DxOMark, a maker of software for cameras and lenses, concludes from the test that almost half of the total sensor resolution of an slr or compact system camera to be lost due to lens or sensorfouten. DxOMark calls this the “perceptual resolution”.
The sharpness of lenses is usually determined and displayed on the basis of the Modulation Transfer Function chart, or ‘MTF’. A disadvantage of this is according to DxOMark that MTF charts are difficult to compare and they seemed to have little insight into. Only specify the resolution of the image sensor in the camera, according to the company there is not enough information due to influences, such as diffraction, optical aberrations of the used lens and a non-optimal low-pass filter for the sensor.
To provide more insight in the sharpness that is possible with a certain combination of camera and lens introduces DxOMark the so-called ‘Perceptual MPix’-unit of measure, that is, the perceptual amount of megapixels that with a certain camera-lens-combination is feasible. The term megapixels is a broader public.
Tests from DxOMark is shown that the perceptual resolution of up to 45 percent lower than the sensor resolution of the camera. As it turns out, inter alia, that by use of the Sigma 35mm F1.4 DG HSM lens on a Canon EOS 5D Mark II, with a sensor with a 21.1 megapixels, the perceived resolution is reduced to the 17.2 megapixels, and with Carl Zeis Distagon T* 35mm f/1.4 THEY even to of 15.2 megapixels.
DxOMark uses the new unit of measurement for the observed resolution immediately at the comparison of the lenses on his site. The advantage is that the sharpness of different systems with unequal sensorgroottes now much easier to compare. Also, in the future may also see the difference in sharpness between, say, a Nikon 1 with 10 megapixels and 10-30mm lens, and the Sony RX100-compact camera with the same sensor size can be compared. Now it is only a comparison between the two cameras is possible in regards to color depth, dynamic range and low light iso performance.
