Although you get to use all sorts of lenses on the Fujifilm X series camera body, however you will lose the ability to perform auto focus (well, of course) and one will need to rely on manual focus in order to get things done. It may sounds hard and troublesome, but actually it is pretty easy to be done as there are features such as focus peaking, digital split screen and magnification available on the Camera body which assist you in obtaining focus accurately.
Of all the manual focus aid, my preference is to use focus peaking. Generally speaking, focus peaking will show colour dot over the edge of your subject when it is in focus. This method holds true for most of the time. However, when you are shooting high contrast object, the edge will sometimes be fooled to show it is in focus with the peaking dot while in actual the subject is not yet in focus.
To work around this limitation, I find that instead of looking for the edge to show peaking dots, look for the depth of field. When you focus, you should be able to see peaking on certain distance/area/zone, that’s your depth of field/region where with your given setting, the subject falls within that region will be in focus. So you just turn the focus ring until that region covers your subject. By focusing this way, I found that my success rate is much higher.
When required, I’ll couple focus peaking with magnification to get the most precise focus. As for digital split image, I personally don’t find it useful for me to acquire focus easily. Hope this sharing will become useful for you.