Hi Anton<
your misstaking "frame-rate" with "shutter speed". If you film standar PAL you allways get 25 images per second (25 frames or 50 fields that is the same in the interlaced world). To make a clean slow-motion you need to set the "Shuter speed' of your camara at a higher speed of the normal 50fps. You get the same nunber of images per second, but these images have less movement-blur. Is the same than when you rise the speed in a normal foto-camara. So don't look for nothing in FC. Look for the "shutter" in your camara.
Cheers,
Rafael