Twin Rig Test

[P3D brian whitehead <berger@xxxxxxxxxx>]

Hi All,
A friend of mine, Bernard Brown, has recently had to
change from his beloved Konica cameras (worn out) to a more modern
system. He has spent a great deal of time and effort in testing this
Pentax setup and hopes that his findings may be of benefit to anyone
thinking of setting up a similar rig.
Any further thoughts on the subject most welcome.

Brian Whitehead
Positive Image PS
Barry Wales

REPORT OF SUITABILITY OF PENTAX MZ50 TO BE TWINNED FOR OBTAINING FULL
FRAME STEREOSCOPIC IMAGES

                (1)     Availability - newly on market spring 1997.

               (2)      Cost - with Zoom 35-80mm lens #500 the pair.

(3)     Accessories necessary - two remote cable switches (1 metre) #52
pairs plus a custom made,tiny black box fitted on   paired cables,
designed and made by Pentax
U.K. Cost of adapting paired cables - #50.

(4)     Features - Zoom auto 35 - 80mm lens (there are other versions), 
auto wind, auto rewind, shutter or aperture Priority.  Hot shoe,, timer,
various other
"programs" and. auto exposure. Built in pop-up flash (up to 15ft - OK)
etc.

(5)     I am so accustomed to using "manual" on my old Konica's that Iam
initially setting up the twin rig on a bar for use in manual mode.  This
may be foregoing the selling feature of the camera, all singing and
dancing, but I know what I'm doing with manual - I'm in charge.  Perhaps
later I will look into the possibility of using other features that the
MZ50 offers.

6)     As we know, on choosing cameras for stereo, close synchronisation
is a must,  so, as before, I 
took advise from my mate Alan Griffin in Australia on testing for
shutter speed synchronisation as 
follows -Arrange a deal with your camera shop and have three 50MZ's to
play with.(You will need to have the paired remote leads fitted with
"black box" which would be made up first).



(7) Testing for synchronisation.  


 (a)    With the lenses removed from the cameras open up the backs and
witha small screw driver lightly press down the small switch in the
latch socket.
(This action will temporarily override the safety feature of' preventing
the shutter
firing with back open).


(b)     Plug in the "prepared" twinned cable releases with only one push
button switch fitted.  Have a well lit white card positioned at back of
testing
bench.  Place one camera with back opens facing the white cards then
place second camera, with front
facing front of first camera.

c)    Set the shutter speed (manual) on both cameras to 1/30th sec. 
With your eye as close 
to the open back of camera two as is comfortably use the switch on the
remote cable to fire 
both cameras.

(d)     If you see an uninterrupted white rectangle of light it means
that the cameras are in 
sync at that speed.  Raise the pairs of shutter speeds progressively
higher (together) until you 
notice cut-off of the rectangle.  This is the highest speed at which
these two cameras can be 
used in perfect synchronisation.

(e)     Take camera three and go through the same procedure as before
with cameras one 
and two.  The aim is to find the highest matched shutter speed.  These
are the ones you should 
purchase.


(f)           I have found that my best test gave me 1/180th of a second
with 1/250th sec giving 
good but not consistent results.  I have in the past, used higher speeds
for aircraft (prop jobs) 
and the pictures are very good except for the props being slightly out
of synchronisation, 
which, if only slightly out of synchronisation often adds to the realism
of the shot - thus 
avoiding the model aircraft look.

(g)        This will set the theorists going.  If its OK. on the
projected screen a certain amount of 
theory can be safely ignored.  I also mount each image individually with
comfortable viewing 
and spacial positioning (re window)p this is my basis for mounting.  I
do not believe that 
everything should be mounted at infinity and always at l.2 mm or some
such figures as an 
unbreakable rule.  As the "base" is approximately 6" I never have
anything nearer the camera 
than 10 ft.



I can safely set manually the distance of 25ft on the lens and at manual
aperture of P 5.6, my tests 
have shown that I have a sharp image from 10 ft to infinity. I also "toe
in" the cameras at 10 ft giving 
me a "sharp allover" full frame pair of images which are easy to mount
in glassless plastic mounts.



Conclusion

If I could find a pair of cameras that gave me the following features I
would be delighted:



1.      Auto wind on.

2.      Manual control of speed and aperture.

3.      Good zoom lens.

4.      Remote electrical release.



But I suppose with our stereo requirements we are a small minority and
manufacturers are fighting in the 
"flattie" market with more and more gimmicks (features modes, programmes
etc.). so I must be very 
thankful that the "goodies" can be adapted to my requirements.  All in
all would say that the Pentax 50 MZ 
will fit the bill nicely.

P.S. I forgot to mention that the cameras and lenses are so light that I
may get rid of my aching neck 
syndrome.



Bernard C. Brown FRPS,  APAGB, AWPF
Barry,  South Glamorgan , Wales
August 1997.


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