Steve: I'll skip right to question 3! SFX is ok, but in my opinion it is not worth it. If you are after some extended IR sensitivity, move right to Kodak HIE IR film. I use it extensively for studio portraiture. HIE: 1. Rated 320, with No filter! 2. Processed in D76 stock 11min @68F. 3. Print using 'considerable' magenta, plus 'some' yellow filtration. And employ 'some' enlarger softening/diffusion. The printing is ofcourse subjective. But can yield superb portrait images.(posted 9345 days ago)Mike