A Brief History of the McMinnville Photos (cont.)
The initial analysis was carried out by a photographer (Bill
Powell) who worked for the McMinnville Telephone-Register (now
the News Register). Hartmann confirmed the original analysis
and went on to conclude that the object was asymmetric and that
it was probably not rotating about a (nearly) vertical axis (i.e.,
was not thrown into the air). Hartmann pointed out that
the possibility for a simple hoax existed since the photos show
the UO as appearing to be "underneath" two nearby power
wires. However, he carried out a simplified photometric
analysis which led him to conclude that the object was distant
and that "the simplest, most direct interpretation of the
photographs confirms precisely what the witnesses said they saw."
A modified version of Hartmann's analysis will be presented
in the next section to illustrate the use of photometry. In
1974 Philip Klass (2) published an analysis of the verbal evidence
by himself and of the photographic evidence by Robert Sheaffer
(2,3). They found a puzzling inconsistency between the
photos and the verbal description: the photos show clear shadows
on the east wall of the nearby garage, which implies that the
pictures were taken in the morning, while the witnesses claimed
that the pictures were taken in the evening. Sheaffer argued,
on the basis of measurements of the width of the shadow
of the eave rafter at the corner of the garage, that there was
a considerable time lag between photos rather than "less
than 30 seconds" as claimed (see Figure 3).
most important "discovery" was that dirt on the camera
lens, or a poor quality lens, could have caused light from the
bright sky surrounding the image of the UO to "spill over"
onto the image of the UO, thus making the UO image excessively
bright. In Hartmann's analysis the excessive brightness
was attributed to the effect of the atmosphere on the apparent
brightness of an object if it were distant. By attributing the
excess brightness to a camera defect, Sheaffer was able to argue
(qualitatively) that the distance calculation was in error and
that "in reality" the object was close to the camera.
He was, thus, able to remove the main inconsistency with
the simple hoax hypothesis: the object, a model UFO, was hanging
from wires that were less than twenty feet from the camera.
In late 1973, unaware of the work of Sheaffer and Klass, I decided
to undertake an investigation of the McMinnville case because
(a) the pictures are so clear the object is either a hoax device
or an unusual object (no misinterpretation seems possible; e.g.,
it's not a plane at an odd angle), and (b) Hartmann had devoted
considerable effort and analytical research to the photos and
had concluded on the basis of this physical evidence that the
object was distant (not a hoax). Considering the general tone
of the Condon Report (skeptical), I felt that Hartmann must have
been quite confident to publish the conclusion he drew from his
analysis. He could have decided to do no photometric study and
then he would have been "safe" in saying that the case
provided "no probative evidence" and that, furthermore,
it was probably a hoax. Or, he could have reported the
photometric study with such disclaimers as "the photos are
so poor (scratched, worn, etc.) that the photometric study is
probably in error by a considerable amount." (NOTE: Dr.
Condon wrote in the executive summary chapter that photoanalyst
Everitt Merritt, who was not a part of the Colorado University
UFO research project, had already "thrown out" the
photos as being too fuzzy for worthwhile photogrammetric analysis.
But photogrammetric analysis, which makes use of angular
separations of images, is different from photometric analysis,
which makes use of relative image brightnesses. I am certain
that Condon knew the difference between photometric and photogrammetric
analysis. It appears that he tried to "cover up"
the success of one [photometric] with the "failure"
of the other [photogrammetric] by not mentioning Hartmann's
analysis in the executive summary of the research.) Dr.
Hartmann did point out that his analysis might only be correct
to within a factor of four, but, even with an error bar this
large, several hundred meters was the closest distance compatible
with his analysis.
Since Hartmann had essentially endorsed the photos as probably
genuine, I decided to try to either confirm or refute his
result in a study of my own. Since I was somewhat skeptical
myself, I fully expected to be able to show that either the atmospheric
theory he used or the photometric measurements were wrong (or
incorrectly applied). After a several year study, I have concluded
that the general form of Hartmann's analysis is valid. However,
I have found that he ignored or was unaware of several "details"
of the necessary photographic analysis which will be outlined
in the following section. I was not able to confirm the
specific numbers which he gave as relative brightnesses of various
images on the photos. At least part (perhaps a major part)
of this discrepancy is due to a difference in measurement technique:
Hartmann measured transmission values of small portions
of the images of interest and then divided by the transmission
"somewhere" along the horizon; he thus did not have
good estimates of average brightnesses of the images. I
used a scanning densitometer with a very small aperture and averaged
over many scans across an image of interest. However, despite
the (not large) difference in the relative brightnesses obtained
in the two independent investigations, the conclusions have turned
out to be essentially the same, as will be seen.