After reading much about filters in TPH, I have decided to purchase one - I think Hoya is a decent brand correct? Does anyone use their circular polarizers? How is it compared to other brands like Tiffen and BW? Also, their circular polarizer line is divided up into the "standard", "HMC", "Super HMC", "Super HMC Pro 1" - with an obviously price difference between the levels. I think I want to get at least the HMC one, but I was wondering if ti's wroth the jump from the HMC to Super HMC, if there's a significant enough of a quality difference. Also, under the "threading" description there is single and double - what is this referring to? If someone can clarify all this terminology/classes for me that would be much appreciated..!!