P3D Re: 3D Movies

[boris@xxxxxxxxxxxx (Boris Starosta)]

Hello All:

Have been away for a while, so this replies to something way back in digest
2662:

>Date: Fri, 3 Apr 1998 03:24:58 -0500
>From: Marvin Jones <Campfire@xxxxxxxxxxxxxx>
>To: "INTERNET:photo-3d@xxxxxxxxxxxxxxxxx" <photo-3d@xxxxxxxxxxxxxxxxx>
>Subject: P3D Re: 3D Movies
>Message-ID: <199804030325_MC2-38DA-679@xxxxxxxxxxxxxx>
>
>Message text written by INTERNET:photo-3d@xxxxxxxxxxxxxxxxx
>>I was thinking about (planning to) shooting a 3D movie and I was
>wondering if I should use a 60 to 70 mm stereo base all the time or
>use the 1 in 30 rule and readjust the stereo base for each shot.  Does
>any body have knowledge or experience in this area?  If you do, I
>would be very greatful.<
>
>My own approach would be to adjust the base within reason for each shot,
>because I would want to try and keep the main focus of attention near the
>stereo window. I think a lot of the "eye strain" that some people associate
>with 3D movies comes from sudden and frequent shifts in the apparent
>position of the focus of attention, especially when the "apparnet" focus
>(where the subject APPEARS to be in space) is radically different than the
>"actual" focus (the screen plane).
>

I've never shot 3D movies, so I'm just going to give my totally uneducated
opinion, here.

The original question regards the use of variable baselines (inter-ocular
separation of cameras/lenses).  This is something that would control the
perceived scale of space within the shot.  A large baseline (say 500mm)
would make the scale of the observed scene appear smaller than a "normal"
baseline of 70mm.

The answer given by Marvin Jones addresses the location of the stereo
window.  He suggests that the photographer keep the focal point of the shot
at the same location (depth) as the window (and keep that on the actual
silver screen).  But although the baseline will affect the location of the
stereo window to some extent, it is not the controlling factor.  Placement
of the stereo window is controlled by convergence of the cameras.  (John
Bercovitz has told me that stereo window control through camera convergence
is the accepted norm in 3D cine production).  So, even if you shot the
entire production with a baseline of 70mm, you would still want to adjust
your convergence to place the window at the same depth as the focal point
of the shot.

Certainly modern cinema relies on very dramatic jumps in scale between
shots.  You'll have extra close-ups of actors faces followed by a grand
wide angle establishing shot of mountain range, etc.  I you really WANT to
show those mountains with three dimensional depth, of course you'll have to
use a much larger baseline than was used on the actor close-ups.  My
preference would be to stick to a single baseline (But I've hardly seen any
3D film at all, and none since I started my involvement in 3D photography -
so what do I know?).

Respectfully submitted,




Boris Starosta

usa 804 979 3930

boris@xxxxxxxxxxxx
http://www.starosta.com
http://www.starosta.com/3dshowcase



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