S23 ULtra x10 Periscope Camera Resolution

S23 Ultra x10 Periscope Camera Resolution

May 25, 2024

Resolving detail in images using the S23 Ultra x10 periscope lens depends on the fundamental optical diffraction limit determined by the lens aperture (diameter) and the pixel density of the sensor. The FOV (field of view) of the periscope x10 lens (without extra zoom) is 8.6x6.5 °. The lens aperture for the f_eq = 230 mm periscope lens is 4.9 mm. The corresponding Dawe's limit angular resolution due to diffraction is 116/4.9 = 24 ∠". The 12 Mp sensor quad-pixel lateral size corresponds to an angular width resolution of ~ 8 ∠". This means that, for the x10 periscope camera, the image angular resolution is limited by the lens-size diffraction limit.

As a basic test of the x10 periscope camera lens performance, the first picture is a photo of the star Arcturus. The full high resolution 3000x4000 photo is at left (click to view/zoom/download the image). At right is a zoom-in pixel level view (using Win11 Paint). The visibility was fair with very steady viewing. The manual focus was adjusted very carefully. The zoomed star image shows a width of ~ 8 pixels (or ~ 64 ∠" about 2.5x Dawes limit).
Camera settings were: Tripod x10 Periscope Pro Mode t=1sec ISO-200

To test in a more controlled condition, an image of a single white square of 7x7 pixels was drawn (using Win11 Paint) on a black background of dimension 1440x2900 pixels, the display resolution of a S9 smartphone. When this image is displayed on the S9, it displays as a solid white square with a physical width of ~ 0.3mm. The S9 smartphone was placed at a distance of 26'2" (7976 mm) from the S23 Ultra phone. At this distance, the white square on the S9 subtends an angular width at the S23 Ultra of 7.7∠" which for the S23 x10 periscope camera, corresponds to about one quad pixel of it's sensor. So this is a reasonable test of a light source at an infinite distance. The S23 x10 periscope camera photo taken of this S9 "star" display is shown at left (click to view/zoom/download the image) and the corresponding zoomed in to pixel level is shown at right. The zoomed white square image shows a width of ~ 4 pixels (or ~ 32 ∠" about 1.3x Dawes limit).

Note that tripling the diameter of the x10 camera lens diameter from 5mm to 15mm would improve the Dawe's resolution limit from 24 ∠" to 8 ∠", comparable to the pixel angular resolution, as well as increasing the light gathering power by almost x10.