Leica 90-280mm f/2.8-4 APO-Vario-Elmarit-SL Lens

Leica Camera is pleased to introduce the Leica 90-280mm f/2.8-4 APO-Vario-Elmarit-SL Lens which provides quiet, precise and fast auto focus in a versatile high-performance telephoto zoom. The lens combines an extended range of telephoto focal lengths and extremely good performance, from the infinite setting right up to close-up, with open aperture just as much as when stopped down. In this way, with its shutter speed that is only slightly slower than that of fixed focal lengths, it can increase the photographer's flexibility, e.g. in areas such as travel and reportage photography just as much as portraits and close-ups.

The Leica 90-280mm f/2.8-4 APO-Vario-Elmarit-SL's image quality is incredibly well optimized and corrected at every aperture and focal length, yielding sharp results in any environment. By utilizing unique double internal focusing with floating lens elements, the lens achieves fast auto focus throughout this zoom range while all movements are done within the lens barrel. The lens does not change shape or size while zooming or focusing, allowing for better weather resistance.

A lockable rotating tripod collar allows the lens to be fixed at any angle. The collar has detents every 90 degrees for rapid switching from landscape to portrait format. The lens hood supplied with the lens suppresses undesirable reflections, stray light, and prevents flare.

AF System with Dual Syncro Drive™ - From zero to sharp in no time

The AF system of the Summicron-SL lenses is fast, precise, and almost silent. They thank their outstanding AF performance figures to the autofocus drive unit they share. These are limited only by the mass of the lens elements moved when focusing, the travel from infinity to the closest focusing distance and, of course, the amount of space available. In order to preserve the compact dimensions of the lenses, the integration of these components must follow an integral approach.

Specialists from the areas of optical and mechanical engineering and electronics worked together in an interdisciplinary team on the development of a unique lens concept based on double internal focusing. This system, comprising two particularly light focusing lenses, allows the construction of particularly small and compact drive systems. In addition to space limitations, the choice of the drive motors is also determined by the AF principle used for focusing.

Several contrast measurements at various focusing positions must be made before the correct direction of motion for focusing can be determined and followed by precise focusing. In this procedure, the focusing lenses must be moved rapidly backwards and forwards in accordance with the speed specifications of the contrast AF system. This requires a dynamic drive system without any play.

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 throw 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 noise emissions.

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 best possible level by high-quality coating of lens surfaces.

Complex Electronics for uncomplicated handling

The focusing and aperture setting functions of a SL-Summicron lens are 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.

The two autonomous focusing units must be moved in perfect synchronization and positioning data have to be analyzed at a very high sampling rate and passed on to the camera. Here, the communication with the camera is so fast that there is no perceptible delay. These are the primary preconditions for fast and precise contrast AF.

The aperture is driven by a stepping motor. Here, a special micro-step control system ensures precise and fast movements with minimized vibration.

Manual Focusing - A new experience

SL-Summicron Lenses feature a totally new manual focusing ring construction concept. In this concept, 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 construction of the MF-ring guarantees reliable sealing against dust and water spray, provides protection against impacts and other mechanical stresses, and prevents focusing inaccuracies as a consequence of temperature fluctuations. Even after years of use, the MF-ring of a SL-Summicron lens impresses with a smooth action without play and homogeneous focusing.

Constructional Details

Of the 23 elements in seven moving groups, seven are made from glasses with anomalous partial dispersion for the minimisation of chromatic aberrations. The movement of the two focusing elements is provided by a newly developed drive concept with linear positioning of the lenses by stepping motors. A special feature of this is that the overall length of the lens does not change when either focusing or zooming.