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03-13-2019, 05:58 AM   #226
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QuoteOriginally posted by Digitalis Quote
Your copy might be decentered.
New copy is on the way, I hope it will have sharp edges at 18mm!

03-13-2019, 12:10 PM   #227
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QuoteOriginally posted by Digitalis Quote
I don't think we ever will. Sigma will say it has something to do with Pentax AF and Pentax will say it has something to do with Sigmas electronics.

Interesting. Early on at least (and I haven't checked in a long time) there were reports of similar focus issues on Nikon and Canon which is why I never took Sigma's explanation as gospel.

Focus problems with Sigma 18-35mm f1.8 A on Nikon D7200: Third Party Lens Talk Forum: Digital Photography Review (loads of nikon complaints - mostly about non-central focus points but even center focus point issues come up. )

And decentering seems to be an issue with the non-pentax copies also.
03-13-2019, 12:59 PM   #228
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The only people I haven't heard complaints from about this lens are the sigma camera crowd. Either none of them use this lens (unlikely) or there aren't enough of them to make much of a stink about AF inaccuracies - and Sigmas PDAF is said to be at the same tech level as the K10D.
03-13-2019, 02:08 PM   #229
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QuoteOriginally posted by Digitalis Quote
The only people I haven't heard complaints from about this lens are the sigma camera crowd. Either none of them use this lens (unlikely) or there aren't enough of them to make much of a stink about AF inaccuracies - and Sigmas PDAF is said to be at the same tech level as the K10D.
LOL - good point.

03-23-2019, 08:01 AM   #230
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QuoteOriginally posted by Digitalis Quote
The only people I haven't heard complaints from about this lens are the sigma camera crowd. Either none of them use this lens (unlikely) or there aren't enough of them to make much of a stink about AF inaccuracies - and Sigmas PDAF is said to be at the same tech level as the K10D.
Not quite, I have a friend that used this lens with a SD1 Merrill and it's absolutely tack sharp. I also have a SD Quattro and, again, no issues.

I have no clue of why this lens works so well with Sigma's bodies and so randomly crazy with other ones.
03-23-2019, 12:08 PM   #231
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QuoteOriginally posted by superdave Quote
New copy is on the way, I hope it will have sharp edges at 18mm!
New copy was worse than first one, serious decentering, right side was super blurry.... Default focus using the viewfinder result in bokeh everywhere... I returned it, and I will retry in another store...
03-23-2019, 12:13 PM   #232
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QuoteOriginally posted by superdave Quote
New copy was worse than first one, serious decentering, right side was super blurry.... Default focus using the viewfinder result in bokeh everywhere... I returned it, and I will retry in another store...

I checked mine and I didn't notice any problems like this one, just the focus issue.
03-23-2019, 01:12 PM   #233
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QuoteOriginally posted by AntonioS Quote
I have a friend that used this lens with a SD1 Merrill and it's absolutely tack sharp. I also have a SD Quattro and, again, no issues.
I don't think any of us were disputing the sharpness of the 18-35mm f/1.8 - it's one of the sharpest lenses I have ever worked with. Interesting to hear the AF problems are non-existant on Sigma cameras.

03-23-2019, 05:02 PM   #234
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QuoteOriginally posted by Digitalis Quote
I don't think any of us were disputing the sharpness of the 18-35mm f/1.8 - it's one of the sharpest lenses I have ever worked with. Interesting to hear the AF problems are non-existant on Sigma cameras.
Yes. I love and hate mine, specially because it works well on the K5-II and very unreliable with the k3-II. Very frustrating.
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