There is no crop factor on Fujifilm XF lenses, because these lenses have been designed for X-Mount and APS-C. So they are perfectly "full-frame". You'd have to adapt XF lenses to MFT cameras (or smaller) in order to achieve any crop. The new Hasselblad lenses for the new Hasselblad medium format camera are full-frame, too, as they are specifically designed for the 44x33mm sensor inside this camera. However, adapting Hasselblad H series lenses on this camera will result in a crop factor, because the H series covers a larger image circle.
So crop factors become relevant in systems that support more than one sensor size (like the mentioned Hasselblads, pretty much all legacy (D)SLR systems, but also Sony's new mirrorless system that features a mount that's used for APS-C and 24x36mm sensors).
When you adapt a lens that was made for 24x36 film on APS-C, you only use a cropped portion of the actual image circle, so there is a crop factor to describe that portion and the resulting image impression based on the larger (aka full-frame, uncropped) image circle. That's why we have focal reducers like Speed Booster Ultra or Lens Turbo II, which let us use 24x36mm lenses on APS-C in a way like they would perform on a full-frame camera (and with one stop of additional brightness, hence the Speed Booster name).
Referring to "full-frame" as a synonym to 24x36mm cameras is basically a lazy relict of the past, based on the fact that many legacy users only know and used that format. That's why they use it as a reference point for everything, which results in crazy stuff like "crop factors" below 1 for medium format lenses. All this will probably vanish when the current regime of "old farts" will be replaced by the "smartphone generation" who couldn't care less about such relicts.
Alright, I know it's not the gentlemans way to write a reply on ones own topic/question but I found the solution to my own problem. It seems that I was misguided by the clickywheel.
So here is the answer if anyone else wants to know:
Just press the DISP/BACK button!
Yep, too easy. Who would've thought. Sorry for wasting your time.
