AF-ON on D600 ... hit and miss. Me or the camera?

Menu a3 (focus tracking with lock-on) determines how large a delay there will be before the camera AF system reacts to a change in subject distance in AF-C mode. This can cause focus errors as AF-C will not "keep-up" as the subject moves closer/father from you or you move closer/farther to the subject.  It's designed  for tripod situations where people walk between the camera and the subject when AF-C is being used. In those situation..."focus tracking with lock-on" will prevent momentary loss of focus lock when someone briefly gets in the way. In hand held situations it can slow the responsiveness of AF-C and is often a cause of lower in-focus keeper rates, particularly during fast action shoots. Setting menu a3 to "off" for all put a very specific situation....usually results in keeper rates going up.

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)