Buying the DA 18-135? @135mm it could be better, but could also be worse.

Started Jul 25, 2014 | Discussions thread
OpticsEngineer Veteran Member • Posts: 5,853
Re: Buying the DA 18-135? @135mm it could be better, but could also be worse.

I was not sure what your point was.  But it revived my curiosity about the 18-135.  So this afternoon I shot a series of test shots with my K3 of a target board filling the the center 30% of the lens at 18, 24, 35, 50, 70, 100 and 135 mm.  I found the center sharpness stays pretty much constant throughout the zoom range.  I also did the same thing with my Nikon D7100+Nikon-18-140 and Sony A65+Sony-18-135.   My Pentax did a bit better than the Nikon and Sony on center sharpness.

A few weeks ago, with target boards filling the entire field of view of the camera, I found that for edge and corner sharpness, the Nikon 18-140 does a lot a better than my Pentax 18-135.

Sony 18-135 is about the same as the Pentax 18-135 in terms of there being  a fall of in resolution at the edges.  I am always a bit puzzled why the Sony 18-135 does not gather the same criticisms as the Pentax 18-135 considering how similar they are in terms of resolution fall at the edges.    It is hard to compare the Sony setup to the Nikon and Pentax though.   The Sony has an AA filter whereas the K3 and D7100 do not.  The AA filter, unsurprisingly, really reduces the resolution when you pixel peep.   But for that you do not get the moire patterns that occur with the test charts.

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