140 THREE-DIMENSIONAL PHOTOGRAPHYviewer. His comment is most often “Why, that is not true! That
is not visible here. No such condition exists.”
The stereogram cannot be criticized except when correctly
viewed, for the subject of the criticism is not a photographic re-
production, but a synthetic image which is actually created within
the brain and which cannot be “seen” without the simultaneous
viewing of the two units. Moreover, as much as we like projection,
it is an error to undertake serious criticism of a stereogram as
viewed by projection. This should only be done while the stereo-
gram is viewed in an accurately orthostereo viewer.
Let us take as examples two very commonplace errors made by
the beginner, First we have a small lake, perhaps a mile across.
The near shore is nicely curved and presents the requisite trees
and shrubs. The whole is idyllic. But the sweep of water is the
thing which gives the scene its beauty. The poor beginner makes
his print and is dismayed to find his beautiful lake a mere smear a
quarter-inch wide across the print, with the trees at one side rising
abruptly to cut the composition in two.
The stereographer makes the same shot from the same position,
but he has no disappointment because his stereogram reproduces
the broad expanse of the water, giving it the weight it has in the
original. The water is not a quarter-inch strip, but a surface ex-
tending a mile back into the distance. The relative pictorial
values are just about upon the scale of one quarter-inch to a mile!
The next error is that typified by the profusion of growth in a
swamp. Most people think of a swamp as an expanse of soggy
grass and mud. On the contrary it is a place of luxurious growth,
tall plants and shrubs, gigantic trees, lush flowers, and mirror-like
pools. It is a subject which no amateur can resist, yet again the
planar print is a disappointment. The growth is so luxuriant that
the print presents a confused tangle of detail, all more or less in a
monotone of gray. One can point out the various features, but the
spirit of the swamp is missing, and the print is simply another
failure.
In the stereogram, this detail is resolved into its original three
dimensions. We can peep through the tall leaves of a lily to see
the sparkle of the swampland pool. The rising columns of the
trees with their patterns of cast shadows lend emphasis instead of
confusion. We look deeper and deeper into the depths of this un-