The DA17-70 is somewhat sealed, nothing compared to DA* but better than previous 'normal' DA's. I'd say, weathersealed 'à la Canon 5D' ?
The 16-45 is Screwdive ONLY and the 17-70 is SDM ONLY, which means no AF on K100D and previous DSLRs. Chasseur d'Images complained that the QuickShift wasn't a true one (compared to other DA's) but I never touched a 17-70 so can't say more. AFAIR the IQ is OK considering the target of the zoom but distortion is well... distorted I think more than 16-45. Mechanical construction is about the same. I started a thread on Pentax Forums months ago when Chasseur D'Images tested 20 Pentax lenses. You will find comments including the 17-70: http://www.pentaxforums.com/forums/everything-else/27942-chasseur-dimages-test-20-pentax-lenses-k20d.html I think choice between the two will be based on: - price (16-45 easy to find 2nd hand, not the 17-70) - WA requirements against zoom range. - older bodies it might be used on ? Best REgards, -- Thibault Massart aka Thibouille ---------------------- Photo: K10D,Z1,SuperA,KX,MX, P30t and KR-10x ;) ... Thinkpad: X23+UB,X60+UB Programing: D7 user (trying out D2007) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
