While these are compelling reasons for considering Leica cameras and lenses, their sensors do set themselves apart from the competition also. Instead of participating in the pixel race, Leica and their sensor manufacturer have done a remarkable job of optimizing sensor performance. Not until recently did Leica offer a few of their models with a sensor resolution greater than 24 MP and even now, the majority of their cameras offer a resolution of 24 MP.
Compared to other companies, both the Leica M and S line of cameras seem to be lagging behind some of the cameras of their competitors. However, that does not at all translate into lesser performance and capabilities and their competitors are aware of this as well. Until recently, most high end cameras on the market had settled on a pixel count of approximately 20 to 25 MP. But the Leica sensors differ in several respects, all of which are designed to optimize performance. Besides, what is really gained by a higher pixel count?
Take the old Leica S sensor for instance. The difference between the 37.5 MP sensor of the Leica and a 50 MP sensor is only 10 – 15% as far as the increase in linear resolution is concerned. Is that really enough of an increase compared to the other advantages of the Leica MAX 24MP CMOS Sensor as used in the Leica M? Let’s take a closer look.
This can easily be verified. Several other camera manufacturers allow the use of Leica M lenses on their cameras. Take the Sony A7r for instance. Mount a Leica 18mm Super Elmar-M ASPH on the Sony and take a few test shots. Then compare those to the results obtained from a Leica M. The difference is more than obvious. But it doesn't even require an extreme wide angle lens like that. Take a 35mm Summilux ASPH, and you will find similar difference. The Sony sensor just isn’t capable of handling non-retrofocus lenses anywhere near as well as the Leica M does.
However, it must be noted that some of the drawbacks and disadvantages described can be overcome by electronic trickery. Take modern mobile phone cameras for example. They naturally have rather small sensors because of the size of the phones. Yet their performance level is actually quite remarkable. We have even seen mobile phone camera with rather high pixel counts of 40MP or more. Yet with all the electronic wizardry, none has ever come close to the performance of a good full frame or even APS sensor size camera.
Therefore, when it comes to selecting a high performance camera system, one has to consider the draw backs of trying to overcome physical and optical disadvantages with electronic “band aids” and one also has to take into consideration if a gain of a few pixels per inch in linear print resolution is more important than the long list of advantages gained with a Leica MAX CMOS sensor.