Street, portrait, or whatever catches your eye: Conceived as a universal lens for any situation, the APO-Summicron-SL 75 f/2 ASPH. opens up new horizons for photography in the versatile zone between standard and telephoto focal lengths. It is perfectly matched to the cutting-edge SL-System and has been designed for a long life under a heavy professional workload. In addition to this, the maximum reproduction ratio of 1:5 contributes even more to the versatility of the lens, allowing for close-up shots that pop with punchy sharpness and definition.
AF System with Dual Syncro Drive™
From zero to sharp in no time at all
The autofocus system shared by the Summicron-SL lenses is fast, precise, and nearly silent. Their outstanding AF performance figures are thanks to the autofocus drive unit they both utilize. These are limited only by the mass of the glass elements moved when focusing; the speed of moving from infinity to the closest focusing distance. In order to preserve the compact dimensions of the lenses, the integration of these components must be perfectly optimized within all design constraints.
Specialists from the areas of optical engineering, mechanical engineering and electronics worked together as an interdisciplinary team on the development of a unique lens concept based on double internal focusing. This system, comprising two especially light focusing lenses, allows the construction of particularly small and compact drive systems. While being able to work within tight space constraints, the drive motors used must maintain peak performance in all situations to be chosen for such a cutting-edge camera system.
Several contrast measurements at various focusing positions must be made before the correct direction for focusing can be determined and followed by precise focusing. In this procedure, the focusing lens elements must be moved rapidly in accordance with the speed specifications of the contrast AF system. This requires a dynamic drive system without any room for error.
In the Summicron-SL lenses, the drive units installed are extremely powerful and robust stepping motors with Dual Syncro Drive™. Thanks to these, the entire focusing range can be traveled completely in fractions of a second. This means that the Summicron-SL lenses achieve values that are among the best in the full-frame system segment in terms of speed, precision, and operating noise.
for greater visual depth
With a maximum aperture of f/2, the SL-Summicron lenses are significantly more compact than even faster lenses, but still allow photographers to work with similar depth of field. The reason for this is contrast: the area of highest contrast is incredibly sharp, while zones with lower contrast are unsharp or beautifully blurred.
In the case of SL-Summicron lenses, this difference in contrast is considerably higher than that of conventional lenses: sharply focused objects show much higher contrast than objects that are out of focus. This means that objects “pop” more distinctly out of the foreground or background and more effectively isolate the subject. This creates a three-dimensional visual effect with very impressive depth.
Optically and Mechanically
a new standard
In the construction of the Summicron-SL lenses, particular attention has been paid to the prevention of stray light and reflections. The optimization of the optical and mechanical design was carried out in elaborate simulations before the construction of the first prototype lenses. Unavoidable reflections are reduced to the lowest possible level by high-quality optical coatings of the lens surfaces.
for uncomplicated handling
The three most obvious functions of a Summicron-SL lens to its users – auto focus, the manual focus ring, and aperture setting – are all based on a multitude of control systems and mathematical operations. The demands on the electronics are particularly high in the case of the double focusing system. Here, the two autonomous focusing motors must be moved in perfect synchronization and positioning data must be analyzed at a very high sampling rate and passed on to the camera.
The electronic communication between the lens and the camera is so fast that there is no perceptible delay in performance. These are the primary preconditions for fast and precise contrast autofocus.
A ring magnet with alternating north-south magnetization is embedded in the manual focusing ring. The magnetic field changes its polarity when the ring is turned. A sensor monitors the status of the magnetic field and sends the data to the main processor. The drive then shifts the lens to the corresponding focusing position on the basis of the angle of rotation and the rotational speed.
The iris is driven by a stepping motor. Here, a special micro-step control system ensures precise and fast movements with minimized vibration.
down to the smallest detail
The consistently compact dimensions, low weight, and the excellent grip and feel of the SL-Summicron lenses are particularly impressive when shooting. Thanks to the nearly identical design of both Summicron-SL lenses, with similar center of gravity and handling, users will feel at home when switching between the two without any adjustments needed. The lenses balance the camera nicely, for both a more comfortable handheld shooting experience and easier steadying on a tripod.
The optical system of the APO-Summicron-SL 75 f/2 ASPH. is comprised of 11 elements, one of which has an aspherical surface. A very high proportion of these elements is manufactured from specially formulated, high-quality glass types for the correction of chromatic aberration. Their particular optical property, so-called anomalous partial dispersion, enables compensation for chromatic aberrations resulting from the other glasses in the optical system. As a result of this, even highlights in images remain almost completely free of color fringing.