Pulfrich Roses
by David Starkman & John Dennis

Reprinted from the July/August 1998 Issue of Stereo World

Pulfrich videos have had a mixed reception in recent years, with some very poor examples of the technique appearing on the market as tapes and others on the air as heavily promoted "3-D" broadcasts. Until now, one of the few encouraging and thoughtful Pulfrich applications was seen in an episode of Third Rock From the Sun several months ago.

With the release of A Walk Through the Roses of Reynolda Gardens, NSA member Dave Combs has added another video tape to the few that reveal the useful potential of the Pulfrich effect while avoiding the inherent limitations of the method. Where some TV productions and commercial videos have allowed random movements to completely ruin any coherent 3-D effect, Roses was recorded with great care to keep most camera movement in the proper horizontal direction at a constant speed. The result is often hard to distinguish from a video made with a 3-D camcorder or dual video camera rig.

By placing a neutral density filter over one eye, the Pulfrich effect occurs when the image seen by that eye reaches the brain a fraction of a second later than the one from the unfiltered eye. A subject or camera moving horizontally can produce, in effect, a series of sequential stereo pairs which, under ideally controlled conditions, mimic true stereoscopic photography. Except in computer animation, those controlled conditions can be nearly impossible to arrange when dealing with real life subjects. (See SW Vol 15 No. 6, pages 2 & 14.)

Dave Combs' Roses tape was made by moving a normal video camera past the rose bushes of Reynolda Gardens in Winston-Salem, NC, at about nine inches per second. This relatively slow speed made close-up stereo images of the passing roses work quite effectively, with only an occasional gust of wind blowing a branch in the wrong direction to create a brief pseudoscopic glitch in an otherwise well controlled production. With a running time of over 56 minutes, this tape provides ample opportunity to study the Pulfrich effect and its possible application to other subjects. Of course without the glasses, it works as a perfectly ordinary video--one that only a true rose lover would probably watch from beginning to end, but one that can beautifully demonstrate just what can be done with any camcorder and no extra expense beyond an old pair of sunglasses with one lens removed.

Roses is a more elaborate production of course, made using professional Steadicam® equipment and including music composed by Dave Combs and performed by Gary Prim, with two pairs of Pulfrich glasses provided. It is available to NSA members for $16.95 plus $3 shipping from:

Combs Music International
421 Cedar Trail
Winston-Salem, NC 27104
(800) 932-6627
e-mail:
Web site: www.combsmusic.com


Reprinted with permission from the National Stereoscopic Association.
Copyright © 1998 by National Stereoscopic Association, Inc.
PO Box 14804, Columbus, OH 43214
www.nsa-3d.org

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