Source:http://brumac.8k.com/trent1_1.html

The Trent Farm Photos 

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).  However, Sheaffer's 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. 

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