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Message: <blockquote data-quote="spb_stan" data-source="post: 634250" data-attributes="member: 43545">When using a slow lens, one that has a maximum aperture that is small, such as the f/6.3, AF performance will be degraded when using any but the center focus point. So tracking will be unreliable further from the center because that center AF point is the most sensitive one. Using slow lenses requires tracking moving object by panning to keep the center point on the subject. Sometimes, in good light it will work using outer focus points but it will not be consistent. That is one of the benefits of fast lenses, with wide maximum apertures, because even when stopped done to, say f/8, the metering and focusing it done before the aperture is closed down for the exposure. That f/2.8 fast zoom meters and focuses at that wide open f/2.8 and the instant you click the shutter, the aperture closes down to the exposure aperture. The 51 point and 11 point tracking have different processing times so the 51 point should be used when slower moving subjects are needed to be tracked over a wider portion of the AF sensor. The 11 point tracking is best for fast moving erratic movement because fewer focal points are being evaluated so the AF processor can update faster. For sports where you pan with the movement, the 11 point will be better. The tracking does not show the FP on the monitor because the starting point is the only one the camera knows about, until the subject moves out from under the selected point. If it showed you every transition point, you could not pan or track with FPs lighting up randomly, quickly on the VF. The last thing you need with following action is too much data to distract you. It does not help you to know the FP shifted 3 times in 1/10 of a second between press of the AF-On button and shutter release.</blockquote>

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