Summary: Photosite spacing of 1.5 µm or less is common for smart phone cameras; and 1-inch sensors in cameras such as the the Sony RX100 III have photosite spacing of 2.4 µm. Diffraction-limited line-pair resolution is given for photosite spacing as little as 0.5 µm. Two micron photosite spacing implies APS-C and “full-frame” (FF) sensors with 94 and 216 MP, respectively. In order to approach the theoretical resolution limits of sensors with 2 – 3 µm photosites, it will be necessary to have lenses that perform exceptionally well at apertures f/2.8 – f/4. It is not clear if such lenses can be manufactured at reasonable cost for APS-C and FF sensors. If it is, it may be necessary to sacrifice large maximum apertures, such as f/1.4, in order to make “slower” but sharper lenses. With current technology, 2 – 3 µm photosites will entail a trade-off between resolution and low noise, when compared to current FF and APS-C sensors. For most image uses, 100 MP or greater resolution implies capture oversampling. That is, images will be down-sampled for “final”use. It is suggested that such down-sampling may produce a sharper and less noisy final image than could otherwise be obtained by capturing images at lower initial resolution.
Key words: resolution limits, sampling frequency, diffraction, sensor pixel size, photosite size, perfect lens, line-pairs, simulation, oversampling, sharpness, signal-to-noise ratio, down-sampling, image noise, edge acutance