Originally Posted by globobock
A user at a German photographieforum explained to me that the M-Series had microlenses applied at the sensor to specifically enhanced the Performance of the M-mounted lenses. Thus the lesser Performance IQ-wise if you use M-Lenses on non-M cameras.
I still have to dig deeper on this Topic.
In the beginning I thought the same; that my M lenses appeared to perform better on my M bodies versus the SL.
However, after a few hundred shots on the SL + M lens combination I found that I really couldn't tell the difference, especially after going through my usual workflow in Lightroom. I didn't have to process my images any more or less on M bodies versus the SL. And unless I truly subjected it to Sean Reid-level testing, pixel peeping at the center and edges over months, I no longer believe that my M lenses perform any less well on my SL.
The EVF of the SL is a magnificent thing of beauty. You've got to look through it to appreciate it. It's incredible. People who found it challenging to focus the Noctilux at f/0.95 and 3.3 feet found that they don't even need the 5x magnification to nail critical focus.
I suspect that any differences perceived can be chalked up to subjective preferences. Like the tired old debate when Leica switched from a CCD to a CMOS sensor. Now the SL (and the medium format S line, as well as the Q) uses the Maestro II processor, versus the M's Maestro I processor. Are there real differences? Probably. But the real question is whether you can work around it, or make it work for you. I use my M's and my SL - and my Q and my X-U, and my Canon 5DMk3 - depending on what I plan to photograph, for specific occasions and situations, and for whatever I feel like. I get different forms and levels of joy when I use different gear, but what ultimately matters is the image and the emotion.
Happy to talk technical differences but at the end of the day I simply make the gear work for me, and I'm pretty happy with the current kit. Which is not to say that I've been happy with all of my choices - for example the Sony RX100 mk3 didn't work for me. But that's another story...