Summary: The effect of diffraction blur on resolution of black and white line-pair images is modeled by aggregation of a large number of blur circles. The contrast ratio of the line-pairs declines to 50% when the blur circle diameter is about 79% of the width of a line-pair. Contrast falls to about 7% when the blur circle diameter reaches 115% of the line-pair width. These results imply aperture-specific diffraction-limited resolutions. For example, with 50% contrast, the theoretical limit of image resolution is approximately 209 line-pairs per millimeter (lp/mm) at f/4. No other sources of blur are considered. Results are compared to calculated aperture-specific resolution limits published elsewhere. Resolutions obtained here by simulation are less than those calculated from “standard” formulas when line-pair contrast is 50% or less. However, in the case of high contrast (80%), simulated resolution limits are greater than values obtained by formulas. In order for cameras with “full-frame”, APS-C, and m4/3 sensors to achieve resolutions closer to the theoretical diffraction limits, it will be necessary to increase the number of sensor photosites several-fold. It is not clear how much, if any, improvement will be required in lenses.
Key words: diffraction blur, Airy disk, diffraction-limited resolution, sensor-limited resolution, line-pairs, Zeiss Otus 55mm f/1.4, Nikon D800E, Clarkvision