Originally posted by LeChuck Sigma 8-16 is not a very useful range for me, and Rokinon 14mm on APSC for me is borderline wide, but not wide enough. It is probably the lens I'm going to go for next, though, after trying several other alternatives (including the Pentax DA 15mm). I'm looking for as much sharpness corner to corner as I can have, as little CA as I can, and a good usable range.
I also have to say I used to own a Sigma 10-20 on my K5. It worked fine but would not be sharp enough for my wish to make larger prints. I recently tried 2 Sigma10-20s and they were both horribly decentered, and I gave up, not willing to try another Sigma zoom. I then tried a Pentax 12-24. Terrible form factor, too expensive, just not quite wide enough, and terrible CA all over the place, as well as purple fringing (my fisheye does better even in the most deformed areas), then the DA 15mm (don't get me started on that). Left is the Samyang/Rokinon 14mm, which I can probably use, especially for stitching, but for me at this point it would be a full frame that would suit my needs/wishes.
Really look at the Sigma 8-16. It's sharp, it's corrected, as in no barrel distortion from 12-16, it has lower CA than many primes, and you'd be surprised how often you use 8mm when you have it. The only problem is, because of the corrected distortion, if your wife gets in the frame it will make her look shorter than she is a and thicker than she is, and if you should not get a picture of her deleted before she sees it because you were laughing too hard, you're going to suffer. Trust me, I know of what I speak.