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Contrairement à une idée reçue il existe de nombreuses photographies d'ovnis supposés. Bien sûr le problème ne réside pas tant dans les détails de la photographie et de son négatif que dans le photographe et l'équipement utilisé. C'est pour cette raison que l'on doit faire attention à pleinement documenter des détails apparemment sans importance concernant la personne prenant la photographie, la situation sociale qui entoure la(les) photographie(s), les données de l'appareil photo-objectif-pellicule, les activités de développement épreuve-agrandissement et la manière dont la photographie est venue à l'attention de l'enquêteur. Une telle image photographique étant aussi crédible que le photographe qui l'a prise, on doit exercer une "juste diligence" dans chacun de ces domaines. Nombre de vieilles photographies d'ovnis restent des éléments inutilisable de l'énigme ovni parce que l'enquêteur n'a pas ou n'a pas pu obtenir toute l'information contextuelle pertinente. Comme cela va être rendu clair, l'auteur a tenté de considérer tous les facteurs ci-dessus. Cependant, les contraintes de concision de cet article imposent certaines limites practiques quant au niveau de détail avec lequel ces faits peuvent être documentés.
Le reste de ce rapport couvrira les sujets suivants :
L'auteur a reçu une bande de négatif couleur de 2 images. L'image de numéro le plus élevé montre un petit enfant se tenant devant une cheminée dans une maison. L'image de numéro le moins élevé montre une montagne dont le sommet était pratiquement centré dans l'image. Le détail de l'arrière-plan était net, indiquant que soit vitesse d'obturation assez élevée a été utilisée, soit que l'appareil photo a été stabilisé, ou les 2. La figure 1 est un agrandissement de la totalité du négatif sous forme d'épreuve positive. Un objet net à l'apparence de disque est visible en haut à droite du sommet de la montagne. L'extrêmité de la montagne est située près du centre géométrique de l'image 35 mm. Ceci tend à soutenir l'affirmation faite par la photographe qu'elle voulait photographier les montagnes et n'a jamais vu l'objet aérien. La présence d'un nuage directement illuminé par la lumière du soleil à travers un air extrêmement clair fournit une limite supérieure d'exposition utile pour les mesures ultérieures de densitométrie. Des ombres vues dans un stand d'arbres à l'avant-plan gauche fournit une extrémité inférieure de l'exposition. Ainsi, un maximum de 12 500 pieds-L est supposé pour la luminance du nuage et approximativement 1 pied-L pour la zone ombragée. La clarté atmosphérique rend presque impossible de juger la distance séparant l'appareil photo et l'objet au moyen du calcul d'un coéfficient d'extinction.
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Le négatif mesurait 36 x 24 mm. Un agrandissement photographique de l'image du disque a permis des mesures linéaires. Son axe majeur sur ce tirage était de 5,70 cm alors que son axe mineur était de 1,60 cm pour un ratio largeur/hauteur de 3,56. La largeur du "dôme" protruding from the upper surface was 1.3 cm and its height about 0.7 cm (ratio of 1.86). Finally, the dome to disc width ratio was 4.38 and the dome to disc height ratio was 2.29. While these ratios are a function of the viewing aspect angle, they may, in general, be compared with corresponding values given elsewhere (Haines, 1978, 1979) of similarly shaped aerial objects of unknown origin that have been reported over the years. This previous work shows that the present photographic image of a disc is not uncommon; there is a larger context of purported UFO drawings into which this object fits.
The hyperfocal distance is the nearest distance from an object being photographed to the camera at which the object is in sharp focus when the lens is focused on infinity. Since the mountain is in sharp focus and the photographer said that she took great care to manually focus the camera it is possible to determine the hyperfocal distance by also knowing the focal length of the lens and its aperture (Neblette, 1965). For a 50 mm focal length lens and f-11 aperture the hyperfocal distance is 15 feet. Corresponding distances for f-8 and f-16 apertures are 20 and 10 feet, respectively. Thus, the airborne object in question must have been farther than ten feet (and probably farther than 20 feet) from the camera since it also was in sharp focus.
The actual camera settings used can only be inferred. A film with an ASA 100 exposure index (as this was) and a lens with the optical quality of this one would have very likely automatically pre-set a shutter speed of 1/125th second at an aperture of f-11 for the ambient scene luminance which was present.
Finally, the negative was in very good condition and did not have any visible scratches, major blemishes, or other defects. An invisible vertical scratch was noted in one of the dye layers as will be described later, however, this scratch was well away from the disc image.
The camera was a Mamiya, model 528AL, single lens reflex (SLR) type with permanently attached Mamiya/Sekor 48 mm lens with 1:2.8 aperture. The serial number on the lens was M197535. The camera is of the automatic exposure type meaning that all one needs to do to take a photograph is insert the film, pre-set the correct ASA number for the film used on the camera, aim and manually focus the lens for best focus, and press the shutter release. Both shutter speed and aperture adjust automatically for "best" exposure. The shutter actuation lever is of the standard top-mounted type which requires a downward finger depression. Once the shutter has opened and closed another exposure cannot be taken without first advancing the film to the next frame. The author borrowed this camera and took a series of photographs with it under closely similar sun angle, sky brightness, and other conditions to check on possible lens and/or shutter related image artifacts. None were found. The lens was coated with the standard anti-scattering material. No scratches or other flaws could be seen in the lens elements or surface coatings.
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The film used was Kodak Safety Film 5035, 35 mm, commonly known as Kodacolor II. Its ASA rating is 100. The photograph in question was located at frame 11. The so-called "characteristic curve i.e., exposure vs. optical density), modulation transfer function, and spectral sensitivity for this film are presented in Figure 2(a), (b), and (c), respectively (Eastman Kodak Co. Manual, 1980).
The concept of "graininess" and "granularity" of photographic film is important here. Graininess is defined as the subjective sensation one gets when viewing an enlargement of a photograph of a random pattern of variations in texture, color, or both in regions of homogeneous luminance and color exposure. Granularity is the result of an objective measurement of the film using an instrument known as a densitometer which measures the local density variations that give rise to the sensation of graininess (Kodak Publications F-20, 1973). Most silver halide crystals that make up photographic film are dispersed in a gelatin and coated in thin layers on a supporting (paper, etc.) base. Importantly, these crystals vary in size, shape, and sensitivity to light energy. In general, they are also randomly distributed. As the Kodak manual states, "Within an area of uniform exposure, some of the crystals will be made developable by exposure; others will not. The location of the developable crystals is random" (Kodak Publication F-20, 1973, p. 3; italics mine).
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One result of this random distribution of light-sensitive crystals (grains) is that patterns can be produced which have nothing to do with the object that was originally photographed. If such a pattern is perceived as having a recognized shape, it is possible to conclude that the shape represents an object somehow related to the primary object when, in fact, there is no functional correlation with the object.
The diameter of the film's crystals is also important. The Kodak film manual indicates that a typical crystal diameter ranges from 0.2 to 2.0 micrometers. At a normal viewing distance of 25 to 35 cm the human eye can just discriminate a crystal (grain) on the order of 0.05 mm diameter. Normally the eye does not perceive the granular structure at low magnifications. The finer the mean diameter of the crystals the higher the magnification can be before graininess is noticed. It is the random nature of the exposed crystals, each possessing a different spectral reflectivity in white light, which is a necessary condition for the appearance of graininess to occur. Also, the mean diameter of film crystals becomes a significant factor when deciding on a diameter for a scanning digitizer's entrance aperture. A six micron diameter aperture was used here which was approximately 1/2 mean crystal diameter of the present film.
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The roll of exposed Kodak film was developed commercially. According to the photographer, a normal processing delay occurred (approximately 1.5 weeks). She did not specify that special development or any enlargements were desired. A set of color positive prints ("jumbo size") and the developed color negatives cut apart into sets of two frames were received by the photographer on or about October 26, 1981. Inspection of the attached second frame to the one in question by the author showed that it was of a child standing inside a home. This child was the daughter of the couple who owned the camera; the scene was confirmed to have been taken inside their home in Campbell River, British Columbia. This fact agreed with the story told by the couple concerning the sequence of events of their automobile trip to the north end of Vancouver Island and return and the photographs they remembered taking.
It was not until the couple had received the set of color prints from the Vancouver processing laboratory that they noticed the strange aerial disc in the clear blue sky near the mountain top.
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