Originally posted by czech user http://www.photozone.de/Reviews/298-sigma-af-30mm-f14-ex-hsm-dc-test-report--review?start=2
Oh, is optical quality so awful ? Two stars??
I think it's a great lens in terms of optics. Edge-to-edge sharpness is admittedly not its strong point, but it is very sharp in the center and is actually one of the sharpest lenses at f/1.4 you'll find anywhere, even sharper than the 31mm ltd. I tend to think the amazing center performance, at the expense of edge sharpness, was probably a conscious design choice when they were deciding what's most important in a good, affordable, large-aperture lens. It's become one of my favorite lenses, and I love the images I get from it.
I like Photozone, but I agree with Adam's assessment about them sometimes over-quantifying things. When you're talking about an art like photography, objectivity only goes so far. And giving such a great lens two stars really doesn't tell the whole story.
I also think that the people at Photozone also tend towards a different style of photography than me, so they may value something like edge-to-edge sharpness much more than I do. Their sample photo galleries are usually filled with street photography, architecture, and pictures of inanimate objects. You rarely see people as subjects in their photos, and portraits are rare. (I sometimes wonder if the reviewers don't have any friends or families!) Whereas I am shooting people more often than not, and so for people and portraits edge-to-edge sharpness is often irrelevant and is certainly much less important than sharpness towards the center of the frame.