[photo-3d] Re: Wide-angle Stereoscopy and the LEEP 2/2

[abram.klooswyk@xxxxxx]

In December 2000 there was a P3D thread on the LEEP.

The news about the LEEP system (Large Expanse - Extra 
Perspective) was spread by Paul Wing in 1981, he wrote the 
article in Stereo World (recently referred to in P3D), it was 
in his column "Equipment Notes": "How about the LEEP system", 
Stereo World Jul/Aug 1981 vol 8 Nr 3 pages 20-21.

I wrote on the news also in Jul/Aug 1981 (without having seen the 
prototype) in the Dutch 3-D Bulletin Nr 57, and again in the 
Jul/Aug 1982 3-D Bulletin Nr 63. First a price of $200 had been 
mentioned for a basic LEEP system (camera and viewer). 
I commented that I had doubts on possible quality for that price, 
as a single 35 mm lens for a 6 x 7 camera (Pentax or Mamiya) 
costed a multiple of that amount.

In an article in "Design News" Nr 21, of Sept 21, 1981 by 
"East Cost Editor" David J. Bak: "Transparency 'corrects' 
distortion, color fringing" was explained how the LEEP system 
was supposed to correct lens errors.

"A wide angle photo-viewing system will impart distortion-free 
color imaging with minimal fringing." "... the LEEP method 
(...) a predetermined amount of positive distortion and 
lateral chromatism. Transparencies display barrel-shaped 
images and pronounced color fringing (...). When seen through 
the magnifying viewer lenses, images are corrected in that 
straight lines are straightened, and object appear as the same 
size as at the original vantage point of the camera. The 
system not only corrects distortions, but the color fringing 
on the transparency substantially neutralizes the lateral 
chromatism of the magnifier lenses."

A figure shows color fringing from a point source of white 
light by a "simple camera lens" on film, and a symmetrically 
placed  "simple viewer lens" which unites the spectrum again 
to a white line.

There was more about this in the description of the US patent 
4406532, issued Sept. 27, 1983: "Wide angle color photography 
method and system", inventor Howlett, Eric M. 
(Today the full patent description is on-line, ref. see below, 
 fig.2 illustrates the "Neutralizing of Lateral Chromatism").
In short, it is proposed to correct camera lens color dispersion 
by opposite viewer lens color dispersion.

Of course anamorphotic lenses are used in systems like Imax, 
but only for geometrical transformations, not for handling 
color dispersion. So at first the LEEP system seems a too 
optimistic scheme, resembling trying to correct an out-of-
focus transparency by de-focusing the projector lens... 
This seems in conflict with experience and laws of entropy. 
(I'm working on my General Unified Theory of Garbage, which 
will cover entropy, Bermuda triangle events, Murphy's law, 
chaos, American President Elections, the second law of 
thermodynamics and other strange phenomena). 

Stereoprojection of slides is to some extent optically 
symmetric to stereophotography, but stereoscope viewing is 
not. In viewing, the lens makes a virtual image at the same 
side of the lens as where the transparency (or photograph) is. 
You cannot easily use a camera lens for viewing.

However, the patent description was accepted by the US Patent 
Office, so there must be some truth in it, and indeed the LEEP 
pictures seem to support the claims. If the claims of the 
patent description are right, the LEEP viewer can only be used 
to view pictures from the LEEP camera. (So I wonder if Don 
Lopp has done that, or tried it with other pictures?)

>From 1982 I was one of the sponsors of the LEEP project, in 
fact camera serial #32 would become mine (but never was :-( ).  
I wrote to Eric Howlett about van Albada's efforts, and he 
wrote back that he indeed had filed his patent application 
with the van Albada paper as main reference (it is indeed in 
the patent description).

The project went wrong as we know. There were some irregular 
spaced newsletters from Howlett, who used the firm and brand 
names LEEP, Stereovision, LEEPMA and Pop-Optix Labs in the 
mailings. (One of the mailings included the sheet recently 
uploaded to the files section by Rod Sage, it is in my LEEP 
file, date Feb 1982. The lenses shown were from the production 
series. The text gives pre-production camera details, which 
slightly differ from the actually used specifications which 
are in Werner Weiser's book "Stereo Cameras since 1930",
see reference in posting 04 Feb 2001). 

In 1989 Howlett wrote: "In the middle of 1985 we actually 
shipped three LEEP systems (...)". A foot note added that one 
of them had "conked out". 
This was not very encouraging, 8 years after the first public 
LEEP announcements. Apparently financial and personal problems 
were too great.

In the mean time I had seen Paul Wing's LEEP pictures (and his 
camera) on several occasions, and I still hoped that the 
production number would reach #32, but eventually Paul told me 
confidentially that he didn't believe any more LEEP systems 
would ever be produced, which till today seems right. A sad 
outcome, but I would sponsor a new wide-angle stereosystem 
again, if there was some change to buy one.

Abram Klooswyk
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Below a summary of LEEP web references.
Patent text:
http://www.delphion.com/details?&pn=US04406532__&s_all=1
Patent figures:
http://www.delphion.com/cgi-bin/viewpat.cmd/US04406532__
LEEP "site": 
http://world.std.com/~leep/cat003/arv-1.htm
Pictures of LEEP camera and viewer, on the
Stereo New England / PHSNE site:
http://www.phsne.org/stereocameras/35mm-rollfilm/leep.jpg
http://www.phsne.org/stereocameras/35mm-rollfilm/leep_viewer.jpg
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