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EXCERPT page containing first few paragraphs. 2022-07-06 10:04:09

Sigma 20mm f/1.4 DG HSM A

Distortion for Sigma 20mm f/1.4 DG HSM Art + Examples

Optical distortion is primarily barrel distortion (bowing outward) to the frame edges, then flattening to near-zero distortion to the corners.

Maximum distortion is held to 1.5%, which is outstanding for an f/1.4 design, and actually the world’s best in a fast 21mm as of 2015 (Leica 21mm f/1.4 Summilux-M ASPH has about 2.3% distortion). Indeed, the Sigma 20/1.4 has clearly superior distortion characteristics to the Leica 21mm f/3.4 Super-Elmar-M ASPH, which is 2.5 stops slower! It even beats the Zeiss Loxia 21mm f/2.8, and the Loxia is two stops slower.

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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.

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