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Trent Farm Photos an optical analysis
Dr Bruce Maccabee (US Navy Optical Physics)
(Page: 1/8)
(This paper was originally published in the proceedings of
the 1976 ufo conference of the center for ufo studies. This
version has been modified slightly in april 2000 for this
Publication. This is the first of two technical and historical papers on
The trent photo case that were presented to and published by
The center for ufo studies (cufos), which is located in Chicago,
Illinois. On the possibility that the McMinnville
photos show a distant unidentified object (UO)
During the Air Force funded investigation of UFO reports at the
University of Colorado in 1967-1968 (the "Condon Report"),
photoanalyst William Hartmann studied in detail photographic
and verbal evidence presented by two former residents of McMinnville,
Oregon, Paul and Evelyn Trent. He concluded, mainly on
the basis of a simplified photometric analysis, that "all
factors investigated, geometrical, psychological and physical,
appear to be consistent with the assertion that an extraordinary
flying object, silvery, metallic, disk shaped, tens of meters
in diameter and evidently artificial, flew within sight of two
witnesses." An important part of his analysis included
calculations of the expected brightness of the image of the bottom
of the Unidentified Object (UO) that appears in the first photo.
He pointed out that the elliptical image of the bottom
was brighter than expected if the object were close and therefore
a small model. The excessive image brightness led him to
conclude that the object was at a great distance (over a kilometer),
His conclusion was criticized by Philip J. Klass and Rober
Sheaffer who argued that veiling glare (caused by surface dirt
and imperfections in the lens which scatter light from bright
areas of the image into all other areas of the image) could have
increased the brightness of the image of the UO, making it appear
distant.
This investigation revisited and improved upon
Hartmann's method with the following modifications:
- the bottom of the UO in the first photo has been assumed to be
as intrinsically bright as possible without being a source of
light (i.e., assumed to be white)
- laboratory measurements
have been used to estimate the magnitudes of veiling glare added
to the various images of interest
- a film exposure curve
has been used to determine relative image illuminances, and
- a surface brightness ratio, determined by field measurements,
has been included.
The results of the new photometric analysis
suggest that the bottom of the UO is too bright for it to have
been a non-self-luminous white (paper) surface of a nearby object.
Hence it could have been distant.
Next Page (2/8)
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