The NiSi 15mm f/4 ASPH ultra-wide angle lens expresses all of NiSi's expertise in optics. A lens that focuses on first-class features and concentrates on the essentials - the quality of the materials used and the quality of the glass. Full metal barrel, precision optical glass for excellent sharpness throughout the field of view, construction with 12 elements in 10 groups, plus a double-sided aspherical element and two very low dispersion elements, are just some of the features of the NiSi 15mm f/4 ASPH. Below are the most important features. The lens aperture is designed with 10 straight blades that allow for sun stars from F4 to F22 with optimal image quality throughout. This overturns the preconception that you need a small aperture to produce a sunstar. Additionally, there is a mechanical aperture ring with manual and stepless adjustment, perfect for precise adjustment and use in videography.