ON TRIAL
TAMRON 18-400MM F3.5-6.3 DI II VC HLD ZOOM
There’s no stopping Tamron at the moment, as the lens maker pursues a busy program of product renewal. The new 18-400mm – that’s 27-600mm in the real world – introduces a whole new category of “ultra zooms”.
Tamron strikes out beyond 300mm to take the superzoom even deeper in telephoto territory and create the “ultra-telephoto all-in-one zoom”.
TBelieve it or not, it’s more than 25 years since the term “superzoom” was coined in response to Tamron’s AF28-200mm f3.8-5.6 (a.k.a. the Model 71D) which, when launched in 1992, was the world’s first autofocus zoom with this focal range shoe-horned into a comparatively manageable and affordable lens. However, we can go even further back to Photokina 1984 and the Kiron 28-210mm f4.0-5.6 manual-focus zoom which was the very first lens to offer a super-long focal range and went on sale in early 1985. Soligor launched a 28-200mm f3.9-5.6 model in the same year.
After the success of its first AF 28-200mm, Tamron subsequently introduced several updated versions, delivering various improvements (such as a closer minimum focusing distance) before it moved onto a 28-300mm model. Then, with the development of ‘APS-C’ D-SLRs, it was possible to have an even longer zooming range and, starting in 2005, Tamron produced an 18200mm (equivalent to a 27-300mm in 35mm format terns with a focal length magnification factor of 1.5x), an 18-250mm (27-375mm), an 18270mm (27-405mm) and, in 2015, a 16-300mm (24-450mm).
This represents a steady progression in the zoom ratio of 7.1x up to 18.75x… so are you ready to now step up to 22.2x? Not entirely surprisingly, Tamron has decided that “superzoom” doesn’t quite cover the capabilities of its new 18-400mm f3.5-5.6 model which it is calling an “ultra-telephoto all-inone zoom”.That’s a bit of a mouthful so we’re opting for the much more succinct “ultrazoom” which is essentially a super superzoom.
On a Nikon ‘DX’ D-SLR body, the focal range is equivalent to 27-600mm while on a Canon EF-S mount model, it’s 29-640mm… either of which is pretty dramatic from just one lens. And while it’s not quite as compact as some of the earlier superzoom models from Tamron, it’s no bazooka either. Barrel length is just a shade over 12 centimetres (it’s longer when zoomed out, of course) and the weight is a quite manageable 705 grams which means it won’t overwhelm the typical ‘APS-C’ format D-SLR body. We do need to keep reminding ourselves here that this lens zooms out to the equivalent of 600mm. As a reference, Tamron’s full-35mm format 150-600mm telezoom is over twice as long and weighs a whopping 1285 grams more (that’s nearly 1.2 kilos). Of course, we aren’t quite comparing apples with apples (because on the ‘APS-C’ sensor, the 150-600mm gives you 225-900mm), but in terms of its effective capabilities, the 18-400mm is the zoom lens equivalent of Dr. Who’s famous Tardis… deceptively small on the outside, but able to conquer the tyrannies of distance on the inside.
PUSHING THE BOUNDARIES
Each development of its superzooms has required Tamron to push the boundaries of existing lens technologies, optical designs and manufacturing processes… in some
cases devising its own solutions to the many challenges, especially those related to performance.
Not surprisingly, the 18400mm uses every trick in the book to achieve its combination of capabilities and compactness, including six special elements, a revised distribution of optical power among the individual element groups, a smaller autofocusing drive with a variable torque range, and a new barrel design which distributes its complex movements across three cams. These revisions to the barrel design deal with the sheer physicality of extending from 18mm to 400mm or, more precisely, achieving a zooming ratio of 22.2x which, of course, has never been done before. Additionally, Tamron has been able to weather-seal the barrel – including a substantial rubber gasket around the mount – and install its ‘Vibration Compensation’ (VC) optical image stabilisation (which requires gyros and a dedicated drive). Both extend the lens’s useability in terms of the subject matter and the shooting situation. The stabiliser allows for hand-held shooting in lower light conditions and while the correction for camera shake is only for up to 2.5 stops, this is still better than nothing. The 1/focal length rule for the minimum safe shutter speed is based on the effective focal length which would normally mean 1/600 second, but with the stabiliser can be reduced down to 1/100 second which, in turn, gives you a lot more leeway with apertures and/or ISO settings. Or it means a monopod will suffice instead of a tripod.
SWEET SIXTEEN
The six special elements comprise two aspherical types created via glass moulding, one hybrid aspherical (a spherical core over which optical resin is used to shape the surfaces) and three made from glass with low dispersion characteristics. The aspherical elements correct for distortion and optimise centreto-corner sharpness while the LD types prevent chromatic aberrations.
That the 18-400mm’s total element count is actually only 16 (in 11 groups) gives an idea of just how much work the complex aspherical elements, in particular, are doing. It’s the breakthroughs in the making of aspherical elements – previously a laborious cutting and polishing process – that have enabled these ‘exotic’ zooms to be designed with manageable proportions, better optical performance and affordable prices.
Tamron’s new HLD – High/ Low Torque-Modulated Drive – autofocusing motor is a much more compact unit without sacrificing the power or torque needed to move the focusing group as quickly and accurately as possible.
There are couple of interesting aspects of HLD as used in the 18400mm (it’s also in the 10-24mm ultra-wide), namely that the manual focusing collar actually moves during autofocusing so you need to take care not to inadvertently hinder it. Consequently then, there’s no full-time manual override option during AF. If you’re surmising that this is because the HLD drive is actually physically coupled to the manual focusing collar, you’d be spot on. And, of course, this means the manual focusing is the old-school way… you’re actually moving the focusing group rather than merely sending signals to the AF drive (a.k.a. ‘flyby-wire’). However, the focusing group is still internal so the front element doesn’t rotate during focusing.
The minimum focusing distance is 45 centimetres which is actually quite an achievement in a lens with such a high zooming ratio, and is maintained across the entire focal range. Consequently, at 400mm the maximum magnification ratio is 1:2.9 which isn’t far off onethird lifesize so there’s potential for photographing subjects such as birds or small animals. A supertelephoto focal length isn’t enough by itself for shooting smaller subjects, you also need to be able to focus closer in too.
IN THE HAND
As noted previously, the 18-400mm isn’t excessively big or heavy and so it feels quite at home on a compact or mid-sized D-SLR body. We used the lens on a Nikon D5300 which is one of the smaller ‘APS-C’ format D-SLRs, and the combination felt both comfortable and well-balanced.
The main handling quirk is to avoid getting in the way of the focusing collar because, as just described, it’s directly linked to the AF drive so, if you snag it accidentally, you’ll slow or even stop the autofocusing operation. And this is actually pretty easy to do because the focusing ring is located immediately in front of the zooming collar. You need to consciously adjust your grip so your fingers steer well clear of the focusing control. On the plus side, the focusing ring is much better weighted than any fly-bywire arrangement, enabling finer control with manual focusing. Perhaps because of the wide focal range, the zooming collar has quite a curious action – from 18mm to 50mm it’s pretty smooth, but then it starts to progressively load up quite noticeably so that, until around 200mm, you really need to push quite hard. Once over ‘the hump’, from the 300mm to 400mm it’s at its smoothest and lightest so you need to back off and re-apply a gentler touch. We suspect this has something to do with the shapes of the cam slots and hence the travel of the cam followers – which move the various internal sleeves – so it’s unlikely to go away as the lens is ‘run in’ and you’ll just have to get used to it. There are three switches on the zoom’s barrel for the image stabiliser (on/off), the focusing operation (AF/MF) and a zoom lock.
STABILISATION WAS ONCE GENERALLY ONLY INSTALLED IN LONGER FOCAL LENGTH LENSES, BUT TAMRON PUTS ITS VC UNITS IN MANY SHORTER ZOOMS WHERE, IN REALITY, THEY CAN BE EQUALLY ADVANTAGEOUS WHEN SHOOTING HAND-HELD.
This only operates when the zooming collar is parked at 18mm, preventing the barrel extending while you’re walking along. It’s not needed at any other time because the old scourge of ‘zoom creep’ occurring when a lens is pointed down has long been banished to the history books.
The screwthread filter fitting has a diameter of 72 millimetres so the 18-400mm won’t be especially cheap to equip with the basics (UV, polarizer, etc.), assuming you don’t already have them. As the front surface of the front element is very close to the front rim of the barrel, it’s highly exposed and fitting some sort of filter merely for protection would be a very wise idea. A bayonet-fit hood is supplied with the lens.
PeRfORMANCe
Back in the dark ages, superzooms were better in theory than in practice. Depending on the optical design, the performance at one or the other extreme of the focal range was mostly pretty poor in terms of both sharpness and distortion, making the usable range actually much narrower. Thankfully, this is now longer the case with today’s optical constructions employing complex computer-designed and manufactured lens elements. There are still compromises involved with such a high zooming ratio – undoubtedly one of the reasons Tamron has returned to 18mm at the wideangle end rather than trying for 16mm again – but they are less problematic than before.
Maintaining uniformity of sharpness across such a wide focal range was perhaps the biggest of the engineering challenges facing Tamron with this lens, but it has to be said the results here are pretty impressive. The old 18-270mm model – which actually isn’t all that long ago – wasn’t especially sharp, but this 18-400mm is in a completely different league. Images look nicely crisp at any focal length with well-defined detailing and good contrast. Interestingly, the centre-to-corner sharpness is at its best at 18mm, even when shooting wide-open at f3.5. It stays pretty uniform across the aperture range until f16 and f22 when diffraction starts to take effect. Overall sharpness remains very good up to about 200mm, but at the longest focal lengths, there’s noticeable softening in the corners unless you stop down to f8.0 or f11 which, of course, will mean using a slower shutter speed unless you bump up the ISO (with the potential to also compromise image sharpness depending on the camera) or resort to using a tripod.
Still on the subject of sharpness, softening caused by camera shake will become an issue if you don’t keep a sharp eye on the shutter speed when shooting in either the program or aperture-priority auto control modes. Zoom from 18mm to 400mm and it could slow from, say, 1/200 second all the way down to 1/25 second – as it did in one of our tests – not just because of the slower lens speed (possibly down to f40 at 400mm), but because the overall reflectance can drop quite dramatically. The image stabilisation won’t help you at 400mm (which is really 600mm) and 1/25 second. Our advice would be to shoot in the shutterpriority mode so you can manually control the shutter speed or, if possible, set the Auto ISO not to select shutter speeds slower than what’s safe with the IS operation. Because the 18-400mm is so comparatively compact, it’s easy to forget that there’s effectively 600mm on tap and therefore even the tiniest amount of camera shake will result in quite significant blurring.
Distortion is mostly well controlled with some noticeable barrel-type bending at the 18mm focal length which gradually becomes pincushion distortion at 50mm, but then – pretty remarkably – reduces progressively across the telephoto focal lengths to become virtually negligible at 400mm.
Also remarkable are the near absence of any flare or ghosting – a testimony to the effectiveness of Tamron’s ‘BBAR’ anti-reflection multi-coating – even at the longer focal lengths when the lens hood actually isn’t doing much at all. Vignetting is noticeable across the focal range, but most pronounced at the wide-angle end and easily eliminated by stopping down. Some chromatic aberration is evident along high-contrast edges at the frame’s extremities, especially at 400mm, but it’s not ever excessive and is easily dealt with post-camera. While the zoom’s diaphragm has seven blades so the aperture opening isn’t quite as fully rounded as it would be with nine or more, the out-of-focus effects are still smooth so backgrounds can be nicely softened when using selective focusing with subjects such as portraiture.
All this represents a very solid optical performance for a superzoom… sorry, ultrazoom… with only the corner sharpness at 400mm not quite up to the high standards set by the rest of the lens. It’s very likely you’ll be buying this lens exactly so you can shoot at 400mm and utilise the effective power of 600mm, but don’t be put off, the results are still excellent even if you might have to juggle with the apertures and shutter speeds.
THe VeRDiCT
Superzooms have had mixed press in the past, but they have been steadily improving on all levels over time even if you’ll still occasionally see the “consumer grade” put-down in a review. While it may have once been true that these lenses were mostly bought by people who didn’t want to continually change lenses, the potential versatility is now being recognised by a wider crosssection of D-SLRs users.
Its build quality, weatherproofing, optical performance, AF operation and close focusing capabilities all put Tamron’s 18400mm firmly in the “enthusiast grade” category. The obvious application is travel photography when carrying just one lens is increasingly advantageous, but it’s also an affordable option for everything from landscapes and portraits to sports and wildlife… and in a wide variety of shooting situations. There are still some performance-related compromises, of course, but overall this lens is more super than any superzoom we’ve seen so far. Super!
MAInTAInIng unIforMITy of ShArpneSS ACroSS SuCh A wIde foCAL rAnge wAS perhApS The bIggeST of The engIneerIng ChALLengeS fACIng TAMron wITh ThIS LenS, buT IT hAS To be SAId The reSuLTS here Are preTTy IMpreSSIVe.