I really like the cokin P system to make filter use and changes easy. Much simpler than screwing a threaded round filter on and off between each shot. However, I tried stacking two "neutral" density filters together however and ended up with very bad pink color cast. Made the pictures unusable. I've read the same happens with the Z series as well. Too bad. Spent a lot of money and now the filters are useless to me. Would have saved money going with better filters from the beginning.