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Old Oct 17, 2005, 11:55 PM   #1
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I did a sharpness test between my Sigma 12-24mm EX DG vsSigma 18-50mm EX DC. All photos were taken with a Canon 20D mounted on a tripod using a Sigma EF-500 DG Super flash, camera set at f7.1, ISO100, center focus. Focus was set on the blue cereal box's nutrition info at the "Calories" and "Total Fat" info. Used a remote switch to trigger the shots. Subjects were about 11 inches from the camera.

Full size photos can bedownloaded from http://www.myitlab.com/deals/data/upimages/Sigma/

Sigma 12-24 @ 18mm


Sigma 18-50 @ 18mm




Sigma 12-24 @ 20mm


Sigma 18-50 @ 20mm




Sigma 12-24 @ 24mm


Sigma 18-50 @ 24mm

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Old Oct 18, 2005, 2:37 AM   #2
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The Sigma 18-50 @ 24mm appears to be quite a bit more clear, at least to my eye.
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Old Oct 18, 2005, 3:10 PM   #3
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Ok, I cropped the nutritional values only for both lenses...As I'd expected, the 18-50 EX DC is sharper than the 12-24 EX DG...any opinions on the sharpness of the 12-24 EX DG? I guess I'm just paranoid with this lens...just want to make sure it's as sharp as it can be...or if not, I may need to send it to Sigma for adjustment.
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Old Oct 18, 2005, 9:28 PM   #4
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Your 12-24 EX looks fine...

The 18-50 may be more contrasty, but the 12-24 in your samples focus further back than the front of the cereal box - See the books on top in the background (and the yellow flower on left) of the 12-24, they are sharper than on the 18-50, which could be caused by the camera since a lens does not focus by itself but is controlled by the camera - The AF plane may move back and forth a little bit (plus the high-precision sensor is not enable below f/2.8 for the 12-24 EX)

In normal landscape use (ie larger distance than 11") these minor focusing differences are not going to be noticeable... :-)
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Old Oct 18, 2005, 10:46 PM   #5
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NHL wrote:
Quote:
Your 12-24 EX looks fine...

The 18-50 may be more contrasty, but the 12-24 in your samples focus further back than the front of the cereal box - See the books on top in the background (and the yellow flower on left) of the 12-24, they are sharper than on the 18-50, which could be caused by the camera since a lens does not focus by itself but is controlled by the camera - The AF plane may move back and forth a little bit (plus the high-precision sensor is not enable below f/2.8 for the 12-24 EX)

In normal landscape use (ie larger distance than 11") these minor focusing differences are not going to be noticeable... :-)

Ok, I feel a lot better now reading your reply. Thanks!
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