Single lens 3D questions

[P3D Peter Davis <pdavis@xxxxxxxxxxxxxxxxxx>]

I recently acquired a Vivitar Q-dos lens, and have only tried one roll
of print film through it.  My next experiment is to shoot a roll of
slides, and view through a Sawyer's Bi-lens viewer with filters placed
over the lenses.  One positive comment I'll make is that this is by
far the easiest method of 3D photography I've ever tried.  You simply
use the SLR as you would normally, but switch on the Q-dos mode to get
anaglyph pictures.  You process the film normally, and the results can
even be viewed without glasses as tolerable "flatties."

However, I've noticed some distinct drawbacks to this system.  I
realize the Vivitar Q-dos is reputed to be a terrible implementation
of a great idea, but the problems I'm seeing seem to be inherent in
the technique.

   1)	Colors which are close to the red and cyan of the system's
	filters exhibit strong retinal rivalry.  They appear to
	jump out of the picture and flash.  This seems to be an
	unavoidable problem with this format, but perhaps I've
	overlooked something.  Obviously, avoiding subjects with
	those colors would help, but that's not always practical.

   2)	Since the system depends on shallow depth of field, the
	effect works best with a wide aperture, so much of the
	picture is out of focus.  Our eyes also have a limited
	depth of field, but we tend to automatically focus on
	whatever we're looking at, so it appears that everything
	is always in focus.

By the way, the Vivitar Q-dos uses a configuration like this:

		 /| |\
		( | | )
		 \| |/

The left and right portions are colored.  The center has a clear
vertical band, bounded by two black stripes.  I assume the clear band
was put there to simplify focussing and center-weighted metering, but
I can't think of a reason for the black stripes.  My understanding is
that the filters would be more effective if they actually abutted in
the center, with no separation.

Does anyone know how much work it would be to replace these filters?
I really like the switchability of the Q-dos, and that would be hard
to achieve with any other lens.

Thanks,

-pd


--------
Peter Davis		       "Education is not the		 617/873-4145
BBN Educational Technologies	filling of a pail, but	    FAX: 617/873-2455
70 Fawcett Street		the lighting of a fire."       pdavis@xxxxxxx
Cambridge, MA 02138			-- W. B. Yeats

	URL:  http://copernicus.bbn.com/people/PDavis/


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