The pixel size of digital sensors cannot be reduced at will without an increasing image noise and decreasing dynamic range. For this reason, larger sensors for professional digital backs providing for an ultimate resolution (currently up to approx. 60 megapixels) have been developed. The digital lenses, designed for smaller sensor formats, with an image circle around 70 mm, hardly allow sufficient camera movement when applying such large sensors. That is why we developed the Rodenstock lens series HR Digaron-W with image circles from 90 mm up and an almost diffraction limited high resolution. Whenever applying these lenses, the lens swing and tilt should be utilized in order to increase depth of field. So you will have to stop down less and avoid the undesired decrease of sharpness due to diffraction.
At the moment this series includes the focal lengths 32 mm, 40 mm, 50 mm, 70 mm and 90 mm (both last-mentioned lenses Apo-Sironar digital 70 mm f/5.6 and 90 mm f/5.6 already met the high demands of the new concept and have been re-named as HR Digaron-W). As the MTF-curves (indicating 80 line pairs per millimeter from now on) clearly demonstrate, the lenses of this new series almost meet the high standards of the superior HR Digaron-S series, even if their image circles for larger sensors are much larger. Also in this case it is the improved correction of curvature of field and the integration of the sensorís cover glass into the optical design in order to eliminate spherical and chromatic aberration and astigmatism, providing for excellent, nearly diffraction limited images. The high tech multi-coating, adapted to the type of glass, provides for ultimate transmission, excellent contrast and freedom from ghost and flare.
The image angle of the HR Digaron-W 40 mm f/4 with a 37 x 49 mm sensor corresponds to that of a 28 mm lens for 24 x 36 mm sensors; with a 40x54 mm sensor it even corresponds to that of a 26 mm lens. Its back focal length of approx. 25 mm leaves free space between the rear mount and the sensor for shift and tilt movement without touching the sensor or the rear standard. The flange focal length of approx. 70 mm allows focusing at infinity for all technical cameras with a flat lens board, which makes it much easier to set the aperture and the shutter speed and permits the use of the Rollei Electronic shutter. The retro-focus design causes a steeper light incidence at the margin. So the further fall-off in illumination, which is inevitable when using microlens sensors, can be avoided.
Further focal lengths are in preparation.