24/1.8: http://www.slrgear.com/reviews/showproduct.php/product/1452/cat/82 20/1.7: http://www.slrgear.com/reviews/showproduct.php/product/1295/cat/all The beloved 20/1.7 is far from perfect (slow and loud AF, non-internally focusing, etc) but seems to have better optical performance overall than the much bigger/heavier, more expensive 24/1.8 Zeiss. Looking at the graphs, the pany is generally sharper even at 1.7 vs 1.8. Both at f/2, the pany gets sharper still where as the Zeiss barely improves. The distortion is seems bad on the Zeiss where as the pany basically doesn't have any (because of SW correction?). Vignetting is a lot better on the Zeiss though. Still, I expected better from this $1000 Zeiss branded lens.