|
|
|
|
|
|
Since many of those attempting to build and operate this device have
absolutely no prior experience with 3-D in any form, the instructions
will have to be both overly simplified AND overly complicated, for there
are important theories of stereoscopy that must be understood along the
way. A good analogy is a layperson building a liquid fueled space rocket
from printed instructions. It would of course be helpful if that layperson
learned a thing or two about rocket science along the way, but not so
much as to hinder the entire project.
If the rules are followed and comprehended, then the builder will be
rewarded with a 3-D movie unit capable of feature film quality 3-D movies.
The images produced can be razor sharp and better than any 3-D you have
ever seen before, even in theme parks.
The heart of this system, and the most costly to obtain, is a 2x anamorphic
lens. The lens must be of the type intended for both photography AND projection.
A theatrical projection lens alone will not work, for it usually cannot
focus closer than 20 or 30 feet. A photography/projection lens is required.
The lens used for my experiments was a Kowa 16-H 2x lens, which focuses
down to 5 feet. These lenses are very common used, and seldom cost more
than 200 dollars. I bought mine in great shape for 75 dollars from a cine
dealer.
|
|
|
|
|
The units final
form is determined by the camera it is built for. It is therefore recommended
that it be built around a common type of camera, in the case of 16mm,
a Bolex reflex or an Arri 16.
The camera I use is a Doiflex 16mm reflex camera, with a
25mm Cooke f1.5 lens. The device gobbles light, so try not to use anything
slower than 2.8, but 3.5 will work. You will not have a choice of focal
lengths to use once the unit is built, because the device works like human
stereo vision- one focal length, all the time, and no zooms. Besides,
the critical alignments of the mirrors would instantly change if the focal
length was varied by zooming or replacing the prime lens with another
type.
So, step one in this project is to have the anamorphic lens,
the camera, and the prime objective lens. For 16mm, you can't use wider
than 25mm with a 2x anamorphic. So the task is simple for the 16mm'ers:
you first need a 2x lens, a 25mm prime, and a REFLEX camera. Trying to
use a non-reflex camera would result in frustrating problems with lens
and mirror alignment. Also, zoom lenses can only be used in a fixed mode,
for zooming changes the optical characteristics of the mirrors.
|
|
|
|
|
|
It must record two parallaxed views, and then upon "playback"
it must deliver each view to the proper eye. So the device we envision
must record two distinct views of the same scene, and then upon projection
the left and right eyes must receive the image recorded from the left and
right "eyes" of the camera.
So the unit must
see two pictures as us humans do. But how do we see images in 3-D? Hold
a pencil at arms length. Look at the pencil, and then the wall beyond.
Now, slowly close one eye, then the other, back and forth. You will notice
that the pencil and your hand seems to move horizontally in relation to
the background. The reason is that there is a perspective shift between
your two eyes, spaced about 2.5 inches apart. This conflicting information
is what the brain uses to "solidify" the external world by perceiving
depth.
|
|
|
|
Look at the pencil again, but focus (converge) your eyes
on the pencil. Now alternate your eyes opening and closing again. You
will notice that the pencil remains fixed, but the wall beyond seems to
move from side to side. Now, repeat the experiment again, but this time
focus (converge) your eyes on the wall beyond, not the pencil. Alternate
your eyes opening and closing again, and now you will notice that the
wall is fixed, and the pencil is moving from side to side.
What is occurring here is that in the first instance your
eyes converged on the pencil, and in the second instant the convergence
was upon the wall beyond. That is all we will talk of convergence for
now, but know that it will come up again, in fact everywhere, for convergence
is as important to 3-D photography as focusing is to standard 2-D photography.
In fact, be aware that what makes a bad 3-D film is poor understanding
and disregard for the laws of Stereo, beginning with Convergence.
It should also
be noted that the anamorphic lens has nothing to do with the registration
of the 3-D images. The mirrors do that. The lens preserves the proper
1.33:1 aspect ratio. Without the lens, the device can produce excellent
vertical 3-D images, the screen being shaped like a doorframe. This is
an interesting challenge to the short film maker or artist, but totally
impractical for those wanting to make "full screen" 3-D features.
This is what all the other parts
are built around. The baseboard can be aluminum, steel, wood or even reinforced
plastic. Once the baseboard is fashioned, then the camera is mounted to
it, in such a way that it can be removed for servicing, but always returned
to the same critical position. The camera has its own "footprint"
so to speak.
Once the camera
is secure on the baseboard, the anamorphic lens to be used is mounted
in its yoke. Again the lens, like the camera, can be removed and returned
to its proper position. After the camera, baseboard and anamorphic are
secured and aligned, then the process of installing and calibrating the
mirrors is performed. When this is done, the unit is ready for filming,
and can be completely disassembled and rebuilt with great precision, in
the event that any part-camera, lens or mirror, needs to be cleaned or
repaired.
|
|
|
|
|
|
This part is left to the builder, on account of the different
projectors to be used and the fact that once the builder has built the
unit for photography, projector modification will be relatively simple.
Still others will electronically process the images in video form, and
use anaglyph or field sequential (shutter glasses) to present the images.
But by far the highest quality images are those shot on film and projected
with polarizing filters.
If you are ready to begin, then you need to
collect your 2x lens, and your camera with prime lens. If you are going
to use a video camera or a 8mm-16mm camera with a built in zoom, then
you need only to find the 2x lens. Remember! The anamorphic lens must
be able to focus down to 5-6 feet, unless it is a "fixed focus"
anamorphic intended for photography. Beware of theatrical anamorphics
that can't focus up close!
In the next article I will describe the fabrication of the
board as well as additional bits of stereo theory. If you are truly serious
about building and understanding this device, then you will, perhaps with
a small bit of trial and error to challenge you, possess a real 3-D movie
camera.
|
|
|
|
|
