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2C with a 172º shutter


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#1 Tim Carroll

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Posted 19 September 2007 - 05:08 PM

Was looking at this 2C I have on my bench and measured the shutter and found it has a 172º shutter. I thought they all had 180º shutters (at least according to the American Cinematographer Manual). Of course Jon Fauer's book says they have 165º shutter, but he is talking about the cameras with an adjustable shutter, which this 2C does not have.

I know the 2C conversion to Techniscope (2-perf) uses a 200º shutter, but does anyone know if there is or was a standard for the camera with a 4-perf movement and an Academy gate? Or do they all vary?

Thanks,
-Tim
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#2 Nathan Milford

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Posted 19 September 2007 - 05:59 PM

A 172.8º shutter makes a 1/50s exposure at 24fps, mitigating flicker in 50hz systems

172.8º fixed shutter is standard on A-Minimas (except really early ones) and is a typical setting on any variable shutter system.
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#3 Charlie Peich

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Posted 19 September 2007 - 07:23 PM

Was looking at this 2C I have on my bench and measured the shutter and found it has a 172º shutter. I thought they all had 180º shutters (at least according to the American Cinematographer Manual). Of course Jon Fauer's book says they have 165º shutter, but he is talking about the cameras with an adjustable shutter, which this 2C does not have.

I know the 2C conversion to Techniscope (2-perf) uses a 200º shutter, but does anyone know if there is or was a standard for the camera with a 4-perf movement and an Academy gate? Or do they all vary?

Thanks,
-Tim


Tim,
I?ve not heard of a 172-degree shutter for the 2C in the States. It should be a 180-degree shutter or the 165-degree shutter for the ?variable shutter? model.

The 35-III and the 435 have mechanical shutter settings for a 172.8-degree shutter. (The 435 has a setting for the electronic shutter at 172.8 degrees on the menu.). This would be for shooting 24fps with a 50Hz HMI power supply.

Perhaps you have a 172.8-degree fixed shutter for a camera that was used exclusively in a 50Hz environment driven by a 24fps crystal motor????

Best bet would be to ask Axel B. or Arri in N.Y. and have them check a parts manual to see if Arri did offer a 172.8-degree shutter.

180-degree shutter at 24 fps 60Hz line frequency or 172.8 degree shutter at 24fps 50hz line frequency.

172.8-degree shutter at 24fps 60Hz line frequency with a crystal motor- no problem.

You?ll have all my printed material tomorrow!
Regards,
Charlie

(Nathan explained it 1st while I was typing!)
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#4 Tim Carroll

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Posted 19 September 2007 - 09:48 PM

Tim,
I?ve not heard of a 172-degree shutter for the 2C in the States. It should be a 180-degree shutter or the 165-degree shutter for the ?variable shutter? model.

The 35-III and the 435 have mechanical shutter settings for a 172.8-degree shutter. (The 435 has a setting for the electronic shutter at 172.8 degrees on the menu.). This would be for shooting 24fps with a 50Hz HMI power supply.

Perhaps you have a 172.8-degree fixed shutter for a camera that was used exclusively in a 50Hz environment driven by a 24fps crystal motor????

Best bet would be to ask Axel B. or Arri in N.Y. and have them check a parts manual to see if Arri did offer a 172.8-degree shutter.

180-degree shutter at 24 fps 60Hz line frequency or 172.8 degree shutter at 24fps 50hz line frequency.

172.8-degree shutter at 24fps 60Hz line frequency with a crystal motor- no problem.

You?ll have all my printed material tomorrow!
Regards,
Charlie

(Nathan explained it 1st while I was typing!)


Thanks Nathan and Charlie,

My gauge is not that accurate, and I'm always really paranoid about touching the mirror on a camera, so I'm sure it's actually 172.8º as opposed to 172º. And you are both right, the camera is set up for a 24Bs/50Hz pulse signal with the old style ARRI sync patch to a Nagra. (It has the five prong socket on the back of the camera with 24Bs/50Hz written underneath).

Does this mean the camera was made for the European market? But if so, wouldn't it be a 25Bs/50Hz set up, as opposed to 24Bs?

Where do they shoot 24 fps under 50Hz electric power?

-Tim
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#5 Stephen Williams

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Posted 20 September 2007 - 02:50 AM

Where do they shoot 24 fps under 50Hz electric power?

-Tim


Hi Tim,

Historically film used to usually be shot in Europe at 24 fps, with the advent of video post production & telecine transfers 25 fps became the norm.

Stephen
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#6 Tim Carroll

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Posted 20 September 2007 - 10:04 AM

Hi Tim,

Historically film used to usually be shot in Europe at 24 fps, with the advent of video post production & telecine transfers 25 fps became the norm.

Stephen


Thanks Stephen,

Okay, so what kind of issues are going to be created by trying to use this camera for shooting here in the States? Are there going to be issues with flicker when using HMI lights? Will there be issues of flicker when using any other kind of lights, tungsten, florescent, etc.?

And Charlie, when you say, "172.8-degree shutter at 24fps 60Hz line frequency with a crystal motor- no problem." are you saying the 172.8º shutter with just a 24 fps constant speed motor would be a problem? Is there something magical about putting a crystal speed motor on the camera that eliminates the flicker issue? Or are you saying that with a crystal sync motor I could adjust the speed more accurately around 24 fps to eliminate the flicker?

Any and all advice would be appreciated.

Thanks guys,
-Tim
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#7 Stephen Williams

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Posted 20 September 2007 - 10:11 AM

Thanks Stephen,

Okay, so what kind of issues are going to be created by trying to use this camera for shooting here in the States? Are there going to be issues with flicker when using HMI lights? Will there be issues of flicker when using any other kind of lights, tungsten, florescent, etc.?

And Charlie, when you say, "172.8-degree shutter at 24fps 60Hz line frequency with a crystal motor- no problem." are you saying the 172.8º shutter with just a 24 fps constant speed motor would be a problem? Is there something magical about putting a crystal speed motor on the camera that eliminates the flicker issue? Or are you saying that with a crystal sync motor I could adjust the speed more accurately around 24 fps to eliminate the flicker?

Any and all advice would be appreciated.

Thanks guys,
-Tim


Hi Tim,

If the motor is Cristal then 24 fps will be flicker free with florescent & HMI. If the motor varies in speed then flicker could be an issue with HMI & Fluorescent regardless of shutter angle.

No problems with tungsten.

Stephen
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#8 John Sprung

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Posted 20 September 2007 - 02:07 PM

I know the 2C conversion to Techniscope (2-perf) uses a 200º shutter, but does anyone know if there is or was a standard for the camera with a 4-perf movement and an Academy gate? Or do they all vary?

The other shutter angle they made, in the model I and the early II before the cardioid cam and dwell claw, was 120 degrees. Those are a real collector's item.



-- J.S.
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