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Design

The 18-270mm is typical in design and build for a recent Tamron lens. The barrel is made of fairly lightweight plastic, and subjectively the construction doesn't feel quite as solid as its Sigma counterpart (although it's not obviously 'bad'). The lens uses a 'double trombone' design to extend to its longest setting, and as we'd expect of a lens at this price, the mount is metal.

The zoom ring is relatively stiff, and has a somewhat uneven feel, with noticeably higher resistance to rotation around the 50mm marking. The focus ring is smooth, but a little loose in operation. The overall impression is of a lens that's been built to a price, but sensibly so.

Two large, positive switches on the side of the barrel control the autofocus and image stabilization mechanisms, and are well-placed for operation by your left thumb while holding the camera in the normal shooting position. Meanwhile a sliding switch on the other side of the zoom ring locks it at the 18mm position for transport - this is a bit less easy to reach in a hurry.

Zoom action / zoom creep

Superzoom lenses, with their long extensions and heavy front elements, tend to suffer from two related ergonomic issues - uneven zoom ring actions, and 'zoom creep', i.e. a tendency to extend under their own weight when carried around. This tends to be most problematic if you habitually carry the camera with the lens pointing downwards, either in-hand or using a sling-type strap.

The 18-270mm, as mentioned above, has a slightly uneven zoom action across the range. Our review sample was quite resistant to zoom creep when retracted to the 18mm position, but quickly extended under its own weight when pointed downwards at other settings. Like most lenses of its type it does have a switch to lock it at the 18mm position, at least.

Compared to Sigma 18-250mm f/3.5-5.6 DC Macro OS HSM

Here's the Tamron 18-270mm PZD alongside it's nearest rival, the Sigma 18-250mm F3.5-6.3 DC Macro OS HSM, both in Canon mount. The two lenses are practically identical in size when retracted to the 18mm position. They also have very similar control layouts, with side-mounted switches to control autofocus and image stabilization, and a lock switch on the zoom ring. Both feature built-in optical stabilization too, but while the Tamron has a longer zoom range, the Sigma can focus closer. This is illustrated below:

Tamron 18-270mm F3.5-6.3 PZD
Sigma 18-250mm f/3.5-6.3 Macro
270mm, distant subject 250mm, distant subject
Macro: Closest focus = 43cm Macro: Closest focus = 29cm

On the camera

Even on a small entry-level SLR such as the Canon EOS 650D shown here, the Tamron 18-270mm F3.6-6.3 PZD feels nicely balanced, which isn't something that can be said of all superzoom lenses. It's notably smaller than either the Canon or Nikon 18-200mm F3.5-5.6 superzooms, and much the same size as the Sony 18-250mm F3.5-6.3 and Pentax 18-270mm F3.5-6.3 models. It's relatively light in weight too, and won't put too much strain on your shoulder if you carry it around on the camera all day.

Flash shadowing

One problem often seen with superzooms, especially on smaller SLR bodies, is that the lens will block the built-in flash at wideangle resulting in a shadow in the lower center of the image. We tested the Tamron on a couple of Canon bodies, including the entry-level EOS 650D, and never really saw any semblance of shadowing, even at 18mm and focus distances close to the minimum - a distinct advantage of the compact barrel. Do note, though, that if you shoot at wideangle with the hood attached you'll see considerable shadowing.

Based on our previous experience with such lenses, however, we would expect the 18-270mm to show a degree of shadowing with some of the smallest entry-level DSLRs, particularly older models on which the flash unit doesn't lift quite so high above the lens axis. But again its compact size means the problem should be minimal.

Autofocus

The 18-270mm uses Tamron's Piezo Drive (PZD) motor for autofocus. When shooting with the optical viewfinder our Canon mount sample was near-silent in use, and decisive even at full telephoto. But it's not the fastest around, and noticeably slower than the Sigma 18-250mm HSM used on the same (Canon) body. As always, though, it must be noted that focus speed and accuracy is dependent upon a number of variables, including the camera body used, subject contrast, and light levels.

Switch from the optical viewfinder to live view, though, and the story changes. Focusing slows right down (although the exact speed is highly dependent on the camera used), and if you refocus during movie recording the clicking of the AF motor will be audible on your soundtrack as the camera fine-tunes focus. It's not obviously worse than the majority of SLR lenses in this respect; it just can't match the purpose-designed lenses for mirrorless camera systems.

Dependence of effective focal length on focus distance

This lens's angle of view widens dramatically on focusing from infinity to 0.49m, especially at the telephoto end. This is a common trait with superzooms, but at a focus distance of 2m the 270mm telephoto end has an effective focal length that's closer to 200mm. In context, it is worth bearing in mind that long telephotos generally tend to used more for distant subjects, in which case the lens naturally behaves as a 'true' 270mm; and at short distances you merely have to move a little bit closer to compensate.

Lens body elements

The lens comes in Canon, Nikon and Sony versions; our review sample was in the Canon EF mount.

The Sony version of the lens doesn't have the VC mechanism (and therefore drops these initials from its name). Tamron doesn't make a Pentax mount version, unfortunately.
The filter thread is 62mm - unusually (and economically) small for a superzoom. It does not rotate on autofocusing, which makes for easier use of filters like polarisers.
The DA18 bayonet-mount hood is provided as standard, and clicks positively into place on the front of the lens. It features ribbed moldings on the inside to minimize reflections of stray light into the lens. The plastic is slightly flimsy-feeling, and doesn't feel like it would survive too much abuse.

A white dot on the outside of the hood aids alignment for mounting, and the hood reverses neatly for storage.
The zoom ring has a 29mm wide rubber grip, and rotates 70 degrees clockwise from wide to telephoto (the same way as Nikon, Pentax and Sony lenses, but opposite to Canon). The action is slightly stiff and uneven, with most resistance around the 50mm setting.
A small switch on the side of the barrel locks the zoom at 18mm, preventing the lens from extending under its own length when you're carrying it around. This is especially welcome if you like to use a sling-type strap to carry your camera.
The focus ring has a 7mm-wide grip, and rotates just 40 degrees anti-clockwise from infinity to 0.49m, matching Pentax and Nikon lenses but opposite to those from Canon and Sony. It's smooth but a little loose in feel, and the limited travel can make precise manual focus tricky.

A basic distance scale is marked in feet and meters. The focus ring rotates during autofocus.
Two chunky, positive switches on the side of the lens barrel set the focus and image stabilization modes. You can't adjust focus manually when the lens is set to AF (or at least, you shouldn't try).

Reported aperture vs focal length

Here we show the maximum and minimum apertures reported by the camera at the marked focal lengths.

Focal length 18mm 35mm 50mm 70mm 100mm 200mm 270mm
Max aperture
F3.5
F4.5
F5.0
F5.6
F5.6
F6.3
F6.3
Min aperture
F22
F29
F29
F32
F36
F40
F40

The 18-270mm PZD offers a similar maximum aperture progression to other superzooms, including its predecessor and the Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM. It's also similar to the Nikon AF-S Nikkor 18-300mm F3.5-5.6G ED VR up to about 100mm - the main difference is that the (much larger) Nikon then maintains F5.6 right out to full telephoto.

Tamron also allows you to stop down to extremely small apertures towards the long end of the zoom, but we really wouldn't recommend using these due to the blurring effects of diffraction.

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Comments

Total comments: 3
Coudy

I own this lens together with Canon 70D, recently I have obtained for tests tele photo kit lens Canon EF-S 55-250 4-5.6 IS II. What puzzles me is that in max focal length of both camera (Canon 250mm and Tamron 270mm) Canon has managed to get closer to the subject, actually a lot. If I am not missing some EF-S to EF conversion and all number written on those lens are true (Canon 70D with 1.6 crop factor) I don't understand where is the problem. I have created jpg file to demonstrate maximum focal lengths of each lens (also a Canon EF 75-300 4-5.6 III) and Tamron just doesn't get anywhere near to Canon lenses.
http://www.coudy.us/Canon_70D_4x_telephoto_lens.jpg

Anyone can explain this?

1 upvote
Tamalero

Isnt the issue related to lens focus"breathing"?

0 upvotes
Coudy

it is, I figured it out with the help of dpreview members a while ago. Didnt know about focus breathing phenomen before and therefore felt being cheated on. I still do feel like lenses producing companies are cheating, but I guess in some theoretical circumstances they meet advertised parameters.

Comment edited 2 minutes after posting
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Total comments: 3