I too would like to know what canon means by "F". Since your shooting 1080i 24f, i would assume they just use f as short for fps, as in your shooting 48i 1080, which is technically 24fps interlaced. If your shooting at 24fps, and i assume you plan on getting your film telecined, which means it will get a pulldown (unless otherwise requested), then you will be editing with 29.97i footage, so yes, your mixer should be recording at 29.97, or as they call it, NTSC dropframe. However if your editing at 24fps and plan to do a pulldown at the end, then i cant honestly give you advice because i dont understand how the 'framerate' of audio works. I wouldnt reccommend letting telecine apply pulldown and then you removing it, your just throwing away resolution for no reason. If you plan on doing any rotoscoping, always work in progressive.