant where video is concerned.

 

Honest, I live behind a shutter.

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The use of shutter angles in a digital camera with no mechanical shutter is only a mental trick for the operator and allows the shutter time to be synced to the frame rate, so if you select 180 degrees, then when you switch from 24fps to 48fps, the shutter time is automatically changed from 1/48 to 1/96 without you having to manually select the new shutter time.

 

So "180", "360", etc. are just virtual, not physical. 360 degrees, meaning the shutter is never closed, is basically no shutter, so 1/24 at 24 fps.

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I usually shoot with 180 degree shutter, but if I know the footage will be post stabilized (for example using Warp Stabilizer in AE) then I usually choose 90 degree angle to reduce motion blur which could otherwise lead to very distracting edge artifacts in stabilized footage.

for music videos etc. stuff the shorter shutter time could also be usable. in movies I think it's a bit worn off effect in most cases and is also a very bad substitute to ND filters because it causes very visible effect

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The use of shutter angles in a digital camera with no mechanical shutter is only a mental trick for the operator and allows the shutter time to be synced to the frame rate, so if you select 180 degrees, then when you switch from 24fps to 48fps, the shutter time is automatically changed from 1/48 to 1/96 without you having to manually select the new shutter time.

 

So "180", "360", etc. are just virtual, not physical. 360 degrees, meaning the shutter is never closed, is basically no shutter, so 1/24 at 24 fps.

Hi David

so if we have to get the effect that they achieved in 'Saving Private Ryan' battle sequences...where the bomb shell explosions show the stutter effect of the moving objects and an almost strobe effect of the soldiers running....which has been achieved by low shutter angle like 45 degrees or so on film cameras, how can we mimic this with our latest digital cameras. will changing the shutter to 45 deg in Arri Alexa give the same stutter..strobish effect. are there any other ways to create that effect with the digital platform during principal photography and post shoot. thanks for your time and energy which you infuse into this forum. thanks in advance.

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Yes, you can set the shutter on a digital camera to 45 degrees, or if shooting at 24 fps, you could select a shutter time of anything near 1/192, and get that effect.

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Yes, you can set the shutter on a digital camera to 45 degrees, or if shooting at 24 fps, you could select a shutter time of anything near 1/192, and get that effect.

Thanks a lot David !

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