Can someone direct me to a link showing that the most recent sensor replacement is a CCD sensor. I am under the impression that it is Cmos and as close as they could come to the CCD rendering.
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CCD vs. CMOS has nothing too do with rendering. Creating electrical charge from photoelectrons and and converting that charge into DC voltage is not going to affect rendering.[1]
However, the sensor color-filter array and IR filter bandwidth characteristics, the sensor micro-lens optics and the camera read noise statistics (not noise levels) could impact rendering perception. That is, the information content for spatial array of DC voltage levels covered to binary values can be quite different.
Consider, with CCD or CMOS, all you have to do is use lenses with radically different optical designs to affect rendering aesthetics.
Anyway, the new M9 sensor assembly uses an old-fashioned CCD photo-diode array sensor bed. Obviously the new IR filter layer material is different. I don't think there's any data on it's bandwidth characteristics. One could speculate modification to the color-filter array materials could compensate for any rendering differences in the IR filter characteristics.
I think it's clear Leica spent significant resources trying to minimize rendering differences been the new and original M9 sensor assemblies.
1/ CCD and CMOS photos-diodes have frequency response differences. These differences occur just outside both ends (red and blue) of the the visible spectrum. These differences are typically much smaller than differences in CFA and IR filter charcateristics.