EXCERPT page containing first few paragraphs. 2018-07-17 12:09:30
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This aperture series from f/4 through f/11 is an an exceptional demonstration of wild and whacky field curvature and focus shift, yet with outstanding image quality if one is willing to accept and work with these behaviors in the field. Tips for field use follow in the conclusions.
Depth of field tables are useless fantasy for a lens like the Sigma 12-24mm f/4 DG HSM Art. Image quality in practice depends strongly on focus placement in a scene and how that is optimal for the subject matter, which must also take lens behavior into account.
Especially at 36MP on up, the photographer must place focus wisely for the subject matter, not just the “1/3 in” rule and not even just the near/far relationships, but also anticipating and compensating for a lens with focus shift and field curvature, which requires special care based on the shooting aperture.
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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 28 megapixels filling up to 5K display, 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.