Not sure if this is the right place to post this thread but i am sure an administrator will correct me if i am wrong.
I would like to purchase ND grad filters for landscape shots. What are the essentials, i have seen a post somewhere that stated a 'P' type would be the correct choice for a 17-40L on a 20d- if i were to upgrade my body to a full frame would it make a difference to my filters, i dont want to have to replace filters as they appear to be expensive.
I know you have to have a screw in mount, an adaptor and then the lens?
Also what would you recommend to start with in terms of filters- or does anyone know of a filter kit that cokin make? I like the idea of slide in filters as it offers that chance to try out some new crazy effects. Anyone out there have experience with this type of filter, if so i would like your advice please. Dont be afraid to go into too much detail as i know nothing abot this area.
I would like to know what you keep your lenses in as i here the slide in filters scratch easily, and i would also like to know what type of filter you went for, i think there are 4 types of cokin filter series- so answers on a postcard, thanks for respons in advance.

? does anyone have a bad opinion about cokin adaptor and holder- or is it just the glass that they are poor on lol 

