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Mitchell BNC with 2 shutters, why?


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#1 Tim O'Connor

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Posted 01 January 2008 - 11:43 PM

I just watched the DVD about Stanley Kubrick and his career (sorry, I returned it to
the video store and can't think of the proper title.)

There's a story in there about how Stanley Kubrick obtained a Zeiss lens that
had been developed for NASA and could shoot at F.07 and he wanted to use it on
his Mitchell BNC (for Barry Lyndon I think.) The guy who modified the camera said
that it would be a challenge, although he was able to do it, because the camera has
two shutters and a thick aperture plate.

Why would it have two shutters? Are there other cameras that do also?
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#2 Jay Taylor

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Posted 02 January 2008 - 12:33 AM

Hey,

With two, the first one was a mirror shutter for the reflex viewfinder. Then behind that shutter was a focal plane shutter. I think?

This way you had a nice, bright viewfinder, AND you never had to worry about any light leaks. These cameras are great for live action, as well as time-lapse and stop-motion.

Hope that helps!


Jay
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#3 David Mullen ASC

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Posted 02 January 2008 - 12:53 AM

Kubrick's Mitchell did not have a mirror shutter. A Mitchell BNC had one variable shutter. The Zeiss lens that Kubrick purchased had a Compur shutter that had to be removed. The variable shutter in the Mitchell was replaced by a single blade shutter moved closer to the film plane, etc.

http://www.visual-memory.co.uk/sk/ac/len/page1.htm
For "CLOCKWORK" we purchased a standard Mitchell BNC for Kubrick and overhauled it, but did not reflex it or modify it in any special way. Kubrick's attitude has always been that he would rather work with a non-reflexed BNC and thereby gain tremendous flexibility and latitude in adaptation of special lenses to the camera - as was subsequently the case on "BARRY LYNDON". For "CLOCKWORK" w e also supplied the major accessory items for which we are well known, such as the "Joy Stick" zoom control, the BNC crystal motor and the Arri crystal motor.
At the very early stages of his preparation for "BARRY LYNDON", Kubrick scoured the world looking for exotic, ultra-fast lenses, because he knew he would be shooting extremely low light level scenes. It was his objective, incredible as it seemed at the time, to photograph candle-lit scenes in old English castles by only the light of the candles themselves! A former still photographer for Look magazine, Kubrick has become extremely knowledgeable with regard to lenses and, in fact, has taught himself every phase of the technical application of his filming equipment. He called one day to ask me if I thought I could fit a Zeiss lens he had procured, which had a focal length of 50mm and a maximum aperture of f/O.7. He sent me the dimensional specifications, and I reported that it was impossible to fit the lens to his BNC because of its large diameter and also because the rear element came within 4mm of the film plane. Stanley, being the meticulous craftsman that he is, would not take 'No" for an answer and persisted until I reluctantly agreed to take a hard look at the problem.

When the lens arrived, we could see it was designed as a still camera lens, with a Compur shutter built into the lens. The diameter of the lens was so large that it would just barely fit into the BNC lens port, leaving no room for an additional focusing shell. As a consequence, we had to design a focusing arrangement so that the entire lens barrel rotates freely in the lens port. To avoid possible binds that might result from this unconventional mode of operation, we added a second locating pin to the standard BNC lens flange, so that the two pins securely held the lens barrel concentric with the lens port during operation.

The problem of the close proximity of the rear element to the film plane was a much more difficult matter to resolve. To begin with, we removed the adjustable shutter blade, leaving the camera with only a fixed maximum opening. We then had to machine the body housing and the aperture plate a considerable distance inward so that the fixed shutter blade could be pulled back as far as possible toward the film plane.

Naturally, the Compur shutter had to be dismantled and the iris leaves altered so that they could be manually operated in the normal manner. Calibrating the focus scale on the lens presented quite a problem, too. A lens as fast as this has an extremely shallow depth of field when shooting wide open, so Kubrick understandably wanted to have as broad a band spread on the scale as possible. To do this we used an extremely fine thread for the focusing barrel and this resulted in a scale which required two complete revolutions to go from infinity down to approximately 5 feet. We had to stop at 5 feet or it would have taken several more revolutions to bring it to the near focus point. Kubrick agreed that this was as close a focus as he would require, and that stopping at two revolutions would make the scale less ambiguous.

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#4 Tim O'Connor

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Posted 02 January 2008 - 09:11 AM

Wow, that's great, thanks David. What a story. (Maybe this is obvious but it just occurred to me that
it's kind of funny that the director of 2001 used a lens for outer space to shoot a period piece
set before electricity was in use.)

I love these stories of how people adapt and machine stuff. It's so cool.


Jay, I didn't know about the mirror shutters that you describe that send that much light and no leaks,
thanks.
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#5 Stephen Williams

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Posted 02 January 2008 - 10:17 AM

Wow, that's great, thanks David. What a story. (Maybe this is obvious but it just occurred to me that
it's kind of funny that the director of 2001 used a lens for outer space to shoot a period piece
set before electricity was in use.)

I love these stories of how people adapt and machine stuff. It's so cool.


Jay, I didn't know about the mirror shutters that you describe that send that much light and no leaks,
thanks.


Hi,

Until the Mitchell MK II all Mitchells were light tight for animation. Early cameras were Rack Over only then came the BNCR. Many earlier cameras were converted for reflex viewing, not all conversions retain the variable shutter. Ones that do cannot use PL mounted lenses.

Stephen
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#6 Jay Taylor

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Posted 02 January 2008 - 01:00 PM

Hey,

Which Mitchell am I thinking of, with the mirror AND the focal plane shutter? Is that the s35?


Jay
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#7 John Holland

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Posted 02 January 2008 - 01:08 PM

Hi Jay yes you are correct thats the S35 .
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#8 David Mullen ASC

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Posted 02 January 2008 - 01:31 PM

The Mitchell S35R and the Mark III, according to the 1980 edition of the American Cinematographer Manual.
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#9 Leo Anthony Vale

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Posted 02 January 2008 - 02:50 PM

CSC in NYC and Technovision modified some BNCRs to be able to use Cooke lenses.
Technovision used the stremlined, white 200R model. a technician who had worked at Mitchell told me that they called the 200R the Technovison model, because Technovion had requested the make over, presumedly to have their cameras look more like a PSR.

Does anyone know what exactly the modification was?
Were both shutters replaced with a single mirror shutter ala Arriflex,
or was only the mirror shutter replaced?

& 'The Black Hole' article in AC mentioned that Disney had the shutter on at least one of their S35Rs to be able to accept Technovision lenses, which were mostly Cookes.
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#10 Stephen Williams

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Posted 02 January 2008 - 04:15 PM

The Mitchell S35R and the Mark III, according to the 1980 edition of the American Cinematographer Manual.


Hi David,

Due to bad design the S35R / Mark II is not light tight for animation. The MK III is a very rare beast I think only 2 examples survived, the original owners would not return them to the factory to be destroyed.

Stephen
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#11 Matt Kelly

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Posted 07 January 2008 - 02:21 AM

Really? Where's the light leak on a Mark II? I've never heard about it.
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#12 Stephen Williams

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Posted 07 January 2008 - 05:58 AM

Really? Where's the light leak on a Mark II? I've never heard about it.


Hi,

Light leaks through the register pin holes if you do Animation. A capping shutter is required for the MK II.

Stephen
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#13 Tony Brown

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Posted 19 February 2008 - 12:54 AM

Hi,

Light leaks through the register pin holes if you do Animation. A capping shutter is required for the MK II.

Stephen


Second that...... from experience. Nothing more boring than reshooting animation I assure you..... ALWAYS use a capping shutter.
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#14 Federico Vitali

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Posted 30 August 2008 - 05:26 AM

Hi,
Anybody knows how can I install a capping shutter on a MK II?...I would like to use my MKII for animation and, as I can read here, I can't without a capping shutter...
thx!
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#15 Stephen Williams

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Posted 30 August 2008 - 06:11 AM

Hi,
Anybody knows how can I install a capping shutter on a MK II?...I would like to use my MKII for animation and, as I can read here, I can't without a capping shutter...
thx!


Hi,

Please use your full real name, it's a requirement of this forum.

Depending on how involved you want to get, the easiest is just in front of the lens. Behind the lens is possible or even in the 'aperture slot' of aperture plate.

Stephen
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#16 Federico Vitali

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Posted 30 August 2008 - 01:11 PM

Sorry Stephen, just add my full name...;-)

Thank you for your reply.
I want to shoot frame by frame with a Revolution motor.
The problem is that I suppose I must do it myself...I've never seen this product on this camera. It seems to be really complex and difficult to build it. Have you a suggestion about a guy for working with this mechanism? Thank you again.

Federico
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#17 Stephen Williams

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Posted 30 August 2008 - 01:18 PM

Sorry Stephen, just add my full name...;-)

Thank you for your reply.
I want to shoot frame by frame with a Revolution motor.
The problem is that I suppose I must do it myself...I've never seen this product on this camera. It seems to be really complex and difficult to build it. Have you a suggestion about a guy for working with this mechanism? Thank you again.

Federico


Hi Frederico,

The simplest soloution would be a black card on a solonoid that caps the lens. The camera is probably light tight for 5-10 seconds but you may need to test. Leaving the eyepiece open could also be an issue.

If you speak to a rental house (where is the revoloution motor from) they probably have what you need.

Stephen
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#18 Federico Vitali

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Posted 30 August 2008 - 03:55 PM

thank's Stephen,
I'll ask the rental house. Hope they have a solution...If not, I'll try yours. ;-)

Federico
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