*And* the compensation varies with the time of day, because the ratio of IR to visible changes (highest in late afternoon, lowest at high noon, generally). I never understood why so many people insisted that you needed to use EI 3 or less for IR film when I was getting decent shots at 6 or 12---well, I was doing all my shooting after getting home from work, when the visible light was dim and the IR relatively high. I suppose there could be variance with altitude too. Cripes, why doesn't anyone make an IR light meter?Another problem is that the IR light reflected varies based on the vegitation. Deciduous trees and lawn grass reflect the most, and conifers and shrubs vary. Once again, Kodak had the best, and it's never been matched. Your results will vary, and will be useless without the right filter.
I've never tried it, but I remember reading that it only worked with HIE and was similar in transmission to one of the far-IR filters. The Rollei film doesn't go very far out of the visible range, IIRC.Oh, yeah: the tail end (black part) of E6 can be used as an IR filter. I've done it with Kodak, but I never tried it with the others. It might work. If you have some lying around, go ahead and try it, but you may need long exposure times.