I want to get some gradual ND filters for outdoor shots on my D80 with the 18-200. I also want to add a UV and circular polarizer. How does one do this best?Get a regular 72mm UV and a 72 mm polarizer and a cokin set?Get a regular 72mm UV and a cokin set + cokin polarizer?Also, which cokin kit filters would work at the wide angle end, or do I need adapters? thanks!