The above video shows how the X vario deals with manual focusing. There is a large focusing ring nearest the camera, which by turning it unlocks it from the position where its set for AF. As soon as the ring is moved the square appears in the centre of the screen and you can see the image snap into focus. Its quick and its accurate, but does of course rely on communication between the lens and camera. Not possible, as far as I know, with 3rd. party lenses on mirrorless cameras.
The other system I like is the Nikon white dot. This is left and right arrows on the bottom of the screen which move until the centre of the image is in focus. Then a small white dot appears. This is very accurate, reasonably quick and works on the Voigtlander MF lenses I used.
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