Yesterday I took delivery of a Konica AR to Fujifilm X adapter which I bought to allow me to use the 40mm f/1.8 lens I bought cheap a couple of weeks ago. I took a few test shots on my lunch break and it seems to perform pretty well (even without a hood) though the focus and aperture rings aren't as smooth in use as the best old manual lenses. It's sharp enough wide open, at least in the centre, though it suffers from mild blue and purple fringing in some cases and is excellent by f/2.8. There's no aperture click between f/1.8 and f/2.8, which is a shame. In the few examples I have the bokeh seems pretty good, especially considering it contains stalks and foliage which are often a torture test for bokeh.
With the small nature of the lens and that the AR mount's registration distance is around 5mm shorter than the K mount's, this combo could be the smallest I have for use on the Fujifilm, with the possible exception of the DA 40mm limited, though the Konica is 1 & 1/3 stops faster.
Wide open:
DSCF4273a by
Jonathan MacDonald, on Flickr
f/2.8
DSCF4264a by
Jonathan MacDonald, on Flickr
DSCF4274a by
Jonathan MacDonald, on Flickr