Auteur: Marc Genevrier
Date: 25-09-2002 14:51
Bonjour Emmanuel. Voici ce que Rodenstock dit de sa série Apo Sironar Digital, qui me paraît la plus utilisable en rollfilm, pour des raisons de couverture.
Due to the relatively small formats on the one hand (higher diffraction!) and the high light requirements of the CCD image sensor on the other, digital photography does not allow the cameras to be stopped down as much as in conventional large- format photography. As a result, these lenses have been optimized to a working aperture of 8 to 11.
Because both the surface of the chip sensors and the area scanned by the CCD line sensor have greater planarity than conventional roll and sheet films, special attention was given to the correction of the curvature of field. The freedom from distortion, which is so important for product and building photography, and the uniformity of illumination are also excellent.
Par curiosité, voici le même texte pour la série "HR", qui ne couvre que les capteurs de 36 mm à 8 et 11, mais qui annonce tout de même un cercle d'image de 150 mm à 22 :
The Rodenstock Apo-Sironar digital HR was developed for special applications with extremely high resolution CCD chip cameras and CCD line scanner cameras with pixel sizes of < 10 ?m such as can only be realized with smaller digital camera formats. This lens utilizes every technological possibility to get as close as possible to the absolute limit of diffraction- determined resolution. Among other things, even the optical properties and the thickness of the CCD protective glass were taken into the equation of the optical correction.
The resolving power of the Apo-Sironar digital HR is not only a little better for the working apertures of 8 to 11 recommended for other high-performance lenses. You can rather see an increase in performance even with a higher aperture right up to the maximum aperture 4. This increase is reflected in the very high brilliance and detail reproduction. To ensure that this fantastic quality is not impaired by diffraction, the HR lenses should always be stopped down as little as possible.
Il y a donc des contraintes, mais s'ils sont vraiment exceptionnels à 11, ils devraient encore être très bons à 16 ou 22, non ?
Marc
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