P3D Re: Olympus XA cameras, New Mounting page is up

[Ralph Johnston/Linda Sherman <copley@xxxxxxxxxxxxxxx>]

This may be but my twin XA-2's have produced no unmatched exposures.  Also,
with the zone focus, it is easier to match that up on the XA-2's than with the
rangefinders on the XA.

There have been problems reported previously on this list about connecting the
release buttons of XA's together.  Connecting the shutters would get around
this problem.

I put up a page on "Mounting for Projection" which deals with adjusting RBT
mounts so the projectionist does not have to touch the knobs.

<http://www.ultranet.com/%7Ecopley/StereoNE/mounting.htm>http://www.ultrane
t.com/~copley/StereoNE/mounting.htm

There are numerous ACad drawings and an animated GIF drawing.

Here is the text:

I thought I knew how to mount until a few of my slides were projected for the
first time at a club meeting.  The
projectionist ripped them off the screen as being unviewable.  The problem is
that viewers are much more tolerant of
mismounting than projectors.  My camera (an RBT X-4B) has a 75mm base, so may
create stereo pairs with excessive
depth.  Stereo pairs taken by cha-cha shifting certainly can.  By my
measurements, a viewer can tolerate up to 2.5mm
divergence for far objects and up to 6mm of convergence for the nearest
object.  The projector can tolerate only 1mm
of either divergence or convergence.  Where did I get these numbers?  Measure
the distance from the left edge of the
window to a far object using digital calipers.  If the distance is 16.5mm on
the left image, then it shouldn't be greater
that 17.5mm on the right image.  This is 1mm of divergence.  Similarly, if the
distance is 9.3mm from the left edge to a
near object, then it shouldn't be less than 8.3mm on the right image. 

Each slide could be mounted this way without using a projector.  However,
projecting the mismounted slide can save
some time.  Adjust the horizontal knob until an object at mid-distance is
merged.  (Remove your polarized glasses) 
Then check the divergence of the far object by moving your hand back and forth
in front of the lenses.  The far object
should jump about 1.5" in the SAME direction as you hand is moving.
Similarly,
the near object should jump about
1.5" in the OPPOSITE direction.  Fine adjust the horizontal knob until this is
true and identify an object at mid distance
that does not jump.  Write down the object on a small sticky label and attach
to the center of the slide.  It might say
"Bob's nose", or "teacup", etc.  Do all the slides this way.  Later, on a
light
table, adjust the horizontal positions of
either or both film chips so that the distance from the edge to the selected
object is the same on both images.  Then
project them again and fine tune the mountings if necessary. 

If there is no middle object, then you have to revert to the 1mm rule and do a
measurement of the nearest and the
farthest objects. 





>
> ---------------------------------------------------------------------
>
> Date: Fri, 25 Dec 1998 11:44:15 +1100
> From: "David Stuckey" <dstuckey@xxxxxxxxxxx>
> To: <photo-3d@xxxxxxxxxxxxxxxxx>
> Subject: P3D Re: Olympus XA cameras
> Message-ID: <199812242158.IAA14672@xxxxxxxxxxxxxxxxxx>
>
> Refer to Duane Perry's question in PHOTO-3D digest 3129 about matching
> Olympus XA cameras.
>
> There are two issues here regarding the twinning of the XA or the XA2. 
> These cameras operate differently.Ý The XA is an aperture priority camera
> whilst the XA2 is a program camera, ie: it is programmed to go for the best
> D.O.F. by adjusting both aperture AND shutter speed.Ý This makes it much
> harder to match than the XA because you can get different apertures and
> shutter speeds with unmatched cameras.Ý 
>
>
> Duane Perry's question obviously refers to the XA2 as he is talking about
> different apertures and shutter speeds.Ý The answer is that adjusting the
> ASA setting won't fool the exposure meter of the XA2 because it controls
> BOTH functions, aperture and speed.Ý This is one of the reasons why I
> haven't yet attempted to twin the XA2.


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*      1) LINMAR PERSIANS (Solids, & Bicolors)
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