X-Fujinon lenses use the Fuji Photo Film Co. X Bayonet mount, not to be confused with the new Fujifilm XM Mount for their mirrorless digital cameras.
This lens, the 50mm f1.9, had to have been the standard kit lens for the Fuji line of lightweight (plastic) SLR cameras. There is one cheaper, the 55mm f2.2, which can be found with both the earlier M42 mount, as well as the X Bayonet mount.
Overall, the mechanical quality of the lens seem very low. Except for the lens mount itself, and the aperture, everything else appears to be made with plastic, including the focusing coils. Focus is very loose on this particular lens. The glass seems to good, and overall contrast is good.
Wide open, this lens provides some ‘glow’ on highlights, but stopped down to f5.6, sharpness is good in the center, somewhat fuzzy nearer the corners, even on an APS-C sensor camera like the Fujifilm X-E1. The aperture has 5 fairly straight blades, so I expect a nice 10 pint starburst, but have not had the chance to test that yet.
A few shots wide open. Bokeh for highlights, leaves some interesting balls, with a little bubble outline. Smoother backgrounds are ok, but nothing interesting, and a little noisy for my preferences.
Details/sharpness when wide open is not great, even in the middle of the field. Look at the columns in the front porch, and you can see there is a glow on the brightest highlights.
Stopping down to f5.6, and details look great in the middle of the field. Going out to the edges, and you can see some distortion.