My first set of ND Grads , the Cokin Z-Pro three filter kit, arrived today with the holder. The filters are designated 121 L M and S.

Are there any tips from others on the use of these, such as things to look out for?

I am aware of the colour cast issue for example and am wondering if this is correctable?

I will have a play with these for a while and think about adding to these incrementally.