P3D Mounting stereo prints

[dale.walsh@xxxxxxxxxxxxxxx]

	Concerning questions asked about mounting stereo prints, I havve taken the=
 liberty of sending a few quotes from an excellent resource for 3D photogra=
phy which is available from the authors below.  If anyone is interested, I =
could get you the address.  Hope this helps.

	Dale Walsh


A STEREO/PHOTO GLOSSARY

  =20

   by: Craig Daniels and Dale Hammerschmidt



 Scopeability:  A jargon term used in reference to a view's over-all ease o=
f being  viewed.=20

Standard separation of homologous points, suitable deviation, absence  of r=
otation, a well placed

window, balanced printing, accurate image  alignment/masking/trimming --- a=
ll of these

contribute to a good view. This is  sometimes spelled scopability,  but to =
describe  the difference

as a point of  controversy would be overstatement.


*  Interpupillary distance (IPD):  The distance between the pupils of the e=
yes when vision is at

infinity.  IPDs range from 55 to 70 millimeters, but the average is usually=
 taken to be

somewhere between 63.5 and 65 mm (2-1/2 inches).


  Interocular distance:  The separation between optical centers of a viewer=
 (which may be

adjustable). (From L. oculis, eye; an ocular lens is one through which the =
eye views, as opposed

to an objective lens. So the interocular distance is the distance between t=
he optical axes of the

eyes themselves, or of the ocular lenses of the viewer =5Bwhich should be t=
he same=5D). In

stereography, the term is usually used to refer to the distance between the=
 axes of the ocular

lenses, which may not be quite the same as the distance between the axes of=
 the eyes (for reasons

of collimation =5Bq.v.=5D). =7BIt is a common error to assume that the inte=
rocular distance should agree

with the interpupillary distance of the observer. It should be equal to or =
slightly greater than the

maximum separation of homologous  points of the view (in the case of a simp=
le viewer) or such

points of the image formed by the objective lenses (stereoscopic optical vi=
ewing system).  See

=22collimation.=22=7D


Collimation: When the distance between the optical centers of a stereoscope=
 and the separation

of the image pair placed in it are equal, and when the images (or view) are=
 (is) placed at the full

focal length, the lenses of the stereoscope act agreeable as =22collimators=
=22 for the =22homologous=22

points of the image pair. This means that the interpupillary distance of an=
y user's eyes is

automatically accommodated without adjustment. It also means that one's eye=
s need not be level

with the view (a great convenience in viewing).  Accordingly, gravity-level=
ed eyewear has been

proposed for viewing side-by-side pairs presented ion a fixed screen at clo=
se range.


=20

*  Interpupillary distance (IPD):  The distance between the pupils of the e=
yes when vision is at

infinity.  IPDs range from 55 to 70 millimeters, but the average is usually=
 taken to be

somewhere between 63.5 and 65 mm (2-1/2 inches).

=20


A special case worth mentioning is the use of windows with arched tops. Bec=
ause the arches are

in part vertical, they give distance information. Therefore, if one uses th=
e upper edge to align

the homologous points in a print, there is a great danger of error; homolog=
ous points should be

the same distance below the top edge (of a curved top) only in the object i=
s meant to be in the

plane of the =22window.=22 This may be seen in the illustration below. The =
caneweave- patterned

blob is in the plane of the =22window,=22 and is identically positioned in =
each frame. The speckled

blob is behind the =22window,=22 and is slightly further down from the top =
edge in the right-hand

=22chip.=22 But it's the same distance up from the bottom of the image in e=
ach =22chip.=22 It is best for

arched tops to make all measurements from the bottom, and with great care.

=20

	Homologous distance:  The distance between two =22homologous points=22 (me=
aning the same ---

except for being the left and right versions) in a stereo view.  The maximu=
m separation of such

points in a view's distant subject matter are often said to be =22the separ=
ation=22 of the view, and

held to some standard.  The optical centers of the lenses of a stereoscope =
(or free hand lorgnette)

are separated by this distance or more.






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