I was thinking about buying a filter system. I have been looking at the Cokin P Series, holder etc, and some ND grads, and an ND filter. I presume the P series would be OK for lens sizes 52 to 77. I see the Kood ones going at a relatively cheap price compared to the Cokin, but I wonder whether they are worth buying. I can't afford to spend mega money on Lee filters as I have been rather extravagant lately with my new lenses. Any advice welcome please.