I sometimes use 1970's era manual focus Pentax SLR lenses with my Fuji X-T2. I use an adapter to use these M42 mount lenses. It's just a fun thing to do. With my 54-year-old eye, manually focusing can be a challenge. I need a little assistance to determine if something is “correctly” in focus. I could use reading glasses, but I don't want to. It's just another thing to carry and probably lose. Fortunately, I don't have to. My Fuji X-T2 and most modern interchangeable lens cameras (ILC) have a feature call focus peaking to assist me during manual focusing.
Focus peaking is a focusing aid in live preview or electronic viewfinders on ILC that lays a white or coloured highlight on in-focus edges (contours) within an image using an edge detect filter. It highlights the areas that are in focus, so I can quickly focus the camera.
Something is bothering me. But I don't know what. I needed some fresh air. I took a very short walk, just 30 minutes, near my home. I didn't get far.