I read somewhere that filters that contained Didymium, among other things had a noticable effect in enhancing reds and yellows. Is this the case, and does anyone have any personal experience with using filters like these? Would using them on Velvia fall scenes be overkill?
Yeah they work. Very good for fall colors. I use a cokin -P sized and a Marumi redhancer. However, avoid white objects like clouds as they tend to get a strong magenta cast.