That is laughable for several obvious reasons, first, they are saying the Ziess lens is perfect and causes zero resolution loss, that is impossible, it is either breaking the laws of physics, or their measurements are suspect yet again. And, just read any Nikon forum where people own both, and there are a surprising amount, they will tell you that is simply not true, yes the E does resolve slightly more, but 30% more, no.
Not exactly perfect. just able to use the full resolution of the sensor.
If they sensor was 8 MP and a lens resolved 8, would you call that perfect? Just pushes the limit of the sensor.
No that isn't how it works, there is a complex relationship between each individual elements efficiency and a systems efficiency. Pretty much all lenses can actually resolve way more than any sensor, just look at the difference between a lens optical bench tested lens and one that relies on a camera sensor, huge difference.
So if the sensor was a 20MP sensor and the lens and sensor were both perfect then you'd expect to get 20MP of resolution, this is what DXO are claiming for the D800E and Zeiss 135 combo. However if we ignore all other factors and the lens is only 99% perfect it can only possibly resolve 99% of a perfect sensors resolution, and no sensor/camera is perfect. So the perfect sensor and 99% perfect lens could equate to 19.8MP in a simplified form.
For the full equations look here under "System Resolution": http://en.wikipedia.org/wiki/Optical_resolution
(Note, this response is for the benefit of everyone, it is not just a reply to PBD):
I wouldn't necessarily say it's complicated, but total optical system resolving power is non-obvious.
One thing, "perfect" resolution
actually means "infinite" resolution. The resolving power of an optical system (i.e. a whole camera with lens and sensor) is limited by the resolving power if the least capable component. If that is the sensor, then resolving power of the whole has an asymptotic relationship with the resolution of the sensor.
I think it's tough to say that a lens resolves 99% of "perfection"...since perfection requires infinite resolving power (at an infinite aperture, to be explicit). What is 99% of infinity? Lens resolving power is also non-linear...it falls off as the aperture is made smaller. Lens bench tests often test at max aperture and at f/8, but that is not guaranteed. So one must be specific when discussing resolving power of a system.
If we have a lens at f/4, and that lens achieves the maximum diffraction-limited resolving power, it resolves 173lp/mm. A theoretical 8mp APS-C sensor would resolve about 80lp/mm. The resolution of the whole camera, lens and sensor combined, can be closely approximated by taking the RMS of the minimum resolvable spot for each, and converting back to lp/mm. The lens resolves a spot of 2.9µm, the sensor a spot of 6.2µm. The two when working together convolve
to produce a spot size of 6.85µm, or a system resolution of 73lp/mm. The two together resolve LESS than the resolving power of the least capable...in this case, the sensor.
If we dice all the pixels in our 8mp sensor into quarters (make the pixels half as large), we end up with a 32mp sensor capable of resolving 161.3lp/mm. Combined with the same lens, the system resolution is 117lp/mm. If we make a sensor with the same resolving power as the lens, we have a 39.7mp sensor. The resolving power of the system is 122lp/mm. We are still short of the 173lp/mm of the lens. We haven't actually achieved "perfect" resolving power, despite increasing the resolution of our sensor. You never can...as you increase the performance of one component or the other, the bar just keeps getting higher...the mechanisms that convolve the image signal into the final output are constantly working against you, keeping you from actually achieving the real potential of either component. You would have to RADICALLY increase the performance of one in order to approach the limit of the other. To actually resolve the 173lp/mm spatial resolution possible with an f/4 lens, you would need pixels smaller than 0.25µm, or 250nm in size. That is smaller than the wavelengths of all visible light! It's even smaller than near UV, getting into deep UV. A sensor with pixels that small would be a 5.34 GIGApixel sensor! And that camera would still resolve 171.7lp/mm...it's still falling short of the 173lp/mm theoretical maximum of an ideal f/4 lens.
The only way to achieve perfect resolution is to have both a lens and a sensor with infinite resolving power. Obviously, such a lens does not exist. The best you can hope for is diffraction limited behavior
at a lens' maximum aperture. Few lenses achieve diffraction limited behavior at f/4, most still have a small amount of optical aberrations, especially around the periphery. The Otus is one lens that approaches ideal performance pretty closely, though.