P3D How to take your own Pulfrich 3-D video

[Dave Combs <dcombs@xxxxxxxxxxxxxxxx>]

I have posted the following on my web site for those who would like to benefit from my experience in shooting my roses Pulfrich 3-D video. Any suggestions for improvement in my wording would be appreciated.

How To Take Your Own Pulfrich 3-D Video

While this roses video was taken using an expensive professional camera and a steadicamÆ operator and edited using state of the art non-linear digital editing, you can take your own 3-D video with your own camcorder by using the following guidelines and rules of thumb:

1. The camera must traverse the subject. Think of it as walking straight ahead while aiming the camera to your right at or close to 90 degrees. Or, while riding in a vehicle and aiming the camera straight out the passenger side window. Paning the camera, e.g. from a tripod, does not work. Also, shooting straight ahead does not work either.

2. Movement is required to achieve the depth perception. The moment you stop moving, the picture goes flat and the 3-D goes away. Unless you have video editing capabilities I recommend that you try to always start your movement before you start recording and then stop recording before you stop your movement. That way your resulting video will always have the 3-D effect.

3. Shoot the entire video moving in the same direction. If you change directions the viewers will have to flip their 3-D glasses around every time the direction of the video changes. This entire video was shot by aiming the cameral 90 degrees to the right while walking straight ahead, parallel to the subjects. The 3-D glasses have the dark lens over the right eye. However, the video could just as easily have been shot in the opposite direction in which case the 3-D glasses would then have had to have had the dark lens over the left eye. Just be consistent.

4. Regulate the speed at which you walk or ride so that the closest subjects to you on the video take approximately 2 seconds to pass across the screen. If you go much faster than this, things will fly across the screen too fast to see and appreciate them and probably will become annoying in a short while. If you are taking closeups of objects like I did in this video you have to go very slowly. I estimate that our camera was moving at about 9 inches a second. The farther back you are from the subjects the faster you can go. At about 4 mph the resulting 3-D perspective is approximately ortho (using 2.5 inches interoccular separation). Speeds faster than 4 mph result in hyper-stereo perspective and speeds less than 4 mph result in macro stereo perspective. In my video the speed I used translates into an apparent interoccular separation of .3 inches, about that of a large butterfly or a bumblebee, making for some giant rose blossoms.

5. As in regular stereo photography focus and depth of field are critical. With the video camera you need to use a shutter speed fast enough to freeze each video frame in focus. At very slow movement speeds normal shutter speeds whould be just fine. At higher movement speeds you will need to bump up the shutter speed accordingly. Also, the amount of light that you have available has a lot to do with how much latitude you will have in adjusting shutter speeds. Most of my video was shot in bright sunlight.

6. As in regular stereo photography you need to have subject matter that has multiple levels of depth. I always try to have at least three levels--close, medium, and far.

7. The subject matter needs to be relatively still. Slight movement such as when the breeze moves the rose blossoms is OK. However, larger movements will result in poor quality Pulfrich 3-D. The reason is that the brain is actually seeing two different frames of the video for a split second from two different vantage points due to the movement of the camera and if the subject has also moved between frames the resulting composite picture in the brain can be confusing.

8. Viewing the resulting video from further back from the TV screen seems to enhance the 3-D effect. Some people seem to want to move up closer to the screen at first, but the effect is better from further back. I am not sure why this is the case.

9. If the video was taken so that the images move from left to right on the TV screen (as if taken out of the passenger side, right side, of a vehicle) be sure and put the dark lens or filter over your right eye. If the video was taken so that the images move from roght to left on the TV screen (as if taken out of the driver side,left side, of a vehicle) be sure and put the dark lens over your left eye.

10. If you don't have a pair of the Pulfrich 3-D glasses, any pair of fairly dark sunglasses will do just fine. Watch the video with both eyes, but simply hold the sunglasses so that only one of the darkened lenses covers the proper eye (usually the right eye as in the case of the Roses video). If you wear glasses, be sure and put the 3-D glasses or sunglasses over the top of your regular glasses so you can still see the video clearly.


Dave Combs
Combs Music International
421 Cedar Trail
Winston-Salem, NC 27104 USA
E-mail: dave@xxxxxxxxxxxxxx
Internet Home Page: www.combsmusic.com
800-932-6627 (USA & Canada)
336-760-0037
336-760-3855 (fax)


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