As stated by another member, SFX without a red filter will look a lot like HP5+ or FP4+. The advantage is that the film is in that sense dual purpose and can be loaded in subdued light as it is extended red sensitivity not true infrared. However the downside is that, based admittedly on my one and only experience of using it, then unless the sky is included and even then it has to be a sunny day then a red filter makes little difference to the appearance of the picture i.e. compared to Kodak the white ghostly effect on foliage is hardly noticeable. The other ghostly effect provided by Kodak's lack of anti-halation backing is of course also missing.Originally Posted by jim appleyard
However in the right sunny conditions the effect is clearly infrared like, giving an effect which causes the print viewer to wonder whether it is brilliant sunlight or brilliant moonlight and creates that slightly ghostlike atmosphere which brilliant moonlight does .