Originally posted by JHD Two questions...
How close to the edge is does one have to get before those numbers become meaningful?
How much more does the Zeiss 18mm T* Distagon f3.5 cost than the Sigma 30 1.4?
The price of the Sigma is in DA 15 & 21mm ltd range and isn't even close in ltd build quality. I don't pixel peep in the edges a lot. However, the 30 is too close to being a 'Normal' field of view on aps-c bodies. However, it one is on a budget and the ~ 30mm is acceptable, the FA 35mm is something to consider or even the F 28mm. However, when someone is looking in the teens and says they want the sharpest wide angle lens available for a Pentax, the Zeiss has to be mentioned. It costs as much at present as I have in my DA 21, DA 35 and FA 77mm.
Granted I got the 1st 2 before the price jump.
Edit: My god, look at the center numbers for that T* 18mm.