This a theoretical question. Using a fast lens at say f1.4 in full sunlight requires a high shutter speed, so if you run out of a high enough shutter speed you then use a ND filter to reduce the light. Now I'm not talking about the quality of such filters but does having a filter reduce the sharpness of the image as a ND filter obviously reduces the light by blocking some of it hence you are not getting all the light reflected from the scene. Is the reduction so small so as to be negligible or with stronger filters affecting it more?