I bought this for $18 "new other" on Ebay. I wanted a Pentax PK mount but this turned out to be OM-mount. Apparently CPC was the umbrella company that owned Pentax and this lens was supposed to be the same but without the SMC coatings. Pentax made a 28mm f2.8 non-macro that I'd like to try out and compare to this lens. Unfortunately I'm seeing a lot of what I think is chromatic aberration in some of the photos, but not all. I must say I'm a bit confused by the lens's performance. At 2.8 it is visibly soft. There is no f3.3 (but half-stops thereafter). At f4 it gets much sharper. F5.6 or f8 don't get any sharper. Not even the corners. Odd. I took the photos on the PM2 (one of the best sensors on the market today IMO) and at 16MP some of the lens's problems are visible. If I keep it to 8MP, however, the images look very good. It does well on macro photos. Since the center is sharp it'd be the perfect choice for a cheap macro lens. Colors are nice too as you can see below. It focuses within about 3". I'm very happy with the focal length and the fact that I spent just $18. I now have the Vivitar 28/2 Close Focus and the Sigma 30/2.8 so I doubt I'll ever use this lens again. For now it's mounted on my old OM-1 on the shelf. Here is my CPC 28mm f2.8 Macro Flickr page with as of now a good 50 photos taken with this lens. Sorry that they're only 2MP. I don't want to upload the huge originals but if someone wants any feel free to PM me. Below is what she looks like on the camera. Any questions about this cheap but decent lens feel free to ask!