The focus of almost everyone is on the prestigious M lenses, like the SX 1.4/35 and the NX 0.95/50. The full range of Leica M lenses covers the fixed focal lengths from 18 mm to 135 mm (with the exception of the ‘vario’ lens Elmar 16-18-21 mm). The 135 mm is hardly mentioned at all by most reviewers. It is indeed a difficult lens to use, especially with the FPA-equipped Leica M cameras. The focal length of 135 has always been problematic in the range, because of the inherent limited accuracy of the rangefinder coupling mechanism, that was designed for use with the 50 mm lens. Even with the 1.4 magnifier the rangefinder is stressed to the limit, especially at wider apertures. This is the reason why Leica advices to use the 135 mm lens at medium apertures only when attached to a FPA-equipped body.
For a long period the 135 mm focal length was the favorite of portrait and reportage photographers, because of its ‘natural’ perspective and its ability to magnify the object at larger distances.
The 135 mm lens on the Leica provides a unique opportunity to learn the finer points of the rangefinder mechanism. When focusing the 135-lens on an object with clear-edged vertical lines it is the experience that a slight movement of the focusing mount will not change the vernier acuity of the rangefinder. In other words there is a slight tolerance in the mechanism. The solution is to look for maximum contrast in the rangefinder patch. The rangefinder reacts to contrast changes and to alignment changes. The first type of changes is the most accurate, but is difficult to detect in low contrast conditions. The best strategy is to focus with the alignment option and to do fine tuning with the contrast option.
It also makes a difference in accuracy if one focuses from infinity to 1.5 meter or from 1.5 meter to infinity.
A check with the Live View function of the MM2 indicates that the rangefinder is as effective as the Live View 10x focus peeking. Very critical focusing even indicates that the RF is more accurate than the Live View FP option.
The test with the Siemens Star shows that the distance between 2 and 5 meters gives excellent results at f/3.4 and somewhat better results at f/5.6. At infinity the lens is at its best, but then details are rather small and enlargement will inevitably produce a loss in clarity and crispness.
The lens has obviously a steeper learning curve than a 50 mm or a 35 mm, but rewards the photographer with very crisp and clean framed sections of the object of interest. The designation ‘Apo’ is fully deserved.