Anyone having the lens is welcome to post pictures taken with it in this thread. Maybe as a reply to this post and with your own text in the Subject line.

Part 1: The lens

I know several posters here has the Sigma 30/1.4. It is not very often spoken about and I am not sure why.

The build quality is good, nothing flimsy about this lens at all. The focusing ring is not super smooth. It isn't obvious at first but when focusing manually very carefully one can feel a minor grittiness. The AF is "fast", approximately the same as with the FA35/2. Sometimes there is a final adjustment before locking but with the camera in AF-C this is of no concern. There is no QucikShift in the Pentax mount version of this lens so when switching between AF and MF it behaves the same way as the FA31 or the FA35.
(Olympus users get a better thing; there it sports an HSM motor and Full Time Manual override.)
It comes with eight aperture blades inside, an overdimensioned lens bag to wrap it up in and there is a plastic petal type hood that completes the package. At the front we have a standard 62mm thread for filters or alternative hoods. All in all everything is pretty decent. The lens is "big" compared to slower options but not too stupid big. Check Photozone for pictures:

I bought this Sigma 30/1.4 some time ago. This is the very lens tested by Klaus at Photozone, here:
http://www.photozone.de/8Reviews/lenses/sigma_30_14_pentax/index.htm

Not bad... A resolution all time high lens on the K10D. Bad corners and weak borders but that doesn't bother me much for a low light lens. And stopped down to f/8 everything should be at least OK.

When Klaus had tested the lens and I got it back the K10D was at repair (front and backfocusing troubles) and when the camera came back everything was fine until I tried to stop down and use apertures between f/2.8 and f/8.

So, what was the error? More about this is Part 2.
LBA picture in Part 3.

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Jonas