Solargrafía de un Paranal Soleado
Solargrafía, el arte de usar una sola exposición de larga duración con una cámara oscura para fotografiar el movimiento del Sol a lo largo de varias semanas, ayuda a mostrar por qué Cerro Paranal en el norte de Chile constituye el hogar perfecto para el Very Large Telescope (VLT) de ESO. La cámara oscura, construida con un pequeño tubo de rollo de películas y un pedazo de papel fotográfico, fue instalada por Gerd Hüdepohl en el techo del edificio de control del VLT desde el 15 de octubre al 26 de diciembre de 2009, cubriendo la primavera del hemisferio sur. Las rayas blancas que se extienden en la parte superior de la imagen plasman el avance del Sol a través del cielo a lo largo de todo el período. Cuando se cruzan nubes entre el Sol y la cámara, se producen quiebres en las rayas blancas pero, como vemos, no hay nubes que oscurezcan el cielo durante toda la exposición. En otras palabras: ¡el clima perfecto para la astronomía! La Unidad de Telescopio 1 del VLT es visible como un perfil fantasmagórico en la parte baja de la imagen.
La idea de crear las solografías en los telescopios de ESO provino de Bob Fosbury, un astrónomo que trabaja en la sede central de ESO en Alemania, luego de aprender la técnica de parte del artista finlandés Tarja Trygg. Éste proporcionó cámaras –básicamente cilindros con un hoyo y un pedazo de papel fotográfico sin exposición instalado a lo largo de la pared interna- y Fosbury junto con el director del Observatorio Andreas Kaufer, entregó las cámaras, conocidas como “latas” (“cans”), a los sitios de los observatorios en Chile para cuatro meses más tarde recolectarlas para su procesamiento final por parte de Trygg. “Es una imagen absolutamente única”, dice Fosbury. “Nunca había visto huellas solares intactas como éstas en imágenes de larga exposición tomadas en todo el mundo”.
Los colores que aparecen en la imagen de la cámara oscura no están relacionados a los colores reales de la escena. El color proviene de la apariencia del polvo de plata que crece en granos de haluro de plata. Con imágenes solargráficas, el papel fotográfico no se desarrolla sino que simplemente se escanea con un escáner a color normal después de la exposición y luego se “invierte” –cambia de negativo a positivo- en el computador. Esto revela la imagen latente, que en una fotografía normal usualmente es invisible y está compuesta de alrededor de diez átomos de plata por mil millones de átomos de granos de haluro de plata. Sin embargo, en exposición continua los primeros signos visibles de una imagen latente son amarillentos, para luego oscurecerse a sepia y finalmente a un tono café granate, en la medida que crece el tamaño de la partícula. Al final, la exposición máxima produce una sombra color azul pizarra.
Links
Crédito:ESO/R. Fosbury/ T. Trygg/ G. Hüdepohl (atacamaphoto.com)/ A. Kaufer
Sobre la imagen
| Identificador: | potw1011a |
| Idioma: | es-cl |
| Tipo: | Fotográfico |
| Fecha de publicación: | 15 de Marzo de 2010 a las 08:50 |
| Tamaño: | 1998 x 1196 px |
Sobre el objeto
| Tipo: | Solar System : Sky Phenomenon : Light Phenomenon : Sunrise-Sunset |
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