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shutter angle and frame speed


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#1 Tuly Roy

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Posted 17 January 2007 - 11:48 PM

can anyone pls tell me how visible the difference will be when something is shot at 144 degree shutter angle ; 72 fps as opposed to 180 deg shutter angle ;72 fps?? also name of some films using this combination will of much help .

thanks
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#2 David Mullen ASC

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Posted 17 January 2007 - 11:56 PM

can anyone pls tell me how visible the difference will be when something is shot at 144 degree shutter angle ; 72 fps as opposed to 180 deg shutter angle ;72 fps?? also name of some films using this combination will of much help .

thanks


The question is confusing. Are you asking about the look of a frame rate or a shutter speed? Because you can't compare 72 fps to 180 degree shutter. That's apples and oranges. You can compare 24 fps to 72 fps at the same shutter angle... or 180 degrees to 144 degrees at the same frame rate.

In terms of 180 degrees versus 144 degrees, it is not a dramatic difference. The shutter speed is slightly shorter when closing down from 180 to 144, so the motion is slightly crisper, less blur per frame, and at low frame rates like 24 fps, the motion will look slightly more staccatto, strobey. But it's not significant and most people probably won't notice if you had to use 144 instead of 180 degrees. It starts to get more noticeable at 90 degrees or less.

Filmmakers don't switch from 180 to 144 degrees for an effect, but to solve a problem like shooting 24 fps while filming an NTSC monitor to reduce the size of the roll bar.
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#3 Tuly Roy

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Posted 18 January 2007 - 12:22 AM

The question is confusing. Are you asking about the look of a frame rate or a shutter speed? Because you can't compare 72 fps to 180 degree shutter. That's apples and oranges. You can compare 24 fps to 72 fps at the same shutter angle... or 180 degrees to 144 degrees at the same frame rate.

In terms of 180 degrees versus 144 degrees, it is not a dramatic difference. The shutter speed is slightly shorter when closing down from 180 to 144, so the motion is slightly crisper, less blur per frame, and at low frame rates like 24 fps, the motion will look slightly more staccatto, strobey. But it's not significant and most people probably won't notice if you had to use 144 instead of 180 degrees. It starts to get more noticeable at 90 degrees or less.

Filmmakers don't switch from 180 to 144 degrees for an effect, but to solve a problem like shooting 24 fps while filming an NTSC monitor to reduce the size of the roll bar.



perhaps i haven't put the question properly . i am not asking about the difference seperately . i want to know how the shutter angle and frame speed combination works. in slow motion how the change in shutter angle from 180 deg to 144 deg work. or if i want a more pronounced strobing effect is it advisable to keep the shutter speed at 24 fps?

thanks
tuly

perhaps i haven't put the question properly . i am not asking about the difference seperately . i want to know how the shutter angle and frame speed combination works. in slow motion how the change in shutter angle from 180 deg to 144 deg work. or if i want a more pronounced strobing effect is it advisable to keep the shutter speed at 24 fps?

thanks
tuly

oopss frame speed!!!
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#4 David Mullen ASC

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Posted 18 January 2007 - 12:36 AM

You have to separate the two issues mentally.

You choose a frame rate in order to create sped-up, normal, or slow motion. So 72 fps is a slow-motion effect when played back at 24 fps.

You choose a shutter speed shorter than 180 degrees when you want less motion blur per frame. The difference between 180 and 144 is not significant in look, but for example, you may shoot at 72 fps with a 90 or 45 degree shutter to reduce the blur per frame during the slow motion effect so you see moving objects more crisply.

I once saw a commercial of runners on a muddy track, feet splashing in puddles, shot at 500 fps with a 45 degree shutter. So the motion was very slow and every droplet of muddy water was very crisp as it flew through the air. But it took a s--load of light to compensate for both the high frame rate and the closed-down shutter.

If you want strobing motion but not slow motion, you'd use a normal frame rate but close down the shutter angle.
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#5 judy schulman

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Posted 16 January 2009 - 07:52 PM

when shooting in the states on 16mm at 500fps on the Photo-Sonics Action Master 3000, your shutter options are the following;

Mirror Shutter: 160º to 7.5º variable settings - (markings at 144, 120, 90, 60, 45, 22.5, 7.5)

if one is planning on shooting with 5K, 10K, and 20K units, will the image be at risk of flicker at any particular shutter angle? just not sure if shutter will come into play with this issue or not. anyone know?
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#6 John Sprung

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Posted 16 January 2009 - 08:51 PM

At 500 fps, you're well beyond the 120 light pulses per second you get from 60 Hz. power, so there's always the risk of flicker if the light source follows the power curve. Some people have even reported it with lower wattage incandescents. 5K and up incandescents should have enough filament mass to be OK. HMI's, you have to check the specs on the actual makes/models of ballasts you're using.




-- J.S.
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