Understanding depth of field and focus

If you get too close to your subject -- that is closer than your lens's minimum focusing…distance, -- then your lens won't be able to focus.…So, if you get up close, and you can't get focused -- your lens just searches back and forth, --…the first thing you need to do is start to back away.…Now, you can continue to try to auto focus as you pull the camera further from the subject,…but that kind of trial-and-error approach can take a while, because the camera is going…to keep focusing every time you try.…You might find it easier to employ a manual focus approach.…First thing I do is set my camera's focus to its closest focusing distance.…

Now, on this lens, I can actually turn the manual focusing ring without having to switch it…to manual focus. For other lenses, you have to make that change first.…So, what I do now is -- rather than trying to auto focus the camera to get it in focus; I'm…at my minimum focusing distance, -- I'm just going to move the camera back and forth until I get focus.…