The word on dpreview is that this is Sigma's 24-70 f2.8 scaled down to the APS-C sensor. Here's Pop Photo's review:
http://www.popphoto.com/article.asp?section_id=2&article_id=646&page_number=1&preview= If the link doesn't work, just go to Pop Photo's web site and find the review. The lens looks pretty good at 24 mm, except for f2.8, but less sharp at 50 and 70. Sigma's normal f2.8 zooms have not had the performance of the better ones from Tokina (older 28-70 f2.6-2.8 and the current 28-80 f2.8) nor of the current Tamron 24-75 f2.8. I am wondering when Tokina and Tamron will enter the market for lenses designed for the APS-C sensor. When they do, we may have some very high quality alternatives. Keep in mind that the DA 16-45 is very good wide open. In fact, Pentax's mtf encoding indicates that from 16 to 28 mm., f4 is its sharpest aperture. If the Sigma lens is not that good at f2.8, then one is not really gaining anything over the Pentax by buying it (well, except for being able to brag about having f2.8). Of course, a major advantage to the Sigma lens may be that you could actually buy one. That can't be said with assurance of Pentax lenses. I hope that Sigma takes the excellent 70-200 f2.8 EX and scales it down to the APS-C sensor. I would buy one. It would be a dream come true. Joe
