used my 1st roll of SFX with a true Infa red filter last week. Not sure of the exposure so set meter on 12 ISO and opened up 1/2 stop for a total of 3 exposures. Didn't need to the basic exposure was right every time. Not as effective as good old HE Infra red by Kodak (RIP) but a cheaper alternative. Once I have used the SFX I will try the Rollei branded IR film sold by one or two of the specialist shops.