Samyang's manual-focus ultra-wide for Sony E APS-C — same as Fuji X version, 18mm equiv for astrophotography.
The Samyang 12mm f/2.0 NCS CS is a manual-focus APS-C wide prime for Sony E-mount (CS = Crop Sensor), providing a 18mm full-frame equivalent perspective. No autofocus motor. Twelve elements in 10 groups with 2 aspherical elements. Six rounded aperture blades. 67mm filter thread. At 245g. 0.20m MFD.
The optical design uses 12 elements in 10 groups with 2 aspherical elements. Six rounded aperture blades. The 67mm filter thread. At 245g the lens is moderate. Minimum focus distance of 0.20m. Manual focus only — no autofocus motor. f/2.0 maximum aperture. APS-C image circle (CS designation; not for full-frame use).
The 18mm equivalent at f/2.0 is the primary use case for the Samyang 12mm: astrophotography and nightscape photography on APS-C bodies where f/2.0 at a wide-angle focal length collects more light per unit time than f/2.8 alternatives. The 0.20m MFD enables close foreground environmental compositions. Manual focus precision is critical at f/2.0 for star field sharpness.
On the used market the Samyang 12mm f/2.0 NCS CS is affordable as a compact APS-C manual-focus wide prime. Condition checks: manual focus ring smoothness, 67mm front element for marks, aperture ring operation. Manual focus only. APS-C only (CS). Compatible with Sony E-mount APS-C bodies.