Standard's Adjustable Iris and Mat Controls

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Feel free to discuss any topic related to the Mitchell Camera. Both 35 mm and 16 mm models are welcomed here. Also consider posting topics of other major motion picture cameras that you feel are important to the development of the Mitchell Camera.

Update: You may have noticed that we have returned to just one category as opposed to dividing the forum into 7 different areas. Apparently, it was an unpopular change and returning to the old format will allow posters to find their submissions more easily.
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followthefocus1

Standard's Adjustable Iris and Mat Controls

Postby followthefocus1 » Tue Aug 19, 2014 1:18 pm

Hope it's OK to share some thoughts and passions about the Mitchell Standard's principle features WITHOUT seeming like a know it all. I am just amazed at how forward thinking John E. Leonard's designs were in 1917. We know that he revolutionized the rack over system compared to the existing Bell and Howell 2709's design. And also that George Mitchell purchased those patents to build what would become the Mitchell Standard.

But two other features were incorporated into all Mitchell Standards which I feel have been over looked when compared to the rack over system. They are the 4 Way Adjustable Mats and the adjustable Iris. The former was a feature which Mitchell kept all the way until the Mitchell BNCR (I believe). They allowed in camera effects to be easily accomplished by the twist of a knob. See white arrows showing the location of knob and one set of mat leaves. I find it humorous that the actual Leonard patent (I found on this web site's "Mitchell Patents" page) is tiled as: Adjustable Curtain for Cameras.

adjustable-iris-2.jpg

The other feature went away after the Standard gave way to the NC and BNC. It was the adjustable Iris. What a powerful feature to have when you might not have had enough flexibility with the f stop range of the lens you had to use. A super close up appears below.

adjustable iris 1.JPG

No wonder the Standard became the most sought after camera in Hollywood. All this in 1921 no less! Someday I hope to own a Standard but the prices are climbing every year, if you can even locate one. If someone can double check me on this following fact, but I have heard that they discontinued the adjustable iris before the actual end of the factory production of the Standard. Can't remember where I heard that tho.

Respectfully,
followthefocus1

justinwizard

Re: Standard's Adjustable Iris and Mat Controls

Postby justinwizard » Wed Aug 27, 2014 2:36 pm

Well hello. The adjustable iris was way cool. I agree it went away when they stopped production of the Standard but yes, Michell kept the 4 way adjustable mats. Must of been a spacing limitation with the "Falling Front" L base that precluded them from keeping it as a feature. Anybody else disagree with that?

More photos of the built in Iris below are from Rudie's web site: Calkovsky Camera and Lenses. In this particular case, he was selling a Mitchell Standard L base and nothing else. Because of that, it allows excellent view of the Iris!

It should also be noted that followthefocus1's pictures are also from the Calkovsky archive products page.

Be well,
Justiin
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sully in ny

Re: Standard's Adjustable Iris and Mat Controls

Postby sully in ny » Fri Sep 05, 2014 4:12 pm

i liked learning about theses features . it surprised me to see that u could buy a set of adjustable replacement mats over at cinemagear.com under their mitchell parts . they have so many spare gizmos u might be able to build a complete camera . i mean it . hey , i even uploaded a picture of 'em .

see ya,
sully
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mediaed
Posts: 42
Joined: Wed Apr 06, 2016 3:53 pm

Re: Standard's Adjustable Iris and Mat Controls

Postby mediaed » Sat Apr 30, 2016 4:13 pm

A quick correction here to your post, just wonder why not caught earlier. Mid-post, you state:

"The other feature went away after the Standard gave way to the NC and BNC. It was the adjustable Iris. What a powerful feature to have when you might not have had enough flexibility with the f stop range of the lens you had to use."

The iris feature was not an F stop replacement/supplement. Wrong place in the optical path. It was a masking feature. It could be maneuvered with the controls to anywhere in the frame and opened and closed as a matte.

Many early special effects were made on the set and in the camera. Those iris in and outs to black in silent movies where the face of the actor is ended in the shot or a point of interest is irised out from was done with this feature. (This is where the iris effect found in most video editing programs comes from.)

The rack over ability of the Mitchell made such effects easy to execute as the operator could see the exact effect setup through the taking lens before shooting it. Another mask feature that disappeared from the really early cameras with the changing of the times (and lack of demand) was a rotating disk that featured a keyhole or binocular among other shapes. The most used series of those shapes became the 4-way adjustable matte feature.

All big production Mitchells, up to and including the BNCR also had the capability--with the adjustable shutter-- to do fade-ins and fade-outs in-camera and, with careful backwinding, could do dissolves. Your second shot had better be good, for obvious reasons. Dissolves -- a feature welcomed in the 1920's where in-camera effects where the only way to accomplish these things were soon made more that obsolete with the development of the optical printer. Yet, that and the rack over is why so many Mitchells became special effects cameras in their latter years.

The best use of the shutter feature on set or location turned out to be in controlling strobe effects when shooting rotating or moving objects or in panning the camera. Ever see the odd western where the wagon wheels appear to be turning backwards? Bad shutter speed or the wagon changed speed during the shoot. In the "Cinematographer's Handbook" by ASC, there is a section on this that still is useful for digital cameras to which woefully few pay attention. ED.


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