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Nikon NIKKOR Z 24-70mm f/4 S

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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Diglloyd Guide to Mirrorless offers comprehensive integrated coverage of most APS-C and full frame mirrorless cameras and lenses.

Special emphasis is placed on Sony full-frame, including Sony lenses and the high performance Zeiss Batis and Zeiss Loxia lenses plus Rokinon/Samyang and others. Fujifilm X, Olympus and Panasonic M4/3, Sigma dp Merrill and dp/sd Quattro are also covered in depth. Years in the making, it offers a wealth of material for choosing and using a mirrorless camera.

  • Make better images by learning how to get the best results right away. For example, the best way to set up your Sony camera.
  • Save money by choosing the right lens for your needs the first time, particularly with the numerous lenses available for Sony.
  • Make better images, a sort of “cheat sheet” saving yourself months or years of ad-hoc learning—best practices and how-to and processing parameters are discussed and shown.
  • Jaw-dropping image quality found nowhere else utilizing Retina-grade images up to 28 megapixels filling up to 5K display, plus large crops.
  • Real world examples with insights found nowhere else. Make sharper images just by understanding lens behavior you won’t read about elsewhere.
  • Aperture series from wide open through stopped down, showing the full range of lens performance and bokeh.
  • Optical quality analysis of field curvature, focus shift, sharpness, flare, distortion, and performance in the field.

Want a preview? Click on any page below to see an excerpt as well as extensive blog coverage, for example on Sony.

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