EOS 7D AF- Centre point 'increased sensitivity' with fast lenses

[insanitybeard]

With the EOS 7D, all 19 AF points are cross type, but the blurb states that:

"for enhanced precision, the central AF point features extra sensitivity when used with lenses having a maximum aperture of f2.8 or faster" (taken from Canon's official EOS 7D brochure)

Does this mean the centre AF point is double cross type or have an additional horizontal / vertical line activated at f2.8? Or is it just a more sensitive standard cross type sensor? I can't find anything in Canon's literature or in the likes of dp review that clarifies it.

Thanks!

 

[Loswr]

Does this mean the centre AF point is double cross type or have an additional horizontal / vertical line activated at f2.8? Or is it just a more sensitive standard cross type sensor? I can't find anything in Canon's literature or in the likes of dp review that clarifies it.

The center point on the 7D is a dual cross point, an f/5.6 cross in a '+' orientation with an f/2.8 cross superimposed in a 'x' orientation.

http://www.the-digital-picture.com/Photography-Tips/Canon-EOS-DSLR-Autofocus-Explained.aspx

 

[insanitybeard]

Thanks Neuro! I knew you'd clear that one up!