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

Started Jul 25, 2014 | Discussions thread
OP citrontokyo Contributing Member • Posts: 812
Re: Buying the DA 18-135? @135mm it could be better, but could also be worse.

OpticsEngineer wrote:

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.

I didn't really have a major point besides the decent center sharpness at 135mm. I don't visit the forum that often, but recently, whenever I do, there always seems to be someone considering buying the 18-135mm but waffling due to doubts over the lens' ability at the longer end.

As you point out, the edges tend to be the main problem at such focal lengths, but I don't shoot too many things at 135mm where they need to be in focus. Bugs, plants, kids, people, unless you are shooting either scenery at a distance or architectural elements then 135mm is not going to give you too many problems with this lens, in my opinion. Process RAW in camera, and you can take care of most aberrations that are not lens softness fairly well.

 citrontokyo's gear list:citrontokyo's gear list
Pentax K-5 Pentax smc DA 55-300mm F4.0-5.8 ED Pentax smc DA 21mm F3.2 AL Limited Pentax smc DA 70mm F2.4 AL Limited Pentax smc FA 43mm F1.9 Limited +4 more
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