94 THREE-DIMENSIONAL PHOTOGRAPHYera and vice versa. The reason is that the sense of balance changes
as the head is moved, and when the balance of looking upward
is present, the appearance is rendered even more realistic.
But to get back to the level camera. As a rule the camera should
be level from side-to-side, that is, one lens should not be higher
than another. The reason is perfectly simple. The stereo picture
cannot be twisted and corrected as could a similar planar photo-
graph, because the common central axis must be retained if un-
comfortable vision is not to be encountered, If the camera is
tilted, the pictures are mounted with the scene at a slant. If this is
done, the stereogram is visually acceptable, but hardly satisfactory
esthetically.
As far as the rule is concerned it might be stated thus, “If you
want your pictures to be straight, keep the camera level from side-
to-side.” As a matter of fact, the camera can be side tilted to pro-
duce some highly fantastic effects, provided the conditions are
right.
Another factor is that of the tripod. Color film is still relatively
slow, and there are very few people who can make a needle sharp
film with a hand held camera operated at a longer exposure than
1/50. Most of you will ignore the advice, of course, but those of
you readers who do make use of a tripod will be more than repaid
by the great improvement in the quality of most of your shots, and
you will be far less handicapped in losing those subjects which
require 1/10 second or more exposure.
The stereogram should be sharp throughout if the full realism
is to be retained. However this “rule” should not be given too
much consideration when the loss of a picture is involved. If you
can obtain a satisfactory stereogram which includes some blur,
and cannot make an exposure at all with the aperture necessary
for all-over sharpness, by all means do the best you can. A stereo-
gram of an interesting subject, even if subject to some technical
criticism, is far better than no stereogram at all.
The “rule” actually originated in the days when extreme soft
focus was a fashion and every photograph had a series of abruptly
changing planes. This was said to imitate the effect of human
vision, although why such an absurd statement should have been
made by men and women whose own eyes constantly wander from
point to point, cannot be understood. Many stereographers went