Well know lens, many people says the best lens in  Asahi  Pentax product line.color rendering, sharpness, "bokeh" just excellent. SMC Takumar 1.8/85mm very well built mechanically, real competitor of another famous lens: Carl Zeiss Jena Pancolar 1.8/80mm. Perform well as close-up and portrait lens.This lens have full aperture meter coupling (for Spotmatic-F, ES full aperture metering system).It has a little tricky Auto-Manual switch you can switch to any position if lens mounted on right Asahi film camera.In any other situation to change mode need to push a little button on the mount surface.Almost every maker best lenses are in this focal length I have many of them like Carl Zeiss Jena Biotar 75mm f1.5, Carl Zeiss Jena Pancolar 80mm f1.8, Nikon-Nikkor-H 85mm f1.8, Helios-40 85mm f1.5.They have not much quality difference, but each lens has own personality. This Super-Multi-Coated Takumar has the best out focus background "bokeh" from all of them. Biotar 75mm f1.5 the best wide-open performer you can't see any visible difference lens is stopped down or not in sharpness. I have the latest version of Takumar 85mm f1.8 with K-bajonett also, M42 version is significantly better as the price shows on the market.