I have been wondering about the sharpness of the Tamron 18-270 VC II PZD. I own it for 1,5 year and feel it can not render sharp images, or sharp enough images, despite that I've sent it to Tamron representative for service in its early days. That is the case when shooting landscape. Of course, I love its versatility, but the image result is below of what I desire (previously, I read good and positive reviews on this exotic lens, mostly hands-on review and the sample images were mostly people or portrait).

So I decide to compare it with my 18-70 Nikkor that I know quite well. The 18-70 is sharp enough, that I pleased with the result after using it for years. For sure, the Tamron is an all-around zoom; not a pro lens, so what can we expect for such a lens? But the softness really disturbing if not make me nervous in the field. And 18-70 is not a pro zoom either. So I ran a simple test to compare how sharp or how soft each other is. Here we go...

Camera used in this test is D7000, performed at ISO 320. No noise reduction, sharpening, no editing except slight exposure adjustment for 18-70 shot.

18-70 @ 70 mm,  its longest end @ f/9.0.

Nikon 18-70 AFS @ 70 mm f/9

Now the Tamron @ 100 mm @ f/10.0

Tamron 18-270 VC II @100 mm f/10 Image from the Tamron is clearly softer and of a lower contrast. Take a look at the column on the left.

Now we would think we don't do justice with the Tamron with f/10, so let's use f/13 instead, equivalent of two stops from widest aperture, the same with 18-70:

Tamron 18-270 VC II @100 mm f/13 It turns out that @ f/13 the image is softer than @ f/10. Diffraction plays a nasty role here. So you can't stopped down too much with this lens.

Now lets take a closer look.

Crop from the same shot of 18-70 (first photo above):

crop 18-70 from previous photo

And 18-270:

crop 18-270 from previous photo

VERDICT:

Tamron 18-270 VC II PDZ performance is clearly below the Nikon 18-70 AFS, either in the border or the centre in terms of contrast and resolution, though the border is worse. This confirm of what I feel about this all around zoom lens.

Note: images used in this test is a representative sample of population of the test result. Since I use my own copy of lenses, I don't know and cannot tell if other copy will produce the same result. This apply to most test, since they usually test only one copy. To prove this, my 18-70 is a good one, better than the mass. Every photographer who use it surprised with the quality come from this cheap lens, different from what they own. Nevertheles, anyone considering buying this all you can do lens should be aware of the trade-off between versatility and quality.