Originally posted by civiletti I shoot mostly manual focus primes on a tripod. The Photozone tests and some others convinced me to get the 8-16 rather than the DA12-24 or any of the primes. I am still surprised by the level of detail resolved in close inspection, as well as well-controlled distortion for such wide angles. I was concerned about the bulbous, filter-prohibiting front element, but it has not been a problem. Except for the CA, which is manageable in post-production, the DA12-24 is also excellent. I am not familiar with the Sigma 10-20.
I understand why you chose the 8-16: tests are the most convincing I have seen. The only reservations with the 8-16 is non-access to filters, & vignetting--otherwise, the lens is a dream. When I bought into UWA, there was only two choices: the 12-24 or the 10-20 f4-5.6. I spent 2 months researching each, examining as many shots as I could. In the end, for me, the Sigma was the better choice. I agree with you, the 12-24 is an excellent lens--I wouldn't argue against that.
The 12-24 handles vignetting better than Sigma UWAs. If someone said the numbers are meaningless, the 10-20 handles vignetting better than the Da, that is as silly as the aforementioned claim that 12-24 handles Ca better, despite the numbers. Some things are simply not subjective, not even if we want them to be.
In the end, the choice of one lens over another is a harmonious blend of several factors, like statistical evidence, rendering preferences, costs, focal range preferences, personal tastes, & build quality. The factors will be weighted & prioritized differently, according to each buyer's needs. Hence, one buyers' choice can only be seen as best for that buyer, not best for all.
We can offer accurate knowledge to the OP, along with our personal preferences--BUT, we must be clear to delineate between the two.