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Sigma 18-300mm on K50 and K70

Started Dec 12, 2016 | Discussions thread
OpticsEngineer Veteran Member • Posts: 7,839
Sigma 18-300mm vs Pentax 18-270 on K70

Here a couple of JPEG comparison test shots on a K70 of the 18-300 and 18-270.   Post-it note in the middle identifies which shot goes with each lens.

K70 set to contrast +2 and sharpening +2.   Lens corrections turned on are lateral chromatic and diffraction.  (vignetting and distortion off)   Handheld, daylight, image stabilization on.  My goal here is to test the 18-300 lens the way I will use it and sort out if  I want to keep it or return it.  (it is a keeper)

The Pentax 18-270 has quite a bit of chromatic aberration near full zoom but the camera corrects for it.   I believe the Sigma does not benefit from in camera chromatic correction since it is a third party lens.  So I was curious if that was a problem or if Sigma done a good job correcting chromatic aberration so it was still pretty good.

What I see in practice is the Sigma is pretty much the equal of the Pentax.

Besides these shots there are a couple more in my gallery.

There are some over sharpening artifacts in the images.  If I were doing it over I would cut back on the sharpening.

18-300

18-270

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