So I want to do some IR shooting using the new Maco IR film in my Nikon, and so need a suitable infrared filter. Given that you apparently need a pretty heavy filter to get good IR effect with the film, but also that I want to shoot handheld with my 50/1.2, I need to find the darkest IR-appropriate filter that isn't completely opaque. I can't tell from specs I've seen anywhere if the RM72 is just really dark or if it is actually opaque. Anyone have one of these that can tell me for sure? Thanks.