Photo packs have come a long way in the past decade, especially those that are targeted toward outdoor and adventure photographers. Alaska-based adventure photographer Dan Bailey takes a closer look...
The AF 18-270mm f/3.5-6.3 Di II VC LD ASPHERICAL (IF) MACROPZD (to give it its full title) is Tamron’s widest focal range zoom (15x) and a surprisingly small lens (3.9" long and only 15.9 oz) for such a wide range zoom. It’s approximately the same size as the Canon EF-S 17-85/3.5-5.6 IS USM). It features Tamron’s VC (vibration compensation) image stabilization system and it uses both LD (low dispersion) and aspherical elements to maximize image quality. The “MACRO” designation shouldn’t be taken too seriously though. The lens is fairly close focusing (19") but maximum magnification is 0.26x (1/4 life size) and it doesn’t use any special optical corrections when close focused.
The “Di II” designation indicates that it is designed for use on crop sensor DSLRs. Although it can be physically mounted on a full frame DSLR, the image circle is not designed to cover the whole frame and so results in strong vignetting out near the edges of a full 35mm frame.
Construction quality seems pretty good. The lens appears to be all plastic but it seems quite solid and there’s little barrel wobble, even when fully extended. There’s a wide rubberized ring for zoom control and a narrower ring for focus just in front of it. The focus ring spins during autofocus, so you need to keep your fingers away from it. There is a distance scale and to go from infinity to close focus requires only turning the focus ring by about 45 degrees, so manual focus action is fairly fast (but precise manual focus may be difficult).
The autofocus motor is Tamron’s new “Piezo Drive” (PZD) which seems to be a system somewhat similar to Canon’s micro USM. It uses a small piezoelectric (ultrasonic) motor which drives the focusing mechanism via a gear system. This type of motor is small. lightweight and quiet, but it’s not as fast or versatile as a ring type ultrasonic motor (Canon’s USM, Tamron’s USD). It does not allow for full time manual focus. To use this lens in manual focus mode, the AF.MF switch on the barrel must be moved to the MF position.
Note that there is an earlier version of this lens which doesn’t use a PZD motor. The new lens is 24% shorter and 18% lighter and uses a different optical design.
Where to Buy
Photo.net’s partners have the Tamron 18-270 VC PZD lens available. Their prices are fair and you help to support photo.net.
The 18-270 PZD will also be available in a version for Sony DSLRs. This version will not have image stabilization built into the lens since Sony DSLRs have an sensor shift stabilization built into the camera bodies.
Tamron 18-270/3.5-6.3 Di II VC PZD Specifications
Angle of View (diagonal)
75° 33 – 5° 55
16 elements in 13 groups
Minimum Focus Distance
Max. Magnification Ratio
1 : 3.8 (at f=270mm : MFD 0.49m)
88mm (3.5 in)
74.4mm (2.9 in)
450g (15.9 oz)
Flower shaped lens hood
Canon, Nikon, Sony
The Tamron 18-270/3.5-6.3 Di II VC PZD has a 15x zoom range from 18mm to 270mm, but it’s important to remember that these focal lengths are measured with the lens focused at infinity. Just about every close focusing, internal focus, super wide-range zoom changes in focal length when close focused. I guess it’s one way in which such lenses can be small but yet have a small minimum focus distance.
For example the Tamron 18-270/3.5-6.3 Di II VC PZD will focus as close as 0.49m (19.3") when set to 270mm. In comparison the Tamron 70-300/4-5.6 Di VC USD lens only focus down to 1.5m (4.9ft). However despite the much closer focusing ability, the 18-270 yields a maximum magnification at 270mm of 1:3.8 (0.26x), while the 70-300 yields almost the same magnification of 1:4 (0.25x) at 300mm, despite being three times further away from the subject.
I made some approximate measurements of focal length at various focusing distances. These were made by comparing magnification of the 18-270 at the marked 270mm focal length setting and the 70-300 at 300mm and assuming that the 70-300 doesn’t significantly change focal length. On that basis I found the following effective focal lengths as a function of distance:
Infinity – 268mm
50ft – 235mm
20ft – 196mm
10ft – 166mm
5ft – 130mm
[Note that the 70-300 may itself change focal length slightly when close focused, so these numbers should be look at as relative, not absolute measurements]
Now this should come as no surprise to anyone familiar with this type of lens. It’s very common and happens with lenses made by all manufacturers. It’s not a defect and I don’t think there’s any real intent to deliberately deceive the buyer, but it’s not commonly something the lens manufacturers talk about. This results in forum postings from some surprised users along the lines of “My 300mm lens is only 175mm. What’s wrong?” The answer is that nothing is wrong. At close focus distances that the way that small, internal focus, wide-range zooms work.
That fact that most users never notice the effect is an indication that it isn’t that big a deal for most people. What matters to most is that they can adjust the zoom to get the framing they want and that, of course, is still the case – unless you are zoomed out all the way. It’s just that the magnification at the 270mm long end of the zoom range at closer focus distances will be somewhat lower than it would be if you were using a 270mm prime lens or a larger zoom with a less extreme range and longer minimum focus distance.
For another example of a wide-range zoom that changes focal length, see my review of the Sigma 50-500 OS 10x zoom (http://photo.net/equipment/sigma/50-500os/).
Focal lengths (at infinity focus) are marked at 18, 35, 50, 70, 100, 200 and 270mm. Zoom creep was observed with the lens pointed vertically upwards and the zoom set to 150mm or less. In that situation the zoom setting quickly changes to about 24mm. Similarly with the lens pointing downwards and the zoom set over 24mm, the zoom will quickly creep to around 150mm. When set at the extreme focal lengths (18mm or 270mm), the zoom action is stiff enough to prevent any creep. I should add that I only tested one lens. Other samples may be different, though I have seen a number of user reports which commented on the same issue. There is a zoom lock at 18mm which locks the lens in its shortest position and prevents it from accidentally extending while it’s being carried
The maximum aperture ranges from f/3.5 at 18mm to f/6.3 at 270mm. Technically, according to Canon, f/6.3 should be too slow for autofocus on a Canon EOSAPS-C body like the EOS 60D and 7D, but in fact the lens had no trouble with AF on either body. F/6.3 is quite normal for the long end of telephoto zooms made by 3rd party lens makers. They all play some “tricks” on the camera body to convince it to autofocus. Canon lenses have a hard limit at f/5.6, beyond which the body will not even attempt focus.
This table shows the maximum aperture in different focal length ranges (according to an EOS 60D set to show aperture in 1/3 stop steps).
As might be expected from a wide range zoom, there is some distortion, especially at the focal length extremes. At 18mm I measured about 4% barrel distortion which quickly changes over to pincushion distortion as the lens is zoomed out. At 100mm I measured 2.3% pincushion distortion and at 270mm I measured 1.7% pincushion distortion. Minimum distortion is around the 35mm focal length setting.
These levels of distortion would be noticeable on subjects expected to be rectangular (e.g. architecture, posters, doorways), though distortion is one of the easier aberrations to digitally correct. It’s a price you pay for such an extreme zoom range in such a small lens.
Vignetting (dark corners) is most evident wide open (f/3.5) at 18mm where I measured the extreme corners about 1.5 EV darker then the center of the image. Things improve as the lens is zoomed out to 50mm where vignetting is lowest, about 0.5EV wide open, and then vignetting gets stronger again as the lens is zoomed out to 270mm where I measured about 1.25EV at full aperture (f/6.3). Stopping down can help a little, especially at the telephoto end of the range, but at 18mm the corners of the image are noticeably darker (by about 0.7 EV) even at f11. Luckily vignetting is fairly easy to correct digitally. It would most likely to be noticed shooting landscapes at 18mm, where darkened sky in the upper image corners might be an issue.
Chromatic aberration is worst at the focal length extremes and lowest around 50mm. It’s particularly noticeable in the image corners at 18mm and 270mm.
At the telephoto end of the focal length range and in the center of the frame, image quality is good even at full aperture (f/6.3). It sharpens up a little when stopped down, but I wouldn’t be hesitant to use this lens wide open if my main subject was in the center part of the frame. There’s more of a problem at the edges and corners of the frame, where corner sharpness is lower and is also compromised by fairly noticeable chromatic aberration.
To test performance at 270mm I took some shots of the moon with the Tamron 18-270 and compared them with similar shots taken with the Tamron 70-300mm f/4-5.6 Di VC for Canon, (compare prices) (review), also set to 270mm. The 70-300vc has full frame coverage, but is significantly larger than the 18-270vc and of course it has a much smaller zoom range (4.3x vs. 15x). However, it is cheaper and as you can see, quite a lot better in the corners of a crop sensor image. This is as expected. To get the higher image quality in the corners you have to be prepared to carry around a larger lens with a more restricted zoom and and so swap it off the camera if you want to shoot wideangle shots.
At 18mm center image quality is reasonably good, comparable to lenses like the Canon EF-S 17-85mm f/4-5.6 IS USM, (compare prices), however in the corners the image is noticeably soft and shows noticeable chromatic aberration. Stopping down may help a little, but doesn’t significantly improve the image quality in the corners.
In the mid range image quality is again pretty good in the center of the frame and holds up a little better in the corners. Again, the image is comparable to that from the Canon 17-85/3.5-5.6 IS USM in the center of the frame and in the corners, but the Tamron shows lower levels of chromatic aberration.
The Tamron VC (vibration control) system is very similar to that of Canon’s IS (image stabilization). Both use gyro sensors to measure lens movement and both move a group of elements to compensate. In informal testing I’d estimate the effectiveness of the Tamron VC system on the 18-270mm zoom at somewhere around 3 stops at 270mm. Visually (through the viewfinder) the action seems a little less smooth than that of Canon’s lenses, but in testing it seemed equally effective at minimizing image blur.
If you want just one small, light lens that will do everything most photographers want to do, from shooting landscapes to travel photography, portraits, sports and wildlife, the Tamron 18-270 is a good choice. It’s pretty sharp in the center of the field, AF is accurate (if not blazingly fast), the VC image stabilization works well and it’s very compact. It’s also available in a Nikon mount and there is a non-stabilized version for Sony DSLRs.
The price you pay for the size and versatility comes in two varieties. First, it’s not an inexpensive lens, and second you have to put up with some optical consequences such as distortion, close focus focal length reduction and less than perfect corner image quality. None of these are probably serious enough to put off those users who value convenience over pure optical quality, and that’s the market at which this lens is aimed, and in which it should sell quite well.
If you hate changing lenses and want something small and light, yet very versatile and capable, the Tamron 18-270/3.5-6.3 Di II VC PZD should certainly be high on your list of possible choices.
Where to Buy
Photo.net’s partners have the Tamron 18-270 Di II VC PZD lens available. Their prices are fair and you help to support photo.net.
Canon EOS 60D + Tamron 18-270/3.5-6.3 VC @ 76mm f/6.3. In this focal length range image quality is excellent. Distortion is fairly low, there’s no visible chromatic aberration and vignetting is slight (especially when stopped down a stop). Overall a high quality image.
Canon EOS 60D + Tamron 18-270/3.5-6.3 VC @ 18mm f/3.5. Although testing shows that distortion is high (around 4% barrrel) and there is vignetting in the image corners (1.7EV), you wouldn’t immediately see either problem in this shot unless you really looked for it. Yes, the upper corners of the image are a little dark, but not to the extent that it’s a serious problem.
Canon EOS 60D + Tamron 18-270/3.5-6.3 VC @ 18mm and 270mm. Just an example showing the extreme, 15x, zoom range of this lens, an indication of its versatility and usefulness for a wide range of subjects.
Canon EOS 60D + Tamron 18-270/3.5-6.3 VC @ 42mm, 1/250s, f/4.5, ISO 400. This shot taken in the “normal” focal length range shows good sharpness and contrast across the whole APS-C frame, even wide open at f4.5. Distortion and chromatic aberration are both well controlled at this focal length.