This lens comprises 6 elements in 5 groups and features PENTAX original super multi coating (SMC). SMC describes seven microscopically thin layers of high quality coatings that are applied to the lens elements. SMC coatings significantly increase the amount of light transmitted by the lens. This lens delivers abundant colourcolor gradations and sharp, crystal-clear images with a sense of transparency. When the aperture is closed, subjects near and far can be captured with tremendous sharpness and clarity. The smc PENTAX-FA645 75mm F2.8 lens provides excellent, soft, out-of-focus (bokeh) effect for backgrounds with its F2.8 open aperture, which is a feature unique to this focal point distance. Weighing only 215g, this lens allows extreme portability. Compatible with both film and digital PENTAX 645 cameras.