SUMMARIT-S 70 f/2.5 ASPH.
The high-performance standard lens
Standards redefined
The Summarit 70 f/2.5 ASPH. (CS) (56 mm in 35 mm format) is suitable as a standard focal length for an enormous range of photographic situations and, thanks to its speed and superior imaging quality, masters them at all apertures and focusing distances.
The use of aspherical surfaces to almost completely eliminate monochromatic aberration is unusual for this focal length and underlines the exceptional character of this lens.
The highlights
Ideal standard for all photographic needs
High-performance standard lens with an angle of view equivalent to that of a 56 mm lens in 35 mm format
Innovative central shutter for maximum design freedom when using additional light
Excellent imaging performance over the entire range and at all aperture settings
Extremely fast
Creative use of sharpness and blurring for the plastic extraction of motif details
Best image quality up to the edges due to aspherical optics
Weather- and dust-sealed lens
Technical Details
The eight lens elements of the Summarit-S 70 f/2.5 ASPH. (CS) are arranged in six groups. Two cemented elements made from glasses with high anomalous partial dispersion minimize chromatic aberration, while glasses with extremely high refractive indices and an aspherical element counteract monochromatic aberrations.
The built-in front filter is an integral part of the optical design and provides optimum protection against dust and spray. In this design, focusing in combination with a floating element ensures excellent performance in the close focusing range.
Modulation Transfer Function
The MTF is indicated both at full aperture and at f/5.6 and f/8 at long taking distances (infinity).
Shown is the contrast in percentage for 5, 10, 20 and 40 lp/mm across the height of the 35mm film format, for tangential (dotted line) and sagittal (solid line) structures, in white light. The 5 and 10 lp/mm will give an indication regarding the contrast ratio for large object structures. The 20 and 40 lp/mm records the resolution of finer and finest object structures.
Distortion & vignetting
Distortion is the deviation of the real image height (in the picture) from the ideal image height. The relative distortion is the percentage deviation. The ideal image height results from the object height and the magnification. The image height of 27.04mm is the radial distance between the edge and the middle of the image field for the format 30mm×45mm.
