I acquired a set of B&W contrast filters and been running some tests. Here are the parameters: Test subject: landscape including blue sky, white cloud, trees, lawn, etc Film: Tmax400 Filter in use: None, Yellow, Orange, Red, Green Am I crazy in thinking, for landscape shots including sky and cloud, a yellow filter can basically be left on lens as default unless there is a reason to remove it? It enhanced the definition of cloud so much that the result is very pleasing to my eyes. Orange had little more effect but not as much as I expected, and Red even more. I was expecting pitch black sky with red - ala Ansil Adams but I didn't see it. He must use deeper red.... Fully knowing there is no such thing as "standard", is there such thing as "common practice?"