I am considering purchasing this lens. The best price I can find is $1,435. I want to get at least a UV filter to protect it from my fast moving 2-year old, but what advice would you have for brand or quality? What other filters would you recommend? I've read that a circular polarizer is what I need for outdoors and that square slide-in graduated ND filters work best so you can adjust them as needed. Sorry for so many questions but your answers are highly valued. Thanks