Last weekend, while teaching my Fundamentals Workshop, I talked about the advantages of a fast prime lens for portraits. I often recommend the f1.8 or f1.4 50mm lenses to Nikon and Canon shooters. Pentax has the 55mm 1.4 which is one of their pro-grade DA* lenses. Fantastic quality, and priced as such at US$799.
I used the K3 with the 55mm on the second day of the class as we explored the Yomitan area, and the combination produces a bright clear viewfinder with the ability to get a lovely shallow depth of field and nice bokeh.
In many ways the results are similar to my 645D with the 90mm macro lens. Not the same resolution (however 24 MP is more than enough for most applications), but it is from a smaller, lighter, cheaper package.
I often hear new photographers chatting about wanting to upgrade to 35mm full frame, with the notion that they can’t produce professional shots (either artistically or commercially) with an APS sensor camera. The reality is that APS sensor cameras can give you stunning images, and that in most cases it is vision and lack of practice rather than gear holding a person back.
Of course this may sound preachy and hypocritical, coming from a person who A) wants you to take his workshops B) hopes you buy more gear using his affiliate links (right of the page) and C) plans to get a 645D II as an upgrade to an already amazing 645D.
So after several posts all about gear, remember the most important thing is just to pick up your camera, take some photos, and enjoy it.