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Zeiss ZM 15/2.8 Distagon

MTF: 15mm f/2.8 Distagon

MTF charts suggest that there is almost no change in performance from f/2.8 to f/5.6 with fine detail, and a small loss of overall contrast (due to diffraction). This indicates an outstanding lens.

However, the MTF charts do not seem to agree with real-world results, see the examples, which show a marked blurriness at edges and corners which takes f/11 - f/16 to overcome. This is most likely due to ray angle to a digital sensor; MTF charts are for the lens by itself on an optical bench and the sensor can have its own requirements for performance.

There is a strong astigmatism present with the 40 line pairs/mm MTF. It’s likely that this is responsible for the blurriness seen at edges and corners, but by the same token it should be present much more centrally (eg 10mm offset), which suggests again that the sensor is involved also.

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Diglloyd Guide to LEICA contains in-depth coverage of Leica M system cameras and lenses, with additional coverage of Leica M Monochrom, Leica Q.

Special emphasis is placed on Leica M lenses and certain Zeiss ZM lenses.

  • Make better images by learning how to get the best results right away.
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  • 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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Aperture series 2.8, 5.6 available in full article

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