Leica S2: the lenses: a litmus test
In the previous part I concluded from the technical analysis that Leica has been able to position the new S-system at the top of the medium format league. Some readers remarked that it was unfair to compare new lenses with older Zeiss lenses for the H-system. That is a point well taken. The current lenses for the PhaseOne, Mamiya, Pentax and Hasselblad digital systems generally do follow the design parameters of the classical Zeiss lenses. In this perspective it makes sense to compare the design philosophy of Leica with those of the competitors. A second point is the influence of the sensor size. You might argue that the introduction of 50Mp and 60 Mp sensor sizes will redraw the medium format landscape again. But the law of diminishing returns does work. The jump from 18 Mp (Leica M9) to 24 Mp (Nikon D3x and Sony 900) to the 37.5 Mp of the S2 is visible but the improvements in quality are slowly becoming academic and the need for image files based on 60 Mp capture systems is limited, if you are able to see the differences. More on this theme in the next part.
In this article I will present a number of actual pictures to deliver proof of the capabilities of the S2 system and lenses. The method I used is the same for all pictures presented here. Leica has stressed the fact that the S2 images do not need a large dose of postprocessing as the basic RAW files are already excellent. The logic is compelling: a professional photographer should be fully confident in the capabilities of the system and spend most time in taking pictures and not in manipulating image files.
All pictures presented here are sections of the RAW DNG files developed with the new final version of Lightroom 3. The pictures are not manipulated in any way, no exposure or color corrections and no sharpness manipulations. It is always possible to improve on any one of these pictures, but for comparison purposes all processing is identical. The only exception are the black&white portraits that were based on the raw DNG files with Lightroom presets. All DNG sections were converted to JPG by the Lightroom engine.
Many users of the M8/9 system have observed that the impression of the images is flat and lack the visual depth of chemical prints and slides. This difference is indeed one of the reasons why film is still in demand. The plasticity of round objects in a scene, the subtle tonality in the highlights are characteristics of film not easily found in digital files.
The S2 images did strike me as being as close to film-based pictures as I have ever noticed. The S2 system is quite close to implementing the Kodak E-6 strategy: take the picture, develop in E6 and present the slide.
The general quality.
The Summarit-S 70 and Apo-Elmar-S hardly improve when stopping down and have a very even coverage over the full image area. Below is the test chart that has been used to check the claim.
The images are selections from the center star and the upper left corner star. The performance of the Summarit wide open is excellent with only a slight drop in contrast and definition at the edge.
At f/5.6 the center and edge performance shows a higher level of crispness, but the edges are still faintly lower.
The same pattern is seen in the Apo-Elmar-S performance. The slight loss of contrast at the edges is also seen in the MTF graphs. I should stress that these differences, while visible in the test pictures, loose much of their importance in actual picture taking.
The quality of the image as far as definition is concerned stays on a very high level when higher ISO values are used. See the picture below of the center part at ISO1250 with the Summarit-S at f/5.6. The noise pattern is on the other hand clearly visible: see below the comparison of a patch at ISO160 and ISO1250.
Pictures at various ISO values indicate that for critical work ISO640 is the maximum. But even that speed is very high for a medium format camera.
All image sections at 100%!
Below: Summarit-S f/2.5 center
Below: Summarit-S f/2.5 edge
Below Summarit-S f/5.6 center ISO 160
Below Summarit-S f/5.6 center at ISO1250
Below Summarit-S f/5.6 edge
Below Apo-Elmar-S at f/3.5 center
Below Apo-Elmar-S at f/3.5 edge
Below Apo-Elmar-S at f/5.6 center
Below Apo-Elmar-S at f/3.5 edge
ISO160 versus ISO1250
Below are two images of a selection of the test chart with grey patches from white to black. The differences are quite visible, but for ISo1250 and fully unprocessed in post processing, the quality is certainly not bad.
Below ISO 160
Below ISO1250
Vignetting.
The Summarit-S wide open hardly has any light fall off in the corners. The image below exhibits a faint shadow in the extreme corners, but that is all. The Apo-Elmar-S does not show any vignetting which is not surprising.
Flare.
Is it always possible to force a system to exhibit flare. Here you see an extreme example with the Summarit wide open. This is a really demanding situation where thin branches are exposed against the clear sky. The light rays spill over into the dark parts. Section of the image at the outer edge. It has to be added here that this behavior is not caused by the lens itself but by the total system processing.
Close up.
One of the claims of Leica is the excellent close up performance. The pictures below show that this claim is substantiated. The pictures were made at closest distance (70cm) wide open and stopped down to f/5.6. Examples are from center and upper right part. This performance is really commendable and at this moment unsurpassed.
FIrst the total scene.
Summarit-S f/2.5 close up center
Summarit-S f/2.5 close up edge
Summarit-S f/5.6 close up center
Summarit-S f/5.6 close up edge
Note that the performance does increase when stopping down, but not by much.
The test box
Below an image of the test box used to check the performance. This is a quite exacting test as it forces the lens to perform at its best. It has areas where moire is seen, dark parts and specular highlights where the dreaded purple rims can be detected.
Moire is not visible in the Summarit and not in the Apo-Elmar-S.
Below Summarit-S
Below Apo-Elmar-S
The Summarit-S wide open and stopped down to /5.6 offers outstandingly good behavior in highlights and specular spots. One is hardly aware that one is looking at digital images. At high ISO values (1250) there is a certain softness and graininess in the image. Color rendition and drawing of fine color tones is immaculate.
Below Summarit at f/2.5
Below Summarit at f/2.5
Below Apo-Elmar-S at f/3.5
The Apo-Elmar-S wide open has a cleaner and crisper image compared to the Summarit-S, but again you need a direct comparison and a critical eye to detect it. The A-E-S stops down to f/32 and you may ask whether this aperture is useful. It is with some loss of contrast. See the text string in the middle of the test chart. Note too that the difficult rendition of rounded characters is very good. There is not the slightest indication of rough edges at the curves.
Text at f/3.5
Text at f/32
Below Apo-Elmar-S at f/3.5
Below Summarit at f/5.6 at ISO 160
Below Summarit-S at f/5.6 at ISO1250
Portraits.
Below you find a series of portrait pictures. They are made with the A-E-S 180. More pictures with the Summarit-S 70 in the next part.
Below the full picture, below that a look at the lips. See how natural the gloss is, the skin tone and the detail.
A second example. THis one with flash. Note the sparkle of the make up above the eye and the fine structure of teh hair.
Below a close up wide open. Note how the sharpness plane can be selected when using manual focus.
These examples above give you an idea of the performance of the S-sytem and its ease of operation. Just shoot the image, develop without any manipulation and print.