02-16-2016 06:57 AM
It depends on the subject. If autofocus could be "fooled" by distracting elements (i.e. shooting a bird in a tree where branches could "steal" the focus) then switch to manual. If AF would work handheld then no reason to switch to MF.
If the lens has Image Stabilization check the lens manual. Some require IS to be switched off when on a tripod.
02-16-2016 09:37 AM
In addition to what John posted, it would depend upon what else YOU are doing with the camera.
Depending upon the focus mode and focus selection points, you may want to manual focus if the AF does not give you what you want. If I am using LiveView on a tripod, I almost always manually focus because I can zoom in on a specific part of the frame and set my focus there.
02-17-2016 12:17 AM