Standard 45mm prime lens with an f/1.2 aperture.. Large-diameter mount and short back focus, combined with digital distortion correction, result in a compact and reasonably priced f/1.2 large-diameter lens.. Bokeh, enabled by a large-diameter lens, allows users to create images with a three-dimensional look, isolating subjects from the background.. An aperture of f/1.2 allows for faster shutter speeds in darker situations.. Effective placement of one PMo aspheric lens reduces aberrations (a first for Canon in a f/1.2 lens).