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Some 24 mm comparisons [Nikon/Sigma]
#6
Quote:AiryDiscus, I focused each lens for each aperture and each place (center and left bottom). I don't see the point in refocusing and I don't see the point in refocusing only the Nikon to a different spot - why would I want to focus it between center and corner when I want to have the corner as sharp as possible and f/2 is just not enough DoF?

 

According to the distance measured by the camera, the difference is 0.45 m when focused to the center and 1 m when focused at the corner. Take it with three grains of salt, because some pictures do show 0.84, 0.94 and the "app. 1 m" and the centers differ between 0.45 and 0.47 m. I admit the subject is not the easiest to focus at, even not in LIveView with a loupe. But those are my real life conditions  Smile No OLAF, no MTF chart, no brick-wall, no 17" laptop for tethered shooting. And even LiveView with remote control and mirror up is an exception. Normal conditions to me include phase AF and sometimes questionable shutter speeds.

 

I think the lenses all did quite well and I also think the Sigma prime is a little better in center and much better in the corner because it shows less CA. I'm aware Roger findings are a little different, but then you guys at OLAF control do a great job but not much pictures - no offense meant, of course.

I meant for star field tests.  The "coma" as lenstip mislabels it is largely the result of field curvature.  Changing the focus fixes one part of the problem, stopping down to f/2 fixes most of the other half.
  


Messages In This Thread
Some 24 mm comparisons [Nikon/Sigma] - by JJ_SO - 07-21-2015, 10:12 PM
Some 24 mm comparisons [Nikon/Sigma] - by Scythels - 07-21-2015, 11:41 PM
Some 24 mm comparisons [Nikon/Sigma] - by JJ_SO - 07-22-2015, 05:17 AM
Some 24 mm comparisons [Nikon/Sigma] - by JJ_SO - 07-22-2015, 09:14 AM
Some 24 mm comparisons [Nikon/Sigma] - by Scythels - 07-22-2015, 08:24 PM
Some 24 mm comparisons [Nikon/Sigma] - by JJ_SO - 07-22-2015, 08:42 PM
Some 24 mm comparisons [Nikon/Sigma] - by Scythels - 07-22-2015, 09:09 PM
Some 24 mm comparisons [Nikon/Sigma] - by JJ_SO - 07-22-2015, 11:54 PM
Some 24 mm comparisons [Nikon/Sigma] - by JJ_SO - 07-25-2015, 07:39 AM

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