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EXCERPT page containing first few paragraphs. 2023-02-03 05:45:34

Color uniformity and Lens Correction

Leica M lenses have historically been designed without regard for ray-angle: the angle at which the light strikes the film or sensor. Ray angle is of little consequence for photographic film, and it allows freedom in optical design that can be used to increase performance in other ways. The ray angle is determined by the exit pupil of the lens, but is rarely specified (but see table below).

The ray angle, combined with the centering of sensor and lens with respect to each other, as well as the sensor design itself, all combine to produce more or less vignetting and off-center color shift, which might not be symmetric in effect.

A digital sensor is a much more demanding medium than film: digital sensors work best when light rays strike the photosites at 90°. In addition, infrared contamination must be dealt with using relatively thick infrared-blocking glass; this was a serious problem with the Leica M8 that caused much consternation among its users, with Leica scrambling to offer infrared-blocking filters of various sizes after the M8 shipped.

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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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  • 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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Ray Angles for the most of the Zeiss ZM line
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