I have a 503CW and an 80mm lens and a 150mm lens right now. I want to get some filters that will fit both lenses so I need a system that will allow me to buy just one filter for both lenses, not 2 different sizes. My questions are: what brand of filters do you recommend? What is the largest size I need if I am also thinking of getting a larger lens like a 350mm? And last question... what parts do I need to put all this together? I have heard Cokin, Hoya, and others.