Rokinon AE85M-C 85mm F1.4 Aspherical Lens with Built in AE Chip for Canon DSLR Cameras (Black)

This is one of those rare lenses that proves to be relatively cheap, but also very very good. I have the Falcon version but it comes in many different brand names including Samyang and Vivitar.First thing to note is that on a Pentax mount it works in aperture priority (Av) mode, so you can set the aperture with the camera dial (you can on my K5 anyway). This is handy as the aperture dial itself is tricky to get to as its very small and recessed. The focus method is manual on these, but it is very smooth and not at all lose, so you are confident the barrel stays where it was put. Additionally I get focus confirmation in the viewfinder with this lens which is useful (the little red dot confirming the subject is in focus).The picture quality is simply stunning, and the bokeh is to die for - many call this lens the bokeh monster. Simply go and flickr to see what I mean. It does take a little getting used to, as at 1.4 the depth of field is tiny, but once you do it's a joy. All of my best portraits have been taken with this lens. It also gives amazing quality feel to video, as the same narrow depth of field is transferred to the video format. I found I could change the aperture whilst the video was shooting too.Simply amazing value for money, you would spend 3 times for a pentax version, which is marginally better, but no where near 3 x times better. Buy one, you will not regret it!