LEICA

Alternative views on the Leica world by Erwin Puts

The Leica X Vario is a smart combination of Japanese gadgetry and minimalist solid German engineering. The X Vario can be viewed as a high-performing compact mirror less camera or as a companion to the M series. The first view would draw attention to the fact that the X Vario has a very potent combination of a large APS-C sized sensor combined with an excellent optical system. The high MTF values at the 60 linepairs/mm and the total absence of chromatic errors (color fringes at the edges of lines with high contrast gradients) give the camera a definite lead. The sensor size of the 35mm format is at the moment the benchmark for high resolution photography. But the APS-C sized sensor has the advantage of smaller size and lightweight bodies. Leica has designed an APS-C system that performs in the 35 mm class. The high MTF at 60 lp/mm compensates for the smaller sensor size and the final results are quite comparable to 35mm. In this area the X Vario can challenge the performance of the M. The zoom range from 28 - 70 mm (related to 35mm) seems a bit meagre, but the 60 lp/mm allow for a 141% enlargement, bringing the focal length to a useful 90mm. 


The second view would note that the X Vario offers functionality that is lacking in the M. An efficient autofocus system, a smooth vario lens, and a close-focus range to 30 cm are precisely the areas where the M has to drop out. 
If Barnack would have lived now, he would probably have designed a camera like the X Vario. A compact, lightweight, elegantly designed, high performance camera that could be used all day for recording interesting and memorable events was the goal he set himself when designing the Leica camera. This set of requirements has been realized with the X Vario.

The Leica X Vario, like the original Leica II or IIIc, invites the user to take pictures at any time. Its performance in the close-up range is excellent at all focal lengths and this feature makes the X Vario a fine companion to the M series. In fact, it might even displace the M for general purpose photography. For most intentions, the image quality of the X Vario is comparable with the results of the M series. There are a few caveats however.

When you open the DNG files in a digital developer, not being LR5, you will notice that from  28mm to 45mm (35mm conversion) there is a very visible amount of distortion and a fair amount of vignetting. These defects are fully corrected in the JPG files and in the DNG files processed with LR5. Distortion and vignetting are indeed the aberrations that do not degrade the basic image quality and it makes sense to leave these aberrations uncorrected and focus on the more important aberrations, like the longitudinal and lateral chromatic errors. The optical characteristics of the lens are now integrated with the post-processing algorithms. This is not a problem in this case where the lens is fixed to the body. It would not yet be possible to apply this approach to interchangeable lenses, but its is an indication where progress in modern lens design is heading to. By the way, at the optimum apertures of the lens and a focal length comparable to the standard 50mm lens for 35mm format, the Vario-Elmar outperforms the Apo-Summicron-M. One should however keep in mind that the Vario-Elmar has a modest maximum aperture. Everything has its price!

The Vario-Elmar is at its best from maximum aperture to about f/8, Smaller apertures show a drop in performance as expected, but the drop at f/16 is a bit high as can be seen in the graphs below. 


The approach of the X-Vario indicates that the classical ideas about lens design are fading into history. The best proof is the occurrence of distortion at the 28 mm position, that is clearly visible in the original (non-processed DNG files). See below. In the corrected files and the JPEG mode there is no trace of distortion.

X-Variodistortion

The overall performance of the X-Vario is the result of the intimate cooperation between lens design, software and sensor construction. Being conservative this fact may not make you happy, but being pragmatic the results speak for themselves. See below.

L1010563
L1010175
Particularly this last picture shows the excellent overall quality, the definition of fine textures, suppression of flare and the extremely low level of chromatic aberrations. 



Dynamic range.


The dynamic range of the X-Vario is about ten stops at ISO 100 and about 8 stops at ISO 6400. There is much hype over the value of these numbers, as there is is correlation between noise and dynamic range. On the other hand it must be noted that most printing materials can handle only about 5 stops and in these cases there is no problem with even the dynamic range of less than 8 stops. Note below that at ISO 6400 the highlight latitude is very limited and it is best to under expose.

X-VArio-DR6400

The practical results for ISO 12800 are very good and when there is much structural detail the noise impression is very much reduced.

Resolution.


Resolution figures are often seen as the Holy Grail of digital imaging. More important in practical use is the evenness of image quality over the full picture field. In this respect the X-Vario has a good record. Even at the 28mm position the edge-to-edge performance is exemplary. See below the results for 28 mm and 46 mm.

Xvario-resolution28mm




The diagram shows the MTF for 10 (orange), 25 (blue) and 50 (green) % contrast. The interpretation of these values is: 1300 LP/PH (green line) can be recorded with a limiting MTF of 50% and 1800 LP/PH (orange) can be recorded with a limiting resolution of 10% 
Compare this result with the current Apo-Summicron at f/4 on the M camera. See below.
MTF-M+ASC50

The M/ASC50 combination has the edge as expected, but again in practical photography the differences are less visible than in these test conditions.
The important difference between the M and the X-vario is the edge contrast.

Final verdict.


The X-Vario shows a very good balanced performance at all apertures, focal lengths, object distances and over the full field of the image. IT is a most versatile camera that can be used in the Leica M ecosystem without hesitation. The time lag of the shutter response is in my view the only aspect that needs fine tuning. For really fast and instant street photography the response is frustratingly sluggish, but this is a common defect of all digital cameras. The Film-loading M cameras are still unequalled in this respect. The short range of the vario lens, especially the limit to the 70 mm position has often been complained about. I do not share this complaint. The fact that the lens is fixed to the body has the additional advantage that there can be no dust inside the body and the range from 28 to 70 is quite flexible and conforms with the optimal Leica M range from 28 to 75 mm.