The Samyang SY10M-P 10mm f/2.8 ED Aspherical Nano Coating System CS lens is a manually focusing prime wide-angle lens specifically designed for Pentax K-mount cameras with APS-C image sensors. With a 35mm equivalent focal length of 15mm and an exceptionally wide field of view of 109.5 degrees, this lens is ideal for interior, architectural, and landscape photography, where comprehensive image field coverage is crucial. The optical construction consists of 14 lenses in 9 groups, including one ED element and two aspherical elements, which work together to minimize chromatic aberrations and distortions while delivering sharp, detailed images. The Nano Coating System on the lenses effectively reduces surface reflections, prevents lens flares and ghosting, and enhances light transmission for increased contrast and color neutrality. The lens features a high maximum aperture of f/2.8, which can be stopped down to f/22, providing versatile exposure control in various lighting conditions. The mechanical aperture coupling allows compatibility with aperture priority and automatic exposure modes on Pentax DSLRs, while the manual focus mechanism offers precise focus control. With a minimum focusing distance of 24 cm and six aperture blades for smooth out-of-focus areas, the lens maintains compact dimensions of 86.11 mm in diameter and 104.65 mm in length, weighing approximately 907 g. The absence of image stabilization and filter threads emphasizes its sleek design, making it a reliable tool for photographers seeking wide-angle performance with optical precision and build quality.