Imagery: Auto - Large Table of Contents

EXCERPT page containing first few paragraphs. 2021-11-29 14:01:25

Nikon NIKKOR Z 24-70mm f/4 S
Nikon Z7

Autofocus Accuracy: Zone of Focus Error, Example and Mitigation

This page shows just how wildly inaccurate the placement of the zone of focus can be with the Nikon Z7 (and other systems!). Placement of the zone of focus has major implications for total sharpness and visual impact, yet autofocus can easily choose a sub-optimal choice of focus which displaces/biases the zone forward or rearward even as the chosen point is fully sharp.

A discussion of how to manage this challenge follows the example.

Zone of (sharp) focus = near to far depth through which focus is sharp. The depth of the zone of focus depends on focal length, distance, and aperture. What is “sharp” should be taken to mean “sharp enough” by whatever criteria one has but for autofocus it means whatever the camera autofocus would determine to be in focus (which could get sloppy in dim light). The point is there exists a zone of sharpness of some depth; it could be 1mm, 1 meter, 10 meters.

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