SHUTTER-BUTTON AF
The default setting on cameras is to have autofocus initiated by your first touch of the shutter button.That makes sense, and it works really effectively – except when it doesn’t. Three quick remedies: aim the AF point at the subject first, half-press the shutter button to focus, and recompose before shooting; use the AF-L (autofocus lock) button to hold focus, then shoot; or move the AF point to rest over the subject, focus and shoot.