[maxloxton]

Hello,

I am about to acquire Sigma 12-24 first version of the lens despite the fact that I have Pentax 12-24 f4. I am just thinking that with Pentax Full Frame around the corner I will be able to use Sigma 12-24 as WA. Anyone using Sigma 12-24 can share their experience with respect to sharpness and IQ.

[G_Money]

DA 12-24mm vs Sigma and Tamron 10-24mm Comparison Review - Introduction | PentaxForums.com Reviews

[nomadkng]

I owned the Sigma for about 2 years. I really enjoyed the image results, the IQ was professional quality on a K5iis.
The edges suffered from distortion issues, as most UWA lenses do. I would still own it now if not for 2 issues:

The lens hood acts as a screw in filter holder, but its not useable from about 15mm - 12mm on APS-C, it completes blackens the corners, giving a "looking through a portal" appearance.
The only other way to utilize a filter is gel inserts in a small holder at the rear of the lens. I find gel filters cumbersome and tricky to use in the field and I don't trust their quality compared to high end glass filters.

Since I shoot waterfalls as roughly 50% of my landscape portfolio, CPL and ND filters are a must have. The 12-24 can't accommodate them (for all intents and purposes/to my satisfaction)

Thus I sold it, begrudgingly.