Have noticed quite some debates on whether use a UV filters in the discussion forums recently and at the past. Both have their points but just one thing concerns me that might related to the decision on using a protective filters – When dust or pine pollen got stuck in your front element, especially those with some moist, they cannot be easily blow off. How can you clean them? All of my L lenses have protective filters but I have bad experience with my video camera’s lens. I tried different types of cloth or liquid form solution, after removed the dusts but I can still notice marks left in the lens (more obvious if see it under direct sun light). I guess this is same experience as people leaving finger print in some special coating glass element such as anti-glare glasses, expensive watch with anti-glare sapphire crystal, etc. Very difficult to clean / clear the finger print. So my concern is whether the cleaning process of the camera lens’ front element actually hurting the coating?