Originally posted by tibbitts At some point you can wear your camera body out shooting resolution tests at every focal length, focus distance, etc. (I think I almost did between these two lenses and all my copies of the 55-300.) The traffic sign tests were night and day different between the two copies of the lens, and consistent and repeatable. The first copy was just consistently and obviously bad on one side - there was nothing mysterious about it.
I'm with you on that 100%. I'm not a pixel peeper. Like a moron I deleted my example shots, so can't share anything to show the issue, but this isn't a pixel peeping issue. This is a "wtf is wrong with that lens" issue that is glaringly obvious at any view size larger than an Instagram photo on a cell phone. It isn't just totally blurry, but the rectilinear correction seems grossly off on the left side, hugely pulling down and distorting objects on the left side about twice as much as on the right side. Both these issues improve slightly after F7 and above 12mm, but are no where near satisfactory and, in fact, given that these settings make the right side look so nice, the left side issues (while better than wide open at 10mm) stand out even more.
As for the decentering. I have seen numerous threads on other camera boards where owners claimed Sigma did fix their decentered element issue (not sure how), but in those cases Sigma correctly identified the issue as decentering rather than this "needs AF data adjusted".
Quote: By "cheap", I was only refering to its actual price and not its overall quality. This lens can be had today for about 300$ or even less if you're lucky. Which is cheap for a UWA zoom, or even relative to lenses in general...
I've never seen the f4-5.6 version of this lens new for less than $480. The consensus seems to be that the f3.5 is inferior and that one goes for as low as $260. I bought this f4-5.6 one used for $165. If I can pay Sigma $125 to get it working properly I think that's well worth it. What I don't want to do is double down on a poorly constructed copy if their "repair" isn't going to do anything to help the issue.