You asked
Is the fujifilm xf 18mm f 2 r sharp wide open?
I don't have a sharpness test for the XF 18mm f/2 R at f/2, so I can't give you a verdict. The Fujifilm XF 18mm f/2 R page covers its specs: it's one of the three original X-mount primes, small and light, and on APS-C it frames like a 27mm on full frame. f/2 gives roughly the depth of field of f/3 there. It's not stabilised, and it fits a long list of Fujifilm X bodies.
If you want to judge wide-open performance yourself, shoot a test at f/2 and check the corners of the frame at 100% in your editor. For a wider option the site describes as sharp and low-distortion, look at the Fujifilm XF 14mm f/2.8 R. For the APS-C versus full-frame question, see sensor sizes.
Written by Claude from this site's pages.