Fea­tures to look for…

Draw up a wish list for your ideal DX ul­tra-wide zoom

NPhoto - - Test Team -

Com­pared with the nat­u­ral field of hu­man vi­sion, a stan­dard zoom lens gives a blink­ered view.

For sweep­ing land­scapes, you’ll of­ten find that you can’t squeeze ev­ery­thing you want into the frame. The sit­u­a­tion is worse when you’re shoot­ing cramped in­te­ri­ors, where you can lit­er­ally have your back against the wall and still not be able to shoe­horn much into an im­age. The so­lu­tion to the prob­lem is an ul­tra-wide lens.

In this test we’re fo­cus­ing on DX-for­mat lenses (we’ll cover full-frame-friendly FX ones next month), so the 1.5x crop fac­tor needs to be taken into ac­count. A stan­dard 18-55mm kit lens has an ‘ef­fec­tive’ zoom range of 2782.5mm. 50mm has al­ways been con­sid­ered a stan­dard fo­cal length for 35mm film cam­eras and full­frame D-SLRs, with 24mm, 28mm and 35mm be­ing pop­u­lar widean­gle fo­cal lengths, so an 18-55mm DX zoom lens cov­ers the lat­ter two of these op­tions but some­times it doesn’t stretch wide enough. A 10-20mm lens, for ex­am­ple, has an ef­fec­tive zoom range of 15-30mm, ex­pand­ing the max­i­mum an­gle of view to about 110 de­grees, com­pared with about 75 de­grees for an 18-55mm. That might not sound a lot ex­tra but in prac­tice the dif­fer­ence is enor­mous.

DX or don’t bother!

Us­ing an FX lens on a DX cam­era is handy when you want to ex­tend your reach. How­ever, the sit­u­a­tion is re­versed when you’re try­ing to ex­tend your an­gle of view. In most cases FX lenses’ longer fo­cal lengths will fail to give you an ul­tra-wide view­ing an­gle. The full­frame-com­pat­i­ble Sigma 12-24mm is an ex­cep­tion, but you’ll gen­er­ally need to buy an ul­tra-wide lens that’s specif­i­cally de­signed for the DX for­mat. Nikon and Tok­ina both use the ‘DX’ des­ig­na­tion, whereas it’s ‘DC’ for Sigma and ‘Di II’ for Tam­ron. Full-frame lenses from these man­u­fac­tur­ers are clas­si­fied as ‘FX’, ‘DG’ and ‘Di’ re­spec­tively.

When you buy a lens, it’s worth weigh­ing up the ad­van­tages and dis­ad­van­tages of zoom and prime op­tics. Zoom lenses give more ver­sa­til­ity, whereas prime lenses of­ten deliver greater sharp­ness, wider avail­able aper­tures and lower lev­els of dis­tor­tions. Many pho­tog­ra­phers tend to use ul­tra­w­ide lenses at or near their short­est fo­cal length to re­ally make the most of their po­ten­tial. It’s a strange fact, then, that un­til re­cently there were no rec­ti­lin­ear ul­tra-wide prime lenses on the mar­ket for Nikon cam­eras – Samyang’s 10mm f/2.8 ED AS NCS CS prime lens should be on sale by the time this is­sue reaches you.

Rec­ti­lin­ear lenses aim to keep dis­tor­tions to a min­i­mum and, as far as pos­si­ble, give a nat­u­ral per­spec­tive. An­other op­tion is curvi­lin­ear or ‘fish­eye’ lenses. These give an even greater an­gle of view, of­ten as much as 180 de­grees in both hor­i­zon­tal and ver­ti­cal planes, but with ex­treme bar­rel dis­tor­tion. They’re very spe­cialised lenses and com­pletely dif­fer­ent to rec­ti­lin­ear op­tics, so we’re not cov­er­ing them in this group test.

Front el­e­ment

With an in­ter­nal fo­cus sys­tem, the front el­e­ment doesn’t ro­tate dur­ing fo­cus­ing, which is a bonus when us­ing some types of fil­ter. All the lenses in this test have in­ter­nal fo­cus sys­tems.

Fo­cal length

A short min­i­mum fo­cal length is gen­er­ally more im­por­tant than the ex­tent of the zoom range when you’re choos­ing a wide-an­gle lens.

Fo­cus dis­tance scale

A fo­cus dis­tance scale is es­pe­cially use­ful on ul­tra-wide lenses for set­ting the hyper­fo­cal dis­tance (see Jar­gon Buster, be­low).

Lens hood

An­other ad­van­tage of in­ter­nal fo­cus is that a more ef­fec­tive, petal-shaped hood can be used. This type of hood is sup­plied with each of the lenses, apart from the Sigma 8-16mm, which has a petal-shaped hood built in.

Fil­ter thread

Most ul­tra-wide lenses have an at­tach­ment thread for fit­ting screw-in fil­ters, but it’s not al­ways the case, so do check.

Aut­o­fo­cus

All lenses in this test group have ei­ther ring-type ul­tra­sonic aut­o­fo­cus or elec­tric mo­tors built in, so can aut­o­fo­cus on any Nikon D-SLR body.

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