One of the reasons I changed to an auto-focus camera was because my eyes were getting too old to focus
quickly 
I still have to use manual focus with some macro subjects where the camera wants to focus on the background rather than the subject and occasionally, such as my 'November Fungi' photo in my gallery, the light is too low for the auto focus to work but in these situations the camera still stops down the aperture at the moment of exposure - it's a long time since I used a totally manual 'pre-set' lens!