EXCERPT page containing first few paragraphs. 2021-08-01 04:17:11
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This page assesses the Sigma 105mm f/1.4 DG HSM Art for focus shift at a distance of approximately 1.5 meters.
One might think that a “small” amount of focus shift is acceptable. But it is not—I think I at first unfairly blamed the Nikon D850 for focusing errors in the f/4 and f/5.6 images. It might well be a factor, but the dominant error is the zone of sharp focus being too deep, e.g., centered inside the eyeball instead of centered on the iris of the eye. This series explores that possibility
Picnic table wooden surface
The entire frame aperture series is shown below. A casual glance show a hint of a focus shift issue, but it’s not very obvious.
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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.
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- Workflow discusses image organization, raw conversion and post processing. Many examples show processing parameters for direct insight into how the image was converted.
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- 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.