P3D Realist system flawed?

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

It started as a joke but now it got serious... I will like to spend some
time replying to Boris' comments on the Realist system because I consider
the issue very important, especially for those who are about to make
choices for their own stereo photography.

Boris says that that the Realist system is significantly flawed because it
is non-ortho stereoscopic.  What Boris means is that the focal length
of the lenses in the Realist camera (which is 35 mm) does not match the
focal length of the Realist viewers (which is 44 mm)

How important is that mismatch?  Is it noticeable?  What effect does it
have?  

Boris says: "This results in a relatively narrow angle apparent
field of view, and a "stretched" spatial field."  
If you compare the views of a viewer with 35 mm (ortho) and the standard
Realist red button 44 mm, you will see a difference but I think this
difference is not very noticeable or very important.  There is also a
difference if you use the 44 mm viewer vs. other, cheaper, viewers that
have 50 mm focal length.

For most people and most subject maters, the effect ("flaw") is not
disturbing.  The proof is the success of the Realist system in the 50s.  If
the system was "seriously flawed", it would have not generated the response
it did.

Ordinary, 2D photography, is also non orthoscopic.  We view our 4" prints
from a distance longer than the ortho position.  To make things worse, 35
mm lenses are consider the standard FL in many cameras.  When we go to the
movies, most people sit well behind the ortho seat.  Same for watching TV. 
To stick with stereo, in stereo projection most people sit well behind the
ortho seats.  Some of the most popular seats are at the equivalent of 100
mm FL viewing.  If the 44 mm is disturbing, what can be said for the 100
mm?  I personally enjoy my projectionist spot at the 125 mm FL of my TDC. 
The judges that selected Boris' pictures for awards I bet were also sitting
well behind the ortho seats.

The orthoscopism that Boris advocates is based on the use of SLR cameras
with 50 mm lenses and a viewer with 50 mm fl. lenses.  Buy any attempt to 
pair SLR cameras, results in interocular separation that is wider than the
average 2.5".  For side-to-side SLRs this is 4" which is definitely not 
orthoscopic.

The other day I mentioned the work of this very successful photographer,
using 28 mm lenses separated at about 5".  Boris is also doing table top
photography which requires much smaller lens' separation.  He also creates
computer-generated images.  Others take hyperstereos.   All these interesting
forms of stereo photography are not orthoscopic.  Why is the matching of
focal lengths so important for Boris, while the matching of stereo bases 
or the content, is not?

>(As well as close-up views.  It doesn't help that the for
>use of a standard Realist, the recommendation appears to be to keep the
>subject more than five or six feet away.)

The recommendation (to keep the closest objects at or beyond 7 feet)
applies when the scene includes infinity.  The Realist camera can focus as
close as 2.5 feet.  If the furthest point is not further than 4 feet
then the closest object can be at 2.5 feet.  This recommendation aims in
keeping the maximum parallax under control for comfortable viewing.  It has
nothing to do with the Realist system specifically, besides the given
spacing of the Realist lenses.  It certainly has nothing to do with the
viewers.

>I am absolutely, positively, convinced that, had I started my stereographic
>work with a Realist, and followed all of the "instructions," I would not
>have had the success that I've had so far.  Not in small part because my
>own enthusiasm for the medium would have been diminished by the views that
>the Realist _system_ provides. 

How is your success measured?  Yes, I would agree that with the Realist
system you would not have the success you are having so far (as measured by
the reception of your stereo photography by the stereo photographic
circles) but I must also add that not many people could have started like
you did.  You are not an average person, picking up stereo as a hobby, like
most of us are.  You started as a photographer and you had the money and
equipment to proceed the way you did.

>Decent quality slide viewers
>for2x2x2 format are very affordable, and give a higher quality view
>than even the most costly standard Realist format viewers.

Excuse me?!  You mean the single-element plastic pin sharp viewer that you
are using is of higher quality than the Realist red button or Kodaslide II
viewers????

>This doesn't mean that I will never use a Realist.  If I get the money
>together, I may buy a Realist sometime.  

Yeah, right!!!  Sell one of your Nikon FILTERS and buy a Realist camera! 
:-) :-) :-)

Conclusion:  Yes, the Realist type viewers are longer in FL than the
Realist camera lenses.  No, for most people and most subjects this
mismatch is not disturbing, to the point of calling it a "serious flaw". 
For most people (but certainly not all), the Realist system is a better
way (read: cheaper, more convenient) to get started in good quality stereo.

Regards -- George Themelis


------------------------------