Years ago a cinematographer friend told me of a dinner he once had in Paris with a Mr Cooke. Mr Cooke of the famed British optical firm Cooke, Taylor and Hobson.
During the meal Mr Cooke explained that he spent most of his waking and working hours designing lenses to perform with maximum sharpness and minimum degrees of aberration to achieve the perfect capture of the photographic image. In spite of these heroic efforts he spoke with some level of bitterness that certain cinematographers persisted in covering his carefully crafted lenses with all sorts of rubbish, grease and diffusers to degrade, soften and generally muck up the performance of these precisely manufactured optics