P3D Re: Instant Anaglyphs

[PK6811S@xxxxxxxxxxxxxx]

In recent postings I am hearing two objections to the claim for full-color
stereo anaglyphs.  First, that you can not make a full color photo with
a pair of red-andsomething color filters. and second that a single-lens
system is inherently not capable of making a stereo pair of full-depth
images.  Both of these objections are disprovable.  (I have pictures! :-)

The ideal pair of filters will pass the entire light spectrum and create
a full-color image.  Expose a frame through one filter, re-expose it
through the other filter to make a full-color image.  If one of the
filters chosen is red, passing light above a certain wavelength, then
the other should pass all light below that limit, the closest
approximation is a blue-green filter often referred to as cyan.

Images I have made with various combinations of red and blue-green lighting
gels demonstrate that full-color is possible.  You can see a difference
between using the filters and 'shooting clear', but the two are not
'more different' than the difference between brands of film.

Depth-of-field in a lens-produced image is related to aperture size,
smaller apertures give greater dof and larger ones give lesser dof.
Pinhole cameras have tremendous dof and overhead projectors with
large lenses have zero dof.  This principle applies as well to
sl3d as to normal sl2d photography.  Stopping down one of the filters,
say the red one, will create a red image with greater depth than
the overlapping b-g one.  Stopping them both down will give a matching
pair of deep images.

Two pinholes with underlying prisms is a variation of the sl3d system.
Pierce two holes in a sheet of dark card stock and hold them over
the face of your camera lens.  The lens fills the role of the two
prisms.  You will get two overlapping images each made from the
perspective of one of the holes.  Smaller holes give images
with greater dof without changing the stereo base.  (This arrangement
is not useful in practice - since the pinholes are not at the
aperture stop the images will be vignetted in opposite directions)

Other objections to sl3d systems are: stereo base limited by 
diameter of lens, and retinal rivalry (the red-and-white striped
ball is a great demonstration).

In practice, I have shot red flowers against green foliage with no
serious retinal rivalry - natural colors are not as limited as
artificial ones.  Faces, earth-tones, clouds, and sky do not present
problems.  Clothing, painted signs, and cars do.

I recently obtained a set of three 114mm F1 tv projection lenses at
a rummage sale.  At 114mm diameter they have great potential for sl3d
systems, since I may finally be able to obtain that magic 67mm base
not possible with my other camera lenses.  At F1 they can take much
faster exposures as well, I was pretty much limited to stills before.

Is it a toy?  Well... children have toys, adults have hobbies.  For
me it is a part-time hobby that is interesting, educational, occupies
my time, and puts me in contact with some good folks I would not
otherwise encounter.  If I ever make any money at it you all will
be the first to know!

Paul Kline
pk6811s@xxxxxxxxxxxxxx


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