Hi guys. I recently bought a 15-85 lens as a walkabout, but also to get into landscapes. I want to get a filter holder and maybe 2 or 3 filters. Can anyone suggest what would suit best please. Are Cokin any good, or would I have to get something more expensive? Seeing that the lens is 77mm, what size of filter set-up would I need to avoid vignetting? Will 85mm be enough, or would I need 100mm? Any recommendations of brands? Finally, which 2 or 3 filters would be most beneficial/useful for landscape shots. Any advice would be gratefully received as I haven't really got a clue.