Originally posted by winglik
This is a picture from a user on flickr for the Sigma mini wide 28mm, it has pretty good macro as well, but from the pictures posted here, the Vivitar looks much sharper and has better macro.
Thanks for the sigma wide pic...
I am not sure, that sigma shot you posted looks really sharp to me... one of the advantages of the K20 14mp sensor is that I can crop way in and still have a ton of pixels to work with in PP. The eye shot of mine is testament to how well the K20d hold up to the crop.
I would bet that sigma shot is probably really sharp at full res.