(A) Excerpt from Fujis manual for GW690 III, GSW690 III and GW670 III Professional cameras: (I quote Cleaning the lens As mentioned earlier, scratches on the lens surface can reduce its sharpness far more than you would think. If the contrast of your picture seems somehow insufficient and it doesnt look crisp enough, the cause is usually scratches on the lens surface. How to clean (1) First, blow off dust from the lens surface completely with an air blower. (2) Next, moisten a sheet of lens cleaning paper with plenty of Fuji lens cleaning fluid and wipe the lens gently with it in a circular motion. Always start from the center, then gradually move out to the edges. (3) Finally, after all contaminants have been removed, wipe off the remaining lens cleaning fluid with a dry sheet of lens cleaning paper. Again, start from the center in a circular motion, then move out to the edges. Caution: Breathing a mist on the lens surface then wiping it off with silicon cloth or other similar material is the worst thing you can do. Never do it because this is one of the main causes of scratches on camera lenses. (End of quote) (B) Now to the Cleaning your filters instructions in the Hoya Filter Catalog: (I quote Due to their high precision, filters should always be handled with care and kept clean whenever possible. Filters should be cleaned gently with just a lens tissue or soft cotton cloth, such as Hoyas Hi-Tech Microfibre cleaning cloth. Never use any chemicals, such as lens-cleaning fluid, on your filters, as these can damage the coatings. If any stubborn stains occur, these can usually be washed off with some clean water and a soft cotton cloth. (End of quote) Now, why so completely different cleaning instructions for modern lenses and filters? Can anyone tell me? I am curious to know.