[MF3D.FORUM:730] Re: I need a MF 3D Dr.

["Oleg Vorobyoff" <olegv@xxxxxxxxxxxxx>]

Your calculations agree with mine for 2.7mm on-film deviation.  Satisfactory
results with 65mm spacing eliminated the obvious suspects: vertical
misalignment, rotation, keystoning.  I presume you kept the backs of the cameras
in line when increasing the stereo base.  Also presume the bar did not bow when
both cameras were on it - this can cause rotational errors.

Maybe your eyes are simply intolerant of exaggerated stereo depth.  If so, you
might try setting far point to infinity in your stereo base calculations for all
shots.  You might also try reducing on-film deviation to, say, 2.0mm.  But
remember that if you overdo it you'll end up with flat slides.  Finally, you
might try exercising you eyes, say by freeviewing parallel and cross-eyed stereo
pairs, so they attain more flexibility.  But then again, you might end up losing
what seems to be the visual equivalent of perfect pitch.

As for mounting, it would be no surprise if on-film deviation did not come
exactly as calculated.  However, it should have come close to 2.7mm.  Did it?

Oleg Vorobyoff


Bill Glickman wrote:
>1.  I am using two M7's with perfectly matched 80mm lenses.  When I use each
>camera seperately and shoot the left and then a right shot with 65mm lens
>spacing it works perfect every time
>
>2.   When I use both cameras simultaneously on a slide bar with inter ocular
>spacing as per John B's formula, I can not get the chromes to completely
>fuse...
>
>3.  When mounting the chromes, I notice something odd.... when Paul Talbot
>was here, he showed me the use of the mount gauge.  Setting the nearest
>subject to the near line and furthest to the far line.... Both can NOT be
>satisfied at once with the John B spacing...
>
>4.  Greg Erker advised to take one camera for the left shot and then move it
>over and bring the other camera in for the right shot, maintaining 65mm
>interocular spacing.  I felt this was an excellent "process of elimination"
>test.   I did this, and voila it works.  That is why I wonder if the formula
>could be ill advised.  Here is some examples of the near and far in feet and
>the stereo base in inches I have been using...
>
>N   F     Base "
>10  26    6.5
>10  23    7.1
>10  20    8.0
>10  17    9.7
>10  14   14.0
>10  13   17.3
>
...