影象之極致 Pentax f4 25mm廣角鏡頭
the latest optical system uses two aspherical lenses (including one double-sided aspherical lens) and the new Aero Bright Coating for significantly reducing the surface reflections. This minimizes the various types of aberrations while also providing a unique expressive result based on the strong perspective, wide angle of view, and impressive depth of field that is possible only with super wide angle lenses. A round iris diaphragm up to F8 is used for natural rendering of out-of-focus (bokeh) effect for point sources of light