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2C registration?


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#1 Hal Smith

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Posted 18 September 2006 - 02:19 PM

There have been recent posts questioning 2C registration. In your opinion, just how good/bad is the registration on a well maintained 2C? For instance: Good enough for background plates, single frame animation (assuming the suitable motor), etc. without using post wizardry to fix registration weave and/or jitter? Or good enough for live action only.
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#2 Rolfe Klement

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Posted 18 September 2006 - 05:05 PM

depends on final output format...

could be OK for background plates - I would not risk it for single frame animation (rather use a new digital camera D80 nikon or a canon)

thanks

Rolfe
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#3 Mitch Gross

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Posted 19 September 2006 - 11:17 PM

No way is it good for background plates. Unless you enjoy writing tracking software to with the drifting frame movement in multiple directions.
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#4 Rolfe Klement

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Posted 20 September 2006 - 02:56 AM

I disagree

We shot some stuff at 24, 25 and 60fps on a well maintained 2C then brought it in to flame at 2K

we did a stabilization test and we had 1 to 3 pixel drift (intermittently)

which means a 1/2000 to 3/2000 stability ratio

which should be fine on out of focus background plates - but depends on many things (output format, DOF etc)

thanks

Rolfe
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#5 Stephen Williams

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Posted 20 September 2006 - 06:46 AM

Hi,

A well maintained 2c can be perfect at 24fps when double exposed, however a pin registered camera is better if you scan. Telecine can sometimes favour a 2c!

A worn camera will not be steady, Test,Test,Test!

Stephen
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#6 Tim Carroll

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Posted 29 June 2007 - 01:58 PM

A well maintained 2c can be perfect at 24fps when double exposed

Stephen


Stephen,

I am starting to study and learn the Arriflex 35 IIC line of cameras and something I stumbled across in Jon Fauer's Arriflex 35 Book confused me. And your post above added to the confusion. As you probably know, I have spent the last two years learning everything I can about the Arriflex 16S, 16S/B and 16M cameras and their service, repair and maintenance.

The 16S or 16M has a similar bowtie shutter to the 35 IIC, and with the 16S or 16M each opening in the shutter exposes one frame of film and then the film transports when the shutter is closed, so two frames of film are exposed for each shutter revolution. In Fauer's book, on page 171, he states that with the Arriflex 35 IIC, "Incredibly, each frame of film is actually exposed twice, because there are two open segments. The film is quickly transported during the brief period of time it is covered by one of the two mirror shutter segments."

So, does the Arriflex 35 IIC double expose each frame of film as the camera runs at 24 fps? And if so, why? And how does double exposure of the film make the image more steady?

Thanks,
-Tim
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#7 Stephen Williams

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Posted 29 June 2007 - 02:13 PM

So, does the Arriflex 35 IIC double expose each frame of film as the camera runs at 24 fps? And if so, why? And how does double exposure of the film make the image more steady?

Thanks,
-Tim


Hi Tim,

I believe it does expose twice, I don't know why. I have used a 2c a few times but I am by no means an expert. In the pre Arri III days, people would always use a Mitchell for plates where possible. FWIW the steadiness of Arri III's varies too, they should always be double exposure tested at the same camera speed to be used for the final shoot.

Stephen
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#8 Dan Goulder

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Posted 29 June 2007 - 02:25 PM

A well maintained 2c can be perfect at 24fps when double exposed, however a pin registered camera is better if you scan. Telecine can sometimes favour a 2c!

Stephen, could you elaborate on this? I'm getting a certain amount of jitter on footage shot on a 2C and transferred on a Spirit. A camera tech has just checked out the camera, and claims the registration is solid. Is it possible that this jitter could actually be coming from the Spirit? Thanks.
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#9 Nick G Smith

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Posted 29 June 2007 - 03:04 PM

Hi Tim,

A 2C only exposes each frame once. With one revolution of the butterfly shutter 2 frames are exposed. I have a 2C and steadiness is very good for a camera without a registration pin - you have to make sure your top loop is correctly set - 15 perforations between mouth of mag and topmost movement of claw - springs on film gate are correctly set at the right tension and claw and gears are not worn or otherwise damaged.
Jon Fauers statement that each frame is actually exposed twice is incorrect.

Nick
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#10 Stephen Williams

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Posted 29 June 2007 - 03:12 PM

Stephen, could you elaborate on this? I'm getting a certain amount of jitter on footage shot on a 2C and transferred on a Spirit. A camera tech has just checked out the camera, and claims the registration is solid. Is it possible that this jitter could actually be coming from the Spirit? Thanks.


Hi,

A Spirit can be unsteady, there is a bearing in the 'gate' sorry wrong term that can stop turning. IMHO a Spirit is never perfect for multi pass work as it ignores the perfs, however it's very acceptable most of the time. I am not a big fan of stabilizing software as there is a resoloution hit.

When shooting with a Mitchell I often put a 15 second double exposure test on the front of the roll, then it's easy to see how good the Spirit is that day! A scan on a pin registered scanner is way better if you compare back to back.

I have seen a 2c produce perfect results on a Spirit, my theory is that the edges are being used by both camera and telecine, Aaton also makes use of the edge.

I think you need to view the test footage from the camera yourself.

Stephen
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#11 John Sprung

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Posted 02 July 2007 - 01:19 PM

Hi Tim,

A 2C only exposes each frame once. With one revolution of the butterfly shutter 2 frames are exposed. I have a 2C and steadiness is very good for a camera without a registration pin - you have to make sure your top loop is correctly set - 15 perforations between mouth of mag and topmost movement of claw - springs on film gate are correctly set at the right tension and claw and gears are not worn or otherwise damaged.
Jon Fauers statement that each frame is actually exposed twice is incorrect.

Nick

Nick has it right. There is no camera that exposes each frame twice. If you did that, you'd have double images. For instance, your hand might have 5 fingers when it's still, but 10 fingers when it's moving. That's what happened on a test I saw once of shooting at 48 fps and trying to double print frames rather than skipping them.

The source of the error is probably the black interruptor band that was painted on the mirror shutters of the Model I and some of the early II's. The idea was to reduce flicker in the finder by doubling the flicker rate. That turns out not to work unless the shutter opening and interruptor band are nearly the same size, which leaves you no light at all on a 180 degree shutter. You can pull the taking lens and inch the camera to see if the shutter has this black painted band, it's radial and maybe 5 - 10 degrees wide.

Two and even three blade shutters are used in projectors to increase the flicker rate. That works because projectors pull down in 90 degrees typically, leaving plenty of room for an equal size interruptor. Displaying each frame 2 or 3 times works fine.




-- J.S.
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#12 chuck colburn

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Posted 02 July 2007 - 02:24 PM

Magazine clutches can affect registration. If their lube is aging and drying up it can make for anything from torn perfs to overly tight take up wind that can stretch the film. Both of which are not a good thing for transfers or registration in rear projection.
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#13 Paul Bruening

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Posted 24 August 2007 - 05:43 PM

As I understand it Arri's achieve their steadiness by pulling the claw away from the film in two directions. So, it pulls away from the perf hole and then back. I read that someplace. I could be wrong. That's supposed to be the genius of German engineering... uber alas and all that rot.
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