Manual Focusing with Live View

Auto-focus is an amazing technology.  Except when it's not.  When the existing light is dim, or when there's an object you want to be tack sharp but it's too small for the auto-focus to latch onto, then auto-focus can be very frustrating.  Sometimes, auto-focus just doesn't nail it for some reason, especially when the focus point is off-center and not under one of your cross-type focus points.  At times like these, manual focus can be the way to go.  Don't get put off by that!  The technology is amazing, but it's not going to perform miracles.  You, on the other hand, can.  People were shooting Pulitzer Prize winning photographs long before cameras knew how to focus themselves.

Modern DSLRs usually lack the manual focusing tools common to older cameras, such as split screens and microprisms.  But one thing modern DSLRs do have is Live View mode, which in my opinion is even better.  Basically, with Live View mode you can use the camera's big LCD screen to zoom in really tight on the focus area, then manually focus the lens before taking your picture.  Using this method, you can forgo the vagaries of auto-focus and achieve tack-sharp focus every time.  In fact, if you do it a lot, you'll be more reliable at nailing the focus than the auto-focus system.

Here's how it's done:

• The best time to use Live View manual focus is when you have the luxury of taking your time setting up the shot and getting everything just right.  So it's ideal for landscapes, posed portraits, still lifes, etc.  I think it works best with a tripod because it's hard to hold a camera still when you're holding it out in front of you to view the LCD (despite the fact that that's exactly the way point and shoot cameras are designed to be used nowadays).
• Remember that the LCD screen on your camera does not have a diopter adjustment, so you must wear your reading glasses if you're far-sighted!
• Put the camera and/or the lens in manual focus mode.
• Turn on Live View mode.
• Now, move the focus area indicator to the part of the scene you want to focus on and zoom all the way in.  On a Nikon, you move the focus area indicator using the multi-selector arrow button thingy and you zoom in and out using the zoom + and - buttons.
• If the Live View display is too dark, use a large aperture to do your focusing.  Then stop it back down to your desired aperture before actually taking the shot.  Why? When you use the viewfinder, the lens is opened all the way until you click the shutter button at which point the lens stops down to your selected aperture and the picture is taken.  By keeping the aperture open, the camera gives you and the auto-focus system a nice bright view to work with.  In Live View, however, the aperture is always set to whatever you've dialed it to even before you click the shutter button.  So if you've dialed up a small aperture, Live View will look dim.  So open up the lens, focus the camera, then stop it down before you take the photo.
• To focus, rock the focus ring on the lens back and forth until you find the best focus. 
• Then take the photo.  Easy peasy.

Unfortunately, the inexpensive lenses that I use often have very short throws on the focus ring.  This helps speed up the auto-focus system but it makes manual focusing touchy -- the focus can change a lot with the slightest rotation of the focus ring.  But it's still doable even on my most hair-triggered lens (the Nikon 55-300mm).

If you do this a lot you'll get really proficient at it.  And you may come to rely on it when your focus absolutely, positively must be right.