Can anybody please advise me on the purchase of filters for black & white landscape photography, I'm relatively new to all this and unfortunately my budget doesn't extend to simply buying 4 or 5 and learning from my mistakes. I've been scanning through many entries for different tastes and it seems for the kind of Ansel Adams effect I'm seeking I should go for a B+W 023dark yellow(9)and a 090light red(25)? I have a 72mm lens with a good polarizer which seems to me will work well with both (not simultaneously, obviously!) - I'm really keen to get the sky very dark/black/graduated and yet want to keep the whites as good as brilliant. Will these filters give the right results? What about a lighter yellow, or the 091red?