You asked
Is the voigtl nder nokton 50mm f 1 2 aspherical hard to focus manually?
The site doesn't rate how hard this lens is to focus by hand. What it does say is that the Voigtländer Nokton 50mm f/1.2 Aspherical has no autofocus, so every shot is focused by you.
At f/1.2 the depth of field is very thin, so a small focusing error can leave the eyes soft. Take your time, focus on the eyes, and check the frame on the screen or in the viewfinder before you press the shutter.
If you're new to manual focus, lenses explains where a fast prime fits in a first kit. Its own advice is to start with a standard zoom and add a fast 50mm once you know what you shoot.
Written by Claude from this site's pages.