Wide-angle weather-reistant lenses for Pentax?

Sir Autofocus wrote:

After testing the Sigma 10-20 4-5.6, Pentax 12-24, and Sigma 8-16, here's my ranking of how much I liked them.

3. Sigma 10-20 4-5.6. The cheapest of the bunch. It has purple fringing and other undesirable quality issues. Sigma also makes a 10-20 3.5 which I hear is better but I didn't test it. I would recommend avoiding the Sigma 10-20 4-5.6.

2. Pentax 12-24. In initial testing, it had noticeably better IQ than the Sigma 10-20. I found it for a little less money than the Sigma 8-16, and if someone wants a 12-24 zoom range then my impression is that this is a good choice.

1. My favorite of the group is the Sigma 8-16. It offers the widest zoom, and the IQ seems to be comparable to the Pentax 12-24 in my testing. I'll need to figure out how to deal with the distortion effects that happen at wide angles, but I'm told that this can be done with software. The lens colors and sharpness look good to my eye. I found my copy for slightly more money than the Pentax 12-24, but the wide-angle zoom advantage is so significant that I think it's money well spent.

I had all three lenses over the past years.

Yes, the Sigma 10-20/4.5-5.6 is really the weakest in terms of IQ among the three.

I replaced it later with the Sigma 8-16, an amazing UWA zoom lens. The corner performance is not optimal, but it can be managed by trying to be careful when framing, avoiding too busy areas in the corners. The main problem however was the lens was unable to provide correct focal length when below 10mm. IIRC, the lens reported 510mm and 395mm for 8mm and 9mm, which forced to deactivate SR on the K100D. Newer Pentax cameras ignored these out of range focal lengths.

My favorite was however the DA 12-24, best consistent IQ from corner to corner and full functionality. However, as it lacks weather sealing, a three weeks trip in the Central Kalahari desert was a bit too much dust for the light construction.

The best UWA solution I had on the APS-C Pentax camera was the DA15.