You can try Kodak HIE if it's available there. Ilford SFX is not a true infrared film - it is sensitive only upto 740nm. Kodak's HIE is sensitive to 900nm. You will get good results with a #25A red filter. If you use an opaque infrared filter like an 89A, 87 or 87C, then you'll be capturing only infrared wavelengths.(posted 8979 days ago)You can focus through the red filter, but if you are using the opaque filters you will need to prefocus, meter the scene, put on the filter and then take the shot. More details at Kodak's web page.