Tiffen IR ND 2.1 (filters range from ND 0.3 and up) appears to cut more magenta, which works well with the BMCC, compared to some of the other filter brands, and the Tiffen may be more cost effective for some users, compared to, say, the Formatt, which is also very good IR cut match for the BMCC and many other cameras. As a side note, I am not sure if the BMCC not having an OLPF allows more potential IR contamination, or if IR relates to this particular sensor design. Personally, I am glad there is no OLPF, other than potential moire issues that can not being controlled or detected when shooting in some instances. You may have seen some 5D users, even a Red user, have removed the OLPF to reap other benefits, which I think is part of what makes the BMCC footage so remarkable.
I am probably OT now, so in ending, may I ask you, John Brawley, with your extensive use of the BMCC in a production environment, what IR filter do you use, or found to be a good match for the BMCC? And if not too OT, what is your preference with regard to having, or not having, an OLPF on the BMCC? Thanks.