To many, this review will be a case of preaching to the converted. Pentax's series of "Limited" have acquired legendary status amongst Pentax users, and there will be many who know this model's reputation very well. However, there will be some who are wondering whether it's really worth the money, and there will be others who are wondering what the fuss is all about in the first place.
So I'll start with the fuss. Pentax has two "premium" ranges of lenses, the Limited range and the * range (such as FA* and DA*). The latter range is aimed at working professionals who need top quality zooms and longer-length fast telephoto primes. The Limited range fills the other end of the spectrum for people who want the very best optical performance in shorter and wide angle telephoto lenses. These lenses are compact (some are tiny, such as the 40mm F2.8), and are manufactured to the highest possible standards. They are wonderfully constructed out of metal, and are hand-assembled to ensure the best quality finish.
So, why bother? Well, prime lenses such as these offer the best optical quality available, with absolutely no compromises, and your photographs will reap the benefits of that immediately. The apparent drawback of not being able to zoom is easily solved by, without wishing to sound glib, moving away from or towards your subject, and I actually prefer having a fixed length to work with, as it is easier to visualise the picture in advance.
And the quality? Simply stunning. Colours are rendered quite gorgeously, with lovely bokeh. Contrast is a revelation compared to cheaper lenses, and the focal length of 70mm (equivalent to about 105mm on an old 35mm camera) makes it ideal for portrait work. I've not had this lens long, but I've been blown away by the results.
Quite simply, you won't get a better portrait prime lens for the Pentax system (unless you're in the market for the 77mm F1.8, that is...) You'll love it.