I read some info about the 51 point AF system for the new Nikon D300.\nThe dpreview showed a graphical presentation on the locations of those\n51 points within the targeted digital frame (approximately covers 2/3\nof the square, centered in the middle of the frame). Could someone\nprovide a little more detail about this 51 point system?. I may be a\nlittle confused about this concept against the exposure metering in\nsome old digital cameras.... averaging or spot metering. I guess that\nthis is not about the light exposures, but instead it is about the\ndistance measurements from the object(s) to the sensor plate. If the\nlater is correct, then how do they manage to get a razor sharp picture\nif you have to average the distances over 51 spot locations? Or, did\nthe camera actually take average distances from those 51 locations? I\nguess you cannot have 51 different focused distances to the sensor and\neach measured distance will be registered into a single 2D plate, can\nyou? Or, I may miss something completely and more fundamental here? I\nthink that taking average distances over 51 points will not definitely\nwork to produce a razor sharp image on the main focus/target area,\nunless each of those 51 points have identical distances (or close to\nidentical distances) to the sensor.\nThanks for discussion and comments.