Focusing works the same way on fixed and zoom lenses.
Manually focusing an SLR (single lens reflex) lens is an art form, one that has been largely replaced by electronic auto focusing. It's important to know manually focus a lens, however, in case your autofocus stops working or to simply help develop your photographer's eye. You should notice a thin rotating ring on your lens. This is the focusing ring. Turning it one way focuses far away; turning it the other focuses it closer. Which direction you rotate to focus differs by the brand.
Some point-and-shoot cameras allow manual focus adjustment as well.
Instructions
Focusing an SLR Camera
1. If shooting the end of the guitar, first focus beyond it.
Practice on a nearby subject. Try to use a static object, as people move around. Rotate the ring until the subject is in focus, and keep rotating until it is slightly soft.
2. Rotate the ring in the opposite direction so you can see the subject clearly, and once again keep rotating a little bit so the subject is slightly soft.
3. Now come back so you can clearly see where to focus.
Rotate the ring back so your subject is nice and sharp. The back-and-forth focusing helps you see where to best focus on your subject.
4. SLR lenses have an "infinity" focus setting that is typically used for landscape photography. It makes a far-off object or horizon line in sharp focus while the foreground is slightly softer. Turn your focusing ring all the way to its farthest focusing distance to achieve this.
Focusing a Point-and-Shoot Camera
5. Set your point-and-shoot camera to it's "manual focus" setting, which is usually found under the camera settings menu.
6. Adjust your focus manually. There are usually "Plus" and "Minus" buttons on the camera. Press "Plus" to focus on far-away subjects and "Minus" to focus on near subjects. Some point-and-shoot cameras have a dial you spin to change the focus instead of buttons.
7. Press the shutter button when your subject is in the desired focus.
Tags: Rotate ring, your subject, focus setting, focusing ring, keep rotating