I am so inspired by some of the IR work I've seen here, and now comes the inevitable searching for a filter. I do realize the camera being used makes a difference, as well as processing afterwards. However, I really like the images I've seen from the Hoya R72. Is this the same as the RM72? I've noticed the RM72 for 77mm thread is somewhat expensive. More so than the Tiffen 87. But I haven't seen anyone using the 87. Does anyone have experience with this filter? What are your favorites and why?