There is another catch on using FF lens on the APSC. The APSC sensor has a multiplication factor of 1.61 linear or 2.59 area. In order to fully utilize the resolution power of the APSC sensor, the FF lens must have 1.61 more resolution power than what is needed for the FF sensor. M3 has a resolution of 24.2 MP. It needs a FF lens with 62.79 MP resolution to fully utilize the resolution power of the M3. How many FF lens can make that claim?? It is unfortunate that Canon does not make a 35mm f2.0 IS EF-M lens.
You need to learn how system resolution works before making patently inaccurate comments like that.
Here is a start: http://www.canonrumors.com/forum/index.php?topic=26938.msg595091#msg595091
Thanks for pointing it out. I am fully aware of that. As per your quote says. When both sensor and lens resolution are matched. the end resolution is only 71%. If the lens resolution is only 66% of the sensor. The end resolution becomes only 55% of the sensor. That is 21 % reduction from the potential resolution. This is not fully utilize the resolution of the sensor. We spend money to buy expensive equipment, we want to get the most out of it.
How is it that, as you imply, your argument applies to FF lenses used on APS-C cameras, but not APS-C lenses used on APS-C cameras? Or do you believe that APS-C lenses intrinsically deliver higher resolution? Sorry, but I can't really see any relevance to your point in this discussion of using FF lenses on APS-C cameras. Yes, smaller pixels benefit more from higher resolution lenses, but the pixels of the M3 aren't all that much smaller than those on the 5DsR (same density as a 20 MP APS-C sensor).
If anything, since lens resolving power is generally highest in the center and drops toward the periphery, the benefit from using only the center of the FF image circle is quite significant – a glance at the 35/2 IS MTF chart shows resolution remains quite high through area of the APS-C sensor.