According to Ilford's website SFX 200 film has extended red sensitivity to 740 nm. Maco Cube 400 goes to 730. J&C Classic 200 and 400 are advertised to have a range to 720 nm and are classified as superpanchromatic emulsions. Has anyone comparison tested using dark red filtration? I wonder how much difference there actually is between 720 and 740 and if 740 is really approaching infrared. Maco IR goes to 820 nm and Kodak HIE to about 920 nm. I know they are true infrared emulsions.