Leica SL, part 1

The original Leica had three important characteristics: (1) is was smaller than everything the competition could offer; (2) is was precision-engineered with a metal body, where precision implied that the overall tolerances during the manufacturing and assembly processes were held to a minimum, ensuring a smooth operation and high image quality and (3) was easier and faster to use than most cameras on the market, especially the medium and large format cameras of that era.
These three characteristics gave the Leica photographer a definite advantage when recording in high-definition the fleeting and emotional moments in life. When the competition incorporated full automation into the camera (starting with the Konica Autoreflex and ending with the Canon T90), Leica responded with a subtle change in their philosophy of the proper instrumentation of the photographic act with the M5, M6 and M7. These cameras added in-camera manual exposure metering and aperture-priority automatic exposure metering to the camera. The digital versions of the M camera, including the current M have not advanced much beyond this state of automation. This level is indeed the limit of what can be included in the M without losing its main profile.
The first reflex camera made by Leitz followed the guidelines of the time-honored rangefinder camera. The original Leicaflex was as close to the principles of the rangefinder camera as was technologically possible. The successors, from Leica R3 to Leica R9, incorporated new features and technologies, but could never convince the users that Leica’s approach to photography (minimum features and maximum user input coupled to high quality optics and precision engineering) could successfully distance itself from the mainstream. When the gap between the actual image quality and the build quality of the Leica products and the main competitors became so narrow as to be insignificant for most users, the only option for Leica was to capitalize on its iconic history, exemplified in the rangefinder camera. A fresh start was possible when the technology of the solid-state sensors could be incorporated into the current camera systems. The DMR for the Leica R8/9 and the Leica M8 were the first products from Leica that were often seen as an overcautious adventure into a new technological terrain. This cautious approach rested on two pillars: (1) lack of investment money and expertise and (2) fear to break up the iconic status of the Leica product line.
Gradually it began to dawn on the Leica management that a continuation of the two-pronged strategy of (1) continuous but incremental improvements and (2) capitalizing on the prestigious history as seen in the rangefinder line was untenable for a company that wanted and needed to grow to survive. The dialectics of progress demanded that the strategy of minimalism of features and emphasis on the optical and engineering competence was obsolete. The Leica T was the first new camera that tried to embrace modern technology while staying close to the heritage of Barnack. The next camera, the Leica Q, surprised the market and the loyal followers of the company with its innovative features and cutting-edge technology. This camera showed clearly that the principles of the Leica M are no longer the main guide for the development teams.
The T and Q made it abundantly clear that the technology of opto-mechatronics will be the successor to the classical precision engineering and manufacturing. This is not to say that the recently introduced Leica products, including the SL, the main object of this survey, are not build to a high standard of precision. The choice of materials and the surface treatment are second to none. It is fair to say however that the standard of engineering is one of the main criteria for the assessment of the mechanical Leica M, whereas it is secondary to the optomechatronic devices that are mainly characterized by the level of automation and level of choices of camera assistants. The increased attention for the automated functions has also changed the optical design paradigm that Leica has promoted for decades. The designs for the M-lenses are characterized by its solid mechanical construction, small size and low weight and by the use of as few lens elements as possible (a consequence of small size!). The Summilux-M 1.4/28 mm ASPH has ten elements, one floating element and one aspherical surface. The Summilux-Q 1.7/28 mm ASPH has eleven elements, two focus elements one element for optical image stabilisation (ois) and three aspherical elements (between three and six aspherical surfaces!).
The only lens currently available for the SL camera is the Vario-Elmarit-SL 1:2.8-4/24-90 ASPH. This design is a watershed in the history of Leica optical design. A lens with a weight of 1140 grams is not unusual in the Leica lens stable. The Vario-Elmarit-R 1:2.8/35 - 70 mm ASPH had a weight of one kilogram with eleven elements and one aspherical surface. The SL lens has 18 elements, five aspherical surfaces on four elements, one element for ois and one element for the AF function. There are six moving groups. The complexity of the design is partly caused by a number of factors. The inclusion of ois has a significant impact on the design parameters. The mechanism of ois can increase the residual aberrations and the design must have a complex layout that counters this possible effect. The requirement that the lens has on average an MTF of 60% for 40 lp/mm at all apertures, focal lenghts and image positions is not easy to fulfill, especially when this requirement also covers the close focus position (30 cm for the 24 mm and 45 cm for the 90 mm focal length). The aspherical surfaces are particularly sensitive to misalignments and the mounting mechanism must ensure that all elements are correctly positioned. All these demands explain why the lens is heavy and big: at the 90 mm position is has a length of 17 cm.
The camera body
The camera has an ergonomic design with an assortment of dials, wheels, knobs and menu controls. The several control elements are well placed and easy to use. The most used controls can be assigned to the six buttons (four menu buttons around the back monitor display and the buttons on top and on front of the camera for LiveView and Stopdown).
The camera has a sizeable viewfinder eyepiece with integrated diopter adjustment. In fact all control elements (the main switch, the top dial and the click wheel) are dimensioned for heavy use and easy control. The fake prism housing with the viewfinder are located off center at the left side of the camera body to make room on the right side for the top panel display. At the left side there is room for the GPS antenna. The most prominent design element is the choice for sharp-angled contours.
The electronic viewfinder is very clear and bright even in darkness. This is at first a bit strange because you see a bright image in a dark environment. The claim by Leica that the screen resolution of the EVF matches the ground-glass of normal SLR’s is indeed substantiated.
In general operation the camera is very quiet. The AF function is hardly audible and at least in the single field metering very fast. The camera needs some contrast difference for reliable focus, but the easy way of moving the field to the intended sharpness area (touchscreen or joystick) makes this adjustment a simple act. The multifield and zone focusing methods select that point or area of the motive (within the focusing area) that is closest to the camera. The resolution of the monitor screen is quite low and while it gives a very fine impression of the picture taken, it is not possible to check the sharpness, because the low resolution blurs the details. You have to trust the AF!
The internal motor drive is very quiet too. When selecting the continuous high speed drive, there is some audible noise, but still within the comfort zone.
The number of options and the possible combinations is rather high and at first a bit confusing. The two extremes are the fully automatic and the fully manual mode. In automatic mode, you select JPEG, the zone focusing, multifield metering, program exposure mode and let the camera take care of everything else. In manual mode you select DNG, manual focusing, spot metering, manual exposure control and you have to rely on your own expertise. In between there is a range of options that can be adjusted to the preferred scene conditions and shooting habits of the photographer. In many cases the options only make subtle differences that may or may not be interesting. The difference between multi-field and center-weighted metering are not always detectible as are the differences between AF zones and AF fields. The owner of the camera has to experiment to find the optimal combination or combinations and careful note-taking is necessary. More on this aspect in the next part.
The image quality is impeccable. One may complain about the unsharp background with a restless bokeh, but in general most users will be most pleased with the fact that the image quality is very constant over the full range from infinity to close focus at all focal lengths. Only at the distance setting below 50 cm one has to stop down to ensure crisp detail.
The image quality is related to the ISO speed and the noise pattern. From ISO 50 to ISO 400 the noise is not degrading the structural detail of the image. From ISO 800 the fine detail is progressively lost and the higher ISO settings of 25000 and 50000 are not useable when fine detail needs to be recorded. (pictures in the next part!).
To set the image quality in perspective, I compared the Leica Monochrom 2 and the Leica X-Vario with the SL. On the MM2 I used the Summilux-M 1.4/50 mm ASPH with the apertures of 3.5 and 5.6. The same apertures and focal length was selected on the SL and the X-Vario. Based on these results the M user may be happy: the M-pictures are better than the SL pictures and (no surprise) the X-Vario. The SL also is better than the X-Vario, but given the smaller sized sensor its performance is very commendable. I needed to enlarge to 300% to see significant differences and when we stay within normal conditions the differences are much less significant. As an aside I may remark that the SL pictures were made with AF and also with manual focus: there is no detectible difference.
Below are the three pictures. These are 300% sectional enlargements of the original DNG files. No post-processing.



In the next part I will give a detailed report of the performance of the SL and study some of the most interesting combinations of features. The broad range of movie options will be neglected because I have no expertise in these matters.