But you are still wrong . Blue filter on pan film naturally passes only blue, and thus "emulates" blue-only sensitive film, not an ortho film. Ortho film is sensitive to wavelengths from blue to green, so to emulate it with pan film, you need a filter that passes wavelengths from blue to green, and stops (absorbs) wavelengths from yellow to red -- that is a cyan filter.
Originally Posted by Michael R 1974
Blue filter would give a much more dramatic visual effect on BW image, especially with skin tones. It's definitely not "ortho" look, but more drastic. For ortho look, just go with cyan. You also lose less speed that with blue.