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Old Jun 10, 2010, 5:41 PM   #11
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My Sigma 10-20mm f/4-5.6 arrived today. The lens is extremely soft wide open, and "not bad" stopped down to f/13... perhaps it's a bad copy (probably why the guy was selling it) but it's virtually new and is still under warranty, which is a good thing.

Couple of questions about lens softness: could a cheap UV filter make a lens seem soft? And is lens softnes a focus thing, or is it more complicated than that?

Here are some samples from this afternoon's session:







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Old Jun 11, 2010, 8:46 AM   #12
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Spent a couple of hours testing the lens to see if I could make it any sharper using autofocus microadjustment. Anything below 0 made the lens even softer, and +2 was noticeably sharper, so I worked through each + increment until I got the sharpest image. Tanks to this focus adjustment, my 10-20mm has gone from being a "mediocre/bad copy" to being very sharp indeed - brilliant!

Click images to view 100% (necessary for comparison)

f/8, 1/125, ISO 100, 10mm


f/8, 1/160, ISO 100, 10mm autofocus microadjustment +10
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Old Aug 12, 2010, 12:50 AM   #13
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You are gonna Love the 50D! Mine Rocks!!
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