Lu aujourd'hui sur Imaging Resource, lien dans un post ci-dessus

"Autofocus. Still in a 9-point diamond array, the EOS 40D's f/5.6 AF points are all cross-type, meaning that they're all sensitive to both vertical and horizontal lines. Nestled in the center is an additional precision AF sensor that I'm going to call X-Type. This sensor is arrayed diagonally and comes into play when you mount a lens of f/2.8 or faster. It has the advantage of detecting both horizontal and vertical lines, adding another dimension to the overall capability of the AF array."

Le colimateur central serait exploitable en croix (+) dans tous les cas mais pour pouvoir l'exploiter en croix (X) oblique il faut une optique 2.8 ou mieux (1.8 ?)

Jacques Dusat