"＜Main features of HD PENTAX- FA Limited ＞ １．HD coating for upgraded imaging performance. This lens features Pentax-original HD coating.* Compared with conventional multi-layer coatings, this high-grade, multi-layer coating assures higher light transmittance woth minimal reflectance , while effectively minimizing flare and ghost images even in demanding lighting condition such as backlighting. this coating further upgrades the imaging power of this limited-series lens for multi-improved sharpness. *HD stands for High definition. ２．Eight-blade circular diaphragm for beautiful light beam and bokeh effect This lens incorporates a newly designed diaphragm unit with a circular diaphragm which produce a beaytiful bokeh effect at open and larger apetures. ３．A top-grade lens with optimised image rendition and fine texture True to the design concept of the limited series, this lens was developed with the goal of providing a distinctive visual expression. This could be achieved only by conducting a series of image quality assessments using a great number of captured images, along with various numerical evaluations using measuring instruments. To make the exterior design more attractive, the lens barrel , hood and cap have been meticulously machined to perfection. The lens itself is finished with the utmost attention to texture, including Shippoyaki-finished mount pointer to enhance the ease of lens mounting. ４．Others ①SP (Super Protect) Coating to keep the lens front surface free of dust or stains ②Serial number assigned to each lens (from 0000001 for the black model; from 1000001 for the silver model ③With aperture ring, each functiion of K mount film SLR camera can be used. "