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08-19-2011, 01:05 PM   #1
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DA15 ltd: Have I bought a dud?

I finally relented and got this lens... and what a gem it is. I appreciated from my research that this lens is going to have slightly soft edges at f4, but I think the blurred streak down the right hand border looks... unusual. Is something wrong?





At f8 it's much better and I am thrilled with how the scene is rendered generally, but, having seen the shot above, I can see the same soft border on the right hand side



Lens is brand new etc from a UK retailer, so warranty not a problem if the lens has 'issues'. I just want to gauge whether DA15mm think this is normal or...not! If it's just the 'field curvature' of the lens... I can probably work around it

08-19-2011, 02:07 PM   #2
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I had exactly the same problem with a Sigma 10-20--not the usual kind of border softness, but a rather pronounced band of softness along the left side of the pics, even at f8, between 10mm and 17mm... In your case, the problem is on the right side.
Is the left side of pics taken at f4 with your DA 15mm similarly soft?
08-19-2011, 02:12 PM   #3
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Whether its bad or not, you are unhappy with that copy so I would swap it for a new one for the peace of mind.
08-19-2011, 02:15 PM   #4
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QuoteOriginally posted by imtheguy Quote
Whether its bad or not, you are unhappy with that copy so I would swap it for a new one for the peace of mind.
Good advice. I returned my Sigma. (I'll get another one soon.)

08-19-2011, 02:49 PM   #5
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QuoteOriginally posted by imtheguy Quote
Whether its bad or not, you are unhappy with that copy so I would swap it for a new one for the peace of mind.
+1 with imtheguy
08-19-2011, 03:02 PM   #6
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QuoteOriginally posted by causey Quote
Is the left side of pics taken at f4 with your DA 15mm similarly soft?
I think the left side is a little soft but probably within what you would expect at wide open aperture - i.e. not really that noticeable unless you pixel peep. But on the right hand side, it looks like someone's smeared a greasy finger down the border of the picture. I think I will send it back, fortunately I had the fore-sight to buy it from a reputable retailer.
08-19-2011, 05:48 PM   #7
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Did you put any filter on the 15mm? Just curious.
08-20-2011, 03:44 AM   #8
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No, it was fresh out of the box. Looking at some pics taken today, it is actually soft at both sides at f4, slightly worse on the right. I need to get out and take more real life shots before deciding what to do.

08-20-2011, 04:47 AM   #9
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Wide open it IS soft outside the center.

Photozone

08-20-2011, 06:27 AM   #10
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I was expecting softer edges at f4, but not quite such a sudden drop off. (The measurements are still in 'good' territory at f4). Ah well... I'll continue to put it through it's paces... at f8 it certainly catches up at the edges and has a subtle punch that my sigma 10-20m lacks.
08-21-2011, 03:27 PM   #11
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It does not look like a problem to me but like others have said if it bothers you I would return it for a new copy. Thats why we have warranties and it should give you peace of mind.
08-24-2011, 07:54 PM   #12
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I don't think you need more "real life" testing; you need more accurate testing. Try photographing the same object (high contrast letters on a sign, for example) and, without changing the (manual) focus, place the object at the extreme of every side and each corner of the image. Obviously use a tripod (or at least use very, very high shutter speeds, or flash) and have the SR off. Make several tests. Since you apparently have the 10-20mm as well, make the same tests with it, and for optimal results, mix them up (or have someone else mix them up) so you don't know when you're looking at them which lens took which picture.

Paul
08-24-2011, 07:58 PM   #13
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We've got no idea what was the point of focus in either photo, so it's pretty hard to make any judgement to be honest.
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