Zoom zoom!

Matthew Richards takes a look at eight fast tele­photo zooms to dis­cover which has the best go-faster cre­den­tials

NPhoto - - Gear Zone -

There are some good ‘bud­get’ tele­photo zoom lenses on the mar­ket. Nikon’s AF-S 70-300mm f/4.5-5.6G VR (£520/$500) is the best in class, while the Tam­ron SP 70-300mm f/4-5.6 Di VC USD (£300/$450) is a top bar­gain buy. But one thing that all so-called bud­get tele-zooms tend to share is a vari­able aper­ture rat­ing that shrinks as you ex­tend through the zoom range, typ­i­cally down to f/5.6 at the long end.

Ex­pert and pro­fes­sional pho­tog­ra­phers gen­er­ally pre­fer ‘con­stant-aper­ture’ zoom lenses wher­ever pos­si­ble and, in the case of tele­photo lenses, are often will­ing to sac­ri­fice greater tele­photo reach in or­der to get it. The favoured choice is there­fore a 70-200mm zoom, with a faster f/2.8 aper­ture rat­ing. At the long end of the (al­beit slightly shorter) zoom range, they’re two stops faster than f/5.6.

Even at a di­rectly equiv­a­lent 200mm zoom set­ting, most 70-300mm lenses are still nearly two stops slower.

Bonuses of the wider aper­ture rat­ing are two-fold. First, you can gain faster shut­ter speeds with­out the need to ramp up the ISO. This is ideal for freez­ing the ac­tion in sports and wildlife pho­tog­ra­phy, in any­thing other than bright sun­light. Sec­ond, a wider aper­ture pro­vides a tighter depth of field, en­abling you to throw the back­ground fur­ther out of fo­cus and re­ally iso­late your sub­ject. For this rea­son, fast tele­photo lenses are often favoured for por­trai­ture at wed­dings and other events, where light lev­els can be quite low, and where you need the ver­sa­til­ity of a zoom lens.

A less-ob­vi­ous ad­van­tage of con­stant-aper­ture zoom lenses is that, when you’re shoot­ing in man­ual mode, you can set the lens to its widest avail­able aper­ture and be sure that it’s not go­ing to change when you ex­tend the zoom set­ting.

The ma­jor­ity of lenses in this month’s Big Test have an f/2.8 aper­ture rat­ing. This means that you can fit a 1.4x tele­con­verter to gain nearly a 300mm fo­cal length (280mm to be pre­cise) and still en­joy a rel­a­tively fast f/4 widest aper­ture. You can go fur­ther still, with a 2x tele­con­verter that de­liv­ers a su­per-tele­photo 400mm fo­cal length, while still only drop­ping to an f/5.6 aper­ture rat­ing, main­tain­ing full aut­o­fo­cus com­pat­i­bil­ity with any Nikon DSLR. We should point out, that while Tam­ron usu­ally sug­gests the use of Kenko tele­con­vert­ers with its lenses, these aren’t com­pat­i­ble with the 70-200mm VC USD lens on test. Tam­ron’s brand-new 70-200mm G2 (sec­ond-gen­er­a­tion) lens is com­pat­i­ble with Tam­ron’s own lat­est tele­con­vert­ers, but the Nikon-fit edi­tion wasn’t avail­able for re­view by the time we went to press.

Han­dling is re­fined in all of the lenses in our test group, com­pared with vari­able-aper­ture lenses. With fully in­ter­nal zoom and fo­cus mech­a­nisms, the phys­i­cal length of the lens re­mains fixed through­out the en­tire zoom and fo­cus ranges. (You’ll no­tice that with a 70-300mm bud­get zoom, for ex­am­ple, the phys­i­cal length nearly dou­bles as you sweep to the long­est end of the zoom range.) Up­mar­ket build qual­ity also con­fers a more ro­bust and hard-wear­ing con­struc­tion, as well as smooth and pre­cise oper­a­tion of zoom and fo­cus rings. All in all, a fast tele­photo zoom is usu­ally a sig­nif­i­cant step up the qual­ity lad­der, in terms of build, han­dling and al­limpor­tant im­age qual­ity.

A wider aper­ture pro­vides a tighter depth of field, en­abling you to throw the back­ground fur­ther out of fo­cus and re­ally iso­late your sub­ject

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