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EXCERPT page containing first few paragraphs. 2021-12-04 14:03:11

Focusing Tips

This page is provided both for general background information on the need for accurate focusing, as well as to provide actionable tips on how to reliably achieve sharp focus. It is a general discussion not aimed at any particular camera brand or lens.

For examples of focus error issues, please see Focus Accuracy at

Some photographers still believe that focusing by the distance scale on the lens is sufficient to extract top results if one simply stops down to f/8 or f/11. Experienced digital shooters know that such an approach is inadequate with today’s 10+ megapixel cameras (or even 4-megapixel cameras, to a reduced degree). Stopping down to f/8 from f/2 delivers 4X the depth of field (in theory). If the depth of field is 1 foot at f/2, then it’s only 4 feet at f/8, and with real lenses theoretical and actual depth of field are two different animals. Depth of field does not mean that contrast remains uniform throughout that zone, or that aberrations are all controlled (though stopping down reduces some optical aberrations).

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Diglloyd DAP is DSLR-oriented, but also contains workflow and other topics. Much of the focus is on Canon and Nikon but also Pentax and Pentax medium format.

Special emphasis is placed on lens evaluation, focusing on Canon and Nikon and Sigma lenses, but with a few others like Rokinon/Samyang.

  • Make better images by learning how to get the best results right away.
  • Save money by choosing the right lens for your needs the first time, particularly some of the new Sigma Art lenses vs Nikon and Canon.
  • Workflow discusses image organization, raw conversion and post processing. Many examples show processing parameters for direct insight into how the image was converted.
  • Jaw-dropping image quality found nowhere else utilizing Retina-grade images up to full camera resolution, plus large crops [past 2 years or so].
  • 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 Nikon or on Canon or on Pentax.

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