ON TRIAL

TAM­RON 18-400MM F3.5-6.3 DI II VC HLD ZOOM

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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.

The op­ti­cal con­struc­tion com­prises 16 el­e­ments in 11 groups. Six of the el­e­ments are spe­cial types, in­clud­ing the large-di­am­e­ter front one which is made from op­ti­cal glass with lowdis­per­sion (LD) char­ac­ter­is­tics.

The ‘Vi­bra­tion Com­pen­sa­tion’ im­age sta­bil­i­sa­tion has to work hard on this lens, but still gives 2.5 stops of cor­rec­tion for cam­era shake at 400mm (which, of course, is ef­fec­tively 600mm).

Tam­ron’s HLD – High/Low Torque-Mod­u­lated Drive – en­ables a much more com­pact AF mo­tor with­out sac­ri­fic­ing ei­ther power or torque.

Weather-proof­ing mea­sures in­clude a sub­stan­tial rub­ber gas­ket around the lens mount.

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