Summary: A camera sensor samples the image that is produced by the lens. The sampling frequency is determined by the photosite pitch of the sensor. In the hypothetical case where a lens is producing images of black and white line-pairs without blur, it is shown that the sampling frequency must be at least four photosites per line-pair in order to recover both the frequency and original contrast of the line-pairs. That is twice the Nyquist sampling rate. Higher sampling frequencies more faithfully reproduce the image formed by the lens. In the case of line-pairs of a given frequency, the edges of the lines become sharper with higher frequency sampling. Published resolution data for the Zeiss 55mm f/1.4 Otus lens on the Nikon D800E are discussed with regard to theoretical limits based on sampling frequency. A case is made that resolution is sensor-limited in that test.
Key words: resolution limits, line-pairs, sampling frequency, Nyquist rate, Nikon D800E, Zeiss 55mm f/1.4 Otus, photosite pitch, sensor-limited, lens-limited