Tutorial on focus

[dbergendorf]

My T3I won't focus. (One thing I know is that I can only take snapshots of a single person. It will try to focus between two or more people, then both are fuzzy.) I know I've got something set wrong, but I can't figure out what. Where can I find a tutorial on how to focus on more than one subject in the dead center of the scene? 

[Waddizzle]

When you take a picture the camera can only focus on one point, no matter how many auto focus points might light up.  When the camera is in one of the automatic modes multiple can AF points light up.  When this happens the camera is showing you potential AF points that are momentarily in focus.  When you press the shutter, it will select one of the focused AF points, usually the closest one to the camera.

To force the camera to focus on what you want, manually select the center focus point, and put the camera into "One Shot" mode.  Avoid using the "AI Servo" modes, not unless you're photographing fast moving subjects, like sports or wildlife.

[ebiggs1]

"My T3I won't focus."

The thing to do is set your T3i to the green square or P mode.  The lens to AF. Go out side on a bright day and see if it works properly.  If it does there isn't anything wrong with the camera and you do have something set wrong.

So now go into the menu under tools and clear all settings including personal settings.  In other words set it back to factory default setting.

The best by far is to use just the center focus point.  Don't use AI-Servo until you are well advanced, if ever.  It is not a user friendly setting.  Also, remember the T3i will not fire if it can't achieve focus unless in manual mode. A dim room inside may cause that to happen.

[TTMartin]

---

@dbergendorf wrote:

My T3I won't focus. (One thing I know is that I can only take snapshots of a single person. It will try to focus between two or more people, then both are fuzzy.) I know I've got something set wrong, but I can't figure out what. Where can I find a tutorial on how to focus on more than one subject in the dead center of the scene? 

---

Your question is how to increase your depth of field, how much is in focus, rather than where to focus.

The higher the f/number the smaller the aperture the larger the depth of field.

The wider the lens, the larger the depth of field.

The further you are from your subject the larger the depth of field.

It is a combination of these three things that determines how much of your photo is 'acceptably sharp'

Try using f/8 when you are photographing more than one person.