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EXCERPT page containing first few paragraphs. 2018-09-19 01:03:31
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Sigma 105mm f/1.4 DG HSM Art

Color Shift with Stopping Down, SpyderCHECKR Card

See also the Mireds and Color Temperature Table.

This page uses a SpyderCHECKER® color checker card to evaluate the difference in white balance and tint between f/1.4 and f/2 with the Sigma 105mm f/1.4 DG HSM Art, using Photoshop/ACR raw file conversion.

The difference is significant with the resulting sickly yellow-green hue if the same white balance and tint are used for f/2 and other apertures as for f/1.4. Exact figures are given for white balance and tint, but what one does for f/1.6 and f/1.8 is an exercise left to the diligent reader.

What a JPEG shooter can do about this color shift is not much, if the choice of aperture changes. Otherwise, compensation can be dialed in, once one discovers how the D850 auto white balance behaves and/or fixed white balance. Shooting a gray card (in focus!) is thus advised for JPEG shooters.

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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.

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.

Variants f1_4_neutral,f2_neutral,f2_SameAsF1_4 available in full article
f1.4 @ 1/400 sec, ISO 64; 2018-07-11 18:23:57
NIKON D850 + Sigma 105mm f/1.4 DG HSM Art

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