I like my Sigma 12-24 UWA. However it has some limitations. It's rather slow for indoor use (f4.5 at 12mm, going up to f5.6). The built-in flash on Nex severely vignettes in direct mode, and isn't always strong enough when bounced (and there's not always a ceiling close enough to bounce off of). It does work great with an external flash. But, it's an expensive full frame lens, and I think a lot of it's benefits are lost on my Nex 6. Now, most people would probably use it for the landscapes, so they would shoot it at f8-f11 anyway. I however would like to be able to use it on the inside, too. Since I am not planning on moving to FF anytime soon, I could sell this lens and get Tokina 11-16/2.8 in A-mount. I would lose the ability to use it on FF, and 17-24mm range. I would however get a lens that's a bit lighter, a bit smaller, fast enough for in-house use without a flash, and will probably save some money, too (so can feed something else to my GAS syndrome ). Seems like Tokina is decent optically. My Sigma is in pristine condition, save some small nicks on the removable part of the hood, and with so many people moving to FF I think I should be able to sell it rather quickly. So, what do you think ?