You are not mandated to use a red filter with this film. If you don't, you might as well use a regular film.... If you use the hassy red filter, it will exentuate blue sky a lot darker (like any Pan film does!) and it might yield a very mild IR effect on foliage (YMMV).... You need to use a proper IR filter on it to filter out all other wavelengths except the IR range to get the full IR effect.