The Rodenstock APO-Sironar Digital HR Series of Lenses are developed for special applications requiring extremely high resolution CCD chip digital backs with pixel sizes as small as 5 µm 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 and lateral chromatic aberration have been optimized to ensure that the resulting lack of sharpness or the color fringes do not amount to any more than a tiny fraction of the pixel size (which can no longer be resolved). As a result, even when the digital photos taken with the lens are enlarged to a maximum on the screen, absolutely no color fringes are visible, unless color fringes are added by the pixel structure of a one-shot back used or due to interpolation.