The details of this sighting obviously show a striking resemblance to some of those in the Mantell case (p. 33), in which the UFO and the sun had the same bearing from the pursuing plane as in the Salt Lake City incident. With the information now available, there can be little doubt that Mantell was actually chasing a Skyhook balloon. But in 1948 when so many of the relevant facts were not known, the sundog theory was a reasonable solution and may still be the correct one. _Bright Spots on Films_ A bright blur, a ring of light, or a circular image something like the typical disk-shaped flying saucer sometimes appears on a film, much to the surprise of the photographer, who had not noticed any such object when he took the picture. These UFOs are usually caused by reflections from unnoticed drops of moisture in the air or by defects in the camera itself (see Figure 17). If the source of the image is something peculiar, it may pose a real problem (see Plates VIIIa and b). [Illustration: _Figure 17._ Distorted images produced on film by lens defects. A, True image; B, image produced by poor lens, not well figured; C, by astigmatism; D, coma; E, off-axis beam; F, off-axis beam and coma.] On July 24, 1957, an American tourist in Norway snapped a picture of a group of houses on a cliff above the seacoast, and was amazed to find some time later that the print showed a large white, doughnut-shaped object hovering in the sky above the coast. Puzzled by this apparent evidence of a saucer that had been visible to the camera but not to her, she submitted the facts to ATIC investigators. Thorough study of the negative, the camera, possible sources of reflection in the landscape at the time the photograph was taken, all failed to account for the mysterious intruder. Obviously not a cloud, the image closely resembled a smoke ring, but the photographer had not been smoking and there were no sources of smoke in the neighborhood. The experts were baffled until one of them thought of a new possibility and again questioned the witness: had she by any chance been wearing a ring when she took the picture? She had--a sparkling diamond. If the angle of the sun, the direction she was facing, and the position of her ring finger in relation to the camera lens and to the sun had been exactly right, the annular image would have been reflected into the lens at the instant she snapped the picture. The resulting bright ring would look exactly like the UFO that appeared on the negative[XII-1] (see Plate VIIb).