Specific circumstances are out of questions. If you remember, about 5 years ago I lost my 17-35 to flash of sea water, there was yacht's competition. I've posted images of that. I've lost my first 16-35 to drunk idiot in Germany, who without any provocations from my side, my D3 was on my shoulder, splashed a shot of strong alcohol on the lens. So on and on, say me that. On the other hand, under some light, I've admitted some a hair, maybe two,improving of sharpness due to cutting UV by filter. In most usual cases good, pro quality filter behaving neutral. It is absolutely true, by member's post in another topic, I am doing my living by images. I have no rights to make mistakes, very costly otherwise, believe me. Dimitri.