Resolution Tests: Tamron AF18-270MM F/3.5-6.3 Di II VC PZD

A few months ago I posted a “first impressions” review of Tamron’s 18-270mm lens. It’s taken me awhile, but here is my promised test of lens resolution. I assessed the lens against a few of the full frame lenses I have in my kit, including the incomparable Nikon 14-24mm, the Canon 24-105mm L, and the Canon 100-400mm L. These are three pro-class lenses, worthy benchmarks for any lens review.

How did the Tamron perform against these three? Surprisingly well, especially in the lower half of its zoom range (optical performance, however, isn’t quite as strong at its longest focal lengths). Which, I guess, isn’t surprising: these new cropped sensor lenses are much easier to design than their full frame counterparts, and tend to have excellent optical characteristics. What is surprising is that Tamron managed to cram some really good optical performance into an all-in-one zoom lens. Chromatic aberration (CA), although fairly well controlled, was apparent (more so than might be expected from a modern coated lens)—but then again, CA is easily fixed in the raw conversion or photo editing process. But I won’t just share my opinions: below I have posted a number of 100% crops so that you may draw your own conclusions.

A quick note on methodology: I used a Canon 5D Mark II full frame camera for all tests. Of course, the Tamron 18-270mm is a cropped sensor lens, so to simulate using a cropped sensor camera, I applied a 1.5x crop to all of the test images. I focused manually using Live View, and for each head-to-head test I focused at the same point. I shot all images using a tripod, with lens image stabilization turned off. Unless otherwise noted, aperture and shutter speed were consistent for all tests. I used f/11 for all tests, except for tests shot at telephoto range, which were set at f/6.3. I did this for several reasons: (1) it made my tests, and this review, a lot more concise, and (2) for most of my nature work with wide t0 normal angle scenes, I almost never go below f/11; when working with wildlife using telephoto focal lengths, on the other hand, I tend to shoot wide open. I did not apply any sharpening to the images—what you see is what you get straight out of the file. I’m sure my methodology is not entirely perfect, but it is certainly sufficient for us to draw meaningful conclusions about the lens and its optical characteristics. Overall, I don’t intend for these tests to be as comprehensive as tests run by professional testers (see, for example, ephotozine.com’s review of the Tamron 18-270mm). Rather, I intend these samples to give context to the subjective evaluations I have made about this lens, and to give readers a good idea of how the lens performs.

Also, as I disclosed in my previous review, Tamron is compensating me for my time spent reviewing, testing, and writing about their lens. That is why I have chosen to present objective lens results in this review, so that you don’t need to take my word on it. Just in case anyone is wondering, I haven’t done any cherry-picking to show only favorable data. Rather, I sought to show results that were representative of my overall tests and conclusions.

Let’s start at the wide end of the range. Here, I matched the Tamron against my Nikon 14-24mm, which is my all-time favorite wide angle lens (I like it so much, I have adapted it to my Canon camera). I have to set aperture manually with my Nikon, without the assistance of a functional aperture scale, so while I estimated f/11 it seems I got something closer to f/8 instead. So, the depth-of-field of the Nikon is a little off (mostly apparent in the background trees), but the crops I present below are within the zone of apparent sharpness for this aperture, and in any event the Nikon is arguably sharpest at f/8 anyway (so it is not a perfect comparison but good enough for the time being). I tested both lenses at 18mm, which is at the widest end of the Tamron’s range. Overall, the Tamron exhibited excellent corner-to-corner sharpness in this test.

Here’s the full scene with the Tamron:

Here’s the first set of crops. First the Tamron 18-270mm @18mm:

Then, the Nikon 14-24mm @18mm:

In my opinion, the Nikon has a very slight advantage, almost imperceptible to the point that I would say these lenses are virtually running neck-and-neck. Here’s a few more crops.

Tamron 18-270mm @18mm:

 

Nikon 14-24mm @18mm:

Tamron 18-270mm @18mm:

Nikon 14-24mm @18mm:

You may notice that the Tamron lens shows some color fringing and chromatic aberration. Here’s another set of crops that shows the CA better. Remember, my depth-of-field for the Nikon is a little off, so these background trees don’t look as sharp as they could.

Tamron 18-270mm @18mm:

Nikon 14-24mm @18mm:

You can definitely see some color fringing in the trees with the Tamron, although it is not too bad. It’s just that the Nikon is better! But then again, the 14-24mm is one of the best lenses ever made, so I’m really impressed that the Tamron holds its own against this world-class lens. Overall, I have to say the Tamron 18-270mm performed very well, even here at the widest extreme of its range.

Next I move to 35mm, and this time I match the Tamron against the Canon 24-105mm L. I find the Tamron’s performance to be a little less even across the frame than at 18mm, but still excellent overall. For some parts of the image, the Canon holds a slight edge over the Tamron, for others parts the Tamron bests the Canon. Here’s the scene as photographed by the Tamron, and then a few 100% crop examples to give you the idea.

Tamron 18-270mm @35mm:

 

Canon 24-105mm @35mm:

Here, at the edge, the Canon and the Tamron seem really close. Below is a crop from an area of the image frame where the Canon outperforms the Tamron.

Tamron 18-270mm @35mm:

Canon 24-105mm @35mm:

But let’s see how they stack up closer to the middle of the image frame. It appears that as we get closer to the center, the Tamron does a better job than the Canon.

Tamron 18-270mm @35mm:

Canon 24-105mm @35mm:

Overall, both lenses do an excellent job, and their performance is fairly close. I wouldn’t hesitate to use the Tamron at this focal range.

At the longest end of the range, 270mm, I did some test shots using the 18-270mm’s widest aperture at this focal length, f/6.3. Here, I tested the Tamron against Canon’s 100-400mm L lens. By the very nature of this test, the Tamron is put at a slight disadvantage, as at 270mm the Tamron is wide-open at f/6.3, whereas the Canon lens, which has a wide aperture of f/5.0 at this length, ends up being stopped down by two-thirds when set to f/6.3. Just a little bit of stopping down can help sharpen a lens, so in a way the test isn’t absolutely fair, but I wanted to test the Tamron’s telephoto performance in a way that I would use the lens with a wildlife subject—wide open. As we can see, at this focal length the Canon L glass is doing a better job. Also, I noticed something curious: either the Tamron or the Canon focal length scale is off. To achieve an equivalent field of view from the Canon lens, I had to zoom out to about 190mm. I don’t have another lens in this range to test against, so I’m not sure which lens is off (and I didn’t notice any significant differences at the other focal lengths I tested). Either way, I decided to match the field of view rather than the numbers.

Tamron 18-270mm @270mm:

Canon 100-400mm @190mm:

As other testers have reported, it appears the 18-270mm isn’t at its strongest at this end of its focal range. Stopping down restores some overall sharpness, which makes this lens perhaps more useful for isolated landscape scenes rather than wildlife. I’ll be testing the lens on some wildlife subjects this weekend, so it will be interesting to see some field results. My overall impression of the Tamron at the 270mm is that its sharpness is adequate (when wide open) to good (when stopped down), but not as good as the excellent sharpness found at other focal lengths.

I’m not the kind of reviewer who will fault a lens for what it’s not supposed to be. The Tamron 18-270mm is not intended to compete with specialized professional zoom lenses such as the Nikon 14-24mm, and Canon’s 24-105mm and 100-400mm L lenses. That said, in terms of optical quality, the Tamron has held its own against these heavyweights, albeit more so at the wider half of its zoom range. What the Tamron 18-270mm lens is intended to be is a lightweight, compact all-in-one zoom for travel, hobbyists, and serious photo enthusiasts alike. From what I’ve seen so far, it handles these jobs with aplomb.

I’ll be doing some final testing of the lens in the field this weekend shooting wildlife subjects. We’ll see how well its auto focus and image stabilization work when dealing with fast moving subjects. Stay tuned!