Recently Nikon issued a new firmware release (1.0.2). In the list of changes improved subject tracking performance for AF-C is mentioned. On dpreview forums, several people mention also improved AF-S performance. As usual on those forums, such statements create a lot of fuzz because of claims made without any backup. Time for a small experiment
Reikan’s Focal Calibration Tool can be used to check focus consistency of a camera-lens combination. The tool allows to use any target at wish. WIth many targets (e.g. Reikan’s own target, Tom Hogan’s target, ISO target, a simple line etc.) the consistency of focus reaches figure that are > 96% using my D800 and email@example.com.
When I use a specific book as a target, the consistency drops to 92-93% (repeating tests). After performing a firmware update on the tripod, and under the exact same circumstances, the consistency increases to 97-98%.
Typical results FW 1.0.1:
Typical results FW 1.0.2 (scale is different):
Impression of what the central AF point sees as a target:
This gives a very strong indication that AF-S consistency has been improved with this firmware update. Further tests will follow.