According to common sense, if I have an optics of let say 120 lp/mm resolution then I must select a sensor of at least 120 lp/mm resolution to get over all resolution of the combined sytem (optics+sensor) equal to 120 lp/mm. But this is not correct because total resolution (Rt) is given by following relation:
1/Rt^2 = 1/Ro^2 + 1/Rs^2, where Rt is total resolution of optics+sensor system, Ro is optics resoluiotn and Rs is that of sensor.
I am not able to comprehend this can anybody help me?
In other words I can put my doubt this way; what kind of resolution is required for the sensor to record all the information provieded from the lens?