M2 Cinema Lens Adapter Setup Manual - page 7
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M2 Cinema Lens Adapter Manual
page
7
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Introduction to the M2 Cinema Lens Adapter
The M2 uses a device called a Cinescreen that is contained in the center of the M2 Housing. The
Cinescreen is a specially designed image screen mounted on a spindle that enables it to rotate at
extremely high speeds. The 35mm lens is attached to the front of the M2 housing, and focused to create
an image on the Cinescreen. A custom built achromatic lens is affixed to the front of your video camera
enabling the video camera to focus on the Cinescreen and record the 35mm image that is projected onto
the Cinescreen. When the M2 is turned on, the Cinescreen spins. This motion eliminates the appearance
of the Cinescreen grain, and provides a beautifully clear image.
How the M2 adapter works
Light from the scene passes through your 35mm lens, into the housing of the M2 adapter, where it
creates an image on the Cinescreen. The Achromatic Lens, a magnifying lens, enables your video
camera to focus only a few inches in front of the camera, on the small image on the Cinescreen, and to
record it. The 35mm lens and the Cinescreen together work very much like a
Camera Obscura
or like a
View Camera
. You can verify this by taking the M2 with a 35mm lens attached and looking into the back
(camera side) of it at the Cinescreen. You will see an inverted image.
Why the Cinescreen is necessary
It would seem that with the right combination of lenses and adapters, the light from a 35mm lens could be
focused directly onto the camera sensor. And this is possible. But it does not create the desired effect:
the 35mm look. Depth of focus is related to image size. If the final image is 1/3rd of an inch (about
16mm) then there will be a very deep focus. Getting an object in focus in the foreground against an out-
of-focus background might require that the background be 50 feet or more behind the foreground. This
deep focus is one characteristic of digital video. The goal is not just to shoot video through a 35mm lens,
but to get the look of 35mm film, including a more shallow focus. If the final image is closer to 35mm
(about 2/3rds of an inch), then there will be a shallower depth of focus. A background might only need to
be a few feet behind the foreground to be out-of-focus. The M2 adapter creates an image on the
Cinescreen that is close to 35mm in size, and displays a depth of focus similar to 35mm film.
Why the Cinescreen moves
There are two kinds of 35mm lens adapters for video cameras, those with static (unmoving) screens and
those with moving screens. The M2 uses a moving screen. When an image is created on film, the light
causes a chemical reaction resulting in small molecular structures called grain. The size and shape of
grain depends on the chemical process that occurs. The grain from one frame to another is always
different. With a static screen, imperfections in the surface of the screen can simulate the appearance of
grain. However, these shapes are unchanging from one frame to another and can be distracting.
Therefore, with a static screen, the challenge is to make the imperfections so small that they are not
noticeable – smaller than film grain. Our Cinescreen uses ground glass that has been manufactured so
that the imperfections are similar in size to film grain. When the Cinescreen is rotated by the motor inside
the M2 Housing, the grain pattern appears to be changing from one frame to another, just like film. The
result is a look that is similar to 35mm film.