The lens is rangefinder coupled:
The idea is to frame with the external finder and focus with the cameras internal rangefinder.
However as the depth of field is large, and frequently the focus distance is set to fall within the depth of field marks encompassing your subjects closest and furthest distance, you may not use the internal rangefinder very often.
It's the weird colour scheme that freaks me. Every time you try to operate one of these weird black controls, which are labeled in black on a black background, a small black light lights up black to let you know you've done it.