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If a photographer needs more than one lens in the range from 300 to 800mm, cost and weight may become quite high. The Apo-Telyt-R module system has been designed to reduce cost when investing in a selection of long focus lenses.
This range of focal lengths allows for really exciting andand fascinating photography. Anyone who has used binoculars with a magnification of eight or ten times, will recognize the pleasant chock of surprise when being able to see subjects at a larger distance with great clarity and full of intriguing details. "Impossible" pictures are within reach of the photographer using the module system. As with binoculars, one learns to search for subject details and image composition with a very narrow angle of view, which is a kind of visual discipline one has to appreciate and get accustomed to.
The normal optical system (the lens with a fixed focal length) has a fixed number of lens elements, and all of them have a fixed distance between them. A zoom lens has a fixed number of lens elements, but here the distances between elements can change. A third category of designs is the multi-configuration design. Here the number of lens elements do change, but the distances between them are fixed. The Apo-Telyt-R module system belongs to this last category. The multi-configuration design has nothing to do with the so-called convertible lenses (Satz Objektive). In this latter design we encounter two lens elements or doublets (A and B) with almost identical specification, but different power of magnification, that can be used together or separately, delivering three possible configurations (A, B and AB) and therefore three different focal lengths.
The starting point of the Module system was the layout of the Apo-Telyt-R 280 mm f/2.8 and Apo-Telyt-R 400 mm f/2.8. The former has a front group of three elements and a second group of 5 elements. The 400mm system has a front group of four elements, a middle group of two and a third group of 5 elements, including the lens group for the internal focusing. If we cut both lenses in two segments and regroup the front and middle section of the 400 lens, we see the contours of the module system. The three element front group of the 280mm lens becomes the smaller module head with 125mm diameter. The rearranged first and second group of the 400mm become the larger module head with 157mm diameter. The focus module 2.8/280/400 is derived from the last group of the 280mm lens. And the focus modules 4/400/560 and 5.6/560/800 are derived from the rear group of the 400mm lens.
All combinations of the module system can be used with the Apo-Extenders and in theory you could create a 1:11/1600mm lens. But this combination is beyond the usability limit. Most photographers accept a 1200mm lens as the most extreme focal length for photographic purposes. Up till now I have used the generic term of long focus lenses to describe all lens designs with a focal length above 300mm. To be more precise, I have to add that the Module system is a telephoto design and falls in the category of super-telephoto lenses. All lenses with telephoto design have a physical length that is less than the focal length. But in the case of the Module system the lens units are really compact. The 800mm as example has a length of only 442mm. The small size helps making pictures in severe weather conditions as the low wind resistance profile reduces shake and vibrations. The design of a multi-configuration system has been described above as a kind a simple task. In reality this design is exceedingly difficult and must be done for a large part by hand. In this case the computer plays a relatively minor role in optimizing the system. The designer of the Module system had to study and experiment to find the best solution that had to searched for in a long and laborious process.
This unique modular system covers the range from 280 to 800 mm, and, with the LEICA APO-EXTENDER-R 2x even up to 1,600 mm. This can be used to replace a range of fixed focal length lenses. As a result, two lens heads and three focus modules instantly create six APO lenses, all providing consistent top-class optical quality. In the telephoto range especially, the system enables extraordinarily clear images with high contrast, exquisite detail, and accurate color. And because even the most minor of mechanical weaknesses can seriously impair performance in this range, the Leica modular system is manufactured and assembled to extremely tight tolerances. Nature and animal photographers in particular, who use multiple focal lengths in this range, will especially appreciate the system for many reasons: because the combination of one lens head with two or three focus modules saves space and weight, and because the smooth, easy focusing action results in very precise adjustment that helps in placing the plane of maximum sharpness exactly where you want it.
This lens head can be used to create 280, 400 or 560mm lens in conjunction with the appropriate focusing modules.
