As was said before: most lenses will offer the option between manual focus or auto focus. Depending on what camera you shoot with, yo may be able to turn the auto focus off at the camera as well. Methinks you are asking because you may consider buying an older lens, which does not have the IQ of the newer lenses. Manual focus should be fine for macro photography; some shooters even have "focusing rails", a contraption that lets you set the focus on the lens, and then fine tune it with the rails. Rumor has it that the macro nuts are using those extensively. That said, it does become clear that one needs to have a good tripod to utilize this sort of thing. I have a Sigma 150, super sharp, and it can both auto focus or let me choose manual focus.