Vario-Elmar-S 30–90 f/3.5–5.6 ASPH. in Action
Nine of the 14 elements in four groups are manufactured from glasses with anomalous partial dispersion. Of these, three are fluoride lenses with particularly low dispersion for the correction of chromatic aberrations.
Two aspherical surfaces on the rear element are employed for the minimization of monochromatic aberrations, while another aspherical surface on the front lens of the second group maintains consistent imaging performance at shorter distances and contributes to the minimization of distortion.
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 35 mm 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 27.04 mm is the radial distance between the edge and the middle of the image field for the format 30mm x 45mm.