EXCERPT page containing first few paragraphs. 2023-02-08 02:33:54
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Vignetting is substantial at f/1.4 (about 3 stops into the extreme corners), but this can be an asset to drawing attention to the center or to acting as a neutral density filter off bright peripheral subject matter. By f/4, the vignetting drops to about one stop into the extreme corners.
Stopping down to f/2 improves illumination over most of the frame considerably, and by f/2.8 the illumination is at the best possible level to the long frame edge. At f/4 there remains a trace of vignetting into the extreme corners, which is hardly different (nearly invisible) versus f/5.6.
The graph below shows the illuminance in the frame for the first 5 f-stops. The curve for f/5.6 is the best possible limit for the most even illumination, because the cos^4 power law governs the brightness thereafter.
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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.
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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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