Home Forums Let’s Talk Photography Back Focus in the 50mm 1.2 and how to correct technique in order to prevent it Reply To: Back Focus in the 50mm 1.2 and how to correct technique in order to prevent it

#5466

Think of the plane of focus as an invisible wall, everything on the wall is in focus.  Depth of field is the area in front and behind the plane of focus that is sufficiently sharp to still be considered “in focus”.

 

I have a T2i.  The centre auto-focus point is more sensitive than the rest, so it is the only one I use.  I focus then recompose.  I have not noticed any problem with this method, from the camera as cause.  If you are using a lens at a distance that gives a very shallow depth of field, a problem that sometimes occurs is between focus and shutter release either the photographer moves forward or backward slightly, the subject moves forward or backward slightly, or both move in opposite directions.  This throws off the focus.  See page 69 of the manual, the page title is Shooting Tips.

One-Shot AF, AI Focus and AI Servo, all have their own ways of working.  AI Focus is slowest to operate, so if you know what you will be shooting, choosing One-Shot AF or AI Servo are better options.

 

My other bodies all have stronger auto-focus, so I use them differently.