EXCERPT page containing first few paragraphs. 2023-03-29 05:41:02
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Lens Designer Notes
These notes are straight from the lens designer, J. Brian Caldwell, Ph.D., of Caldwell Photographic Inc, in response to questions posed by Lloyd Chambers of diglloyd.com. Italicized type indicates lens designer comments.
The lens was optimized for a flat image plane for both distant and close object distances, and there is very little to be gained by allowing the image plane to curve, or equivalently considering a curved object plane. If you look at the MTF curves for infinity focus that I put in the online brochure you'll see that at f/5.6 there is essentially no drop in performance over the DX format (~29mm diagonal), and only a very small performance drop in the outer parts of the FX format (43.2mm diagonal). So, at f/5.6 you probably will have difficulty detecting any field curvature at all.
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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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