VI­BRA­TION COM­PEN­SA­TION

The not-so-clear nomen­cla­ture that sur­rounds lens tech­nol­ogy leaves many feel­ing daunted, so here we break down one term: ‘ vi­bra­tion com­pen­sa­tion’, or VC for short

New Zealand D-Photo - - EXPLAINED -

Blurry im­ages are anath­ema to the pho­tog­ra­pher us­ing hand­held. The me­chan­i­cal work­ings of a cam­era might be first rate, but, in­tro­duce an im­per­fect world of trou­ble­some light, un­du­lat­ing sur­rounds, or tremor­ing limbs, and those pin-sharp pos­si­bil­i­ties go up in smoke. Luck­ily, man­u­fac­tur­ers have steadily been evolv­ing tech­no­log­i­cal so­lu­tions to th­ese shaky re­al­i­ties. The fix comes with many dif­fer­ent la­bels des­ig­nated by dif­fer­ent brands: vi­bra­tion com­pen­sa­tion, shake re­duc­tion, im­age sta­bi­liza­tion, vi­bra­tion re­duc­tion, shake cor­rec­tion. Each has its own pro­cesses and nifty acro­nym, but all work to­wards a uni­fied aim of elim­i­nat­ing un­wanted blur in­tro­duced through cam­era move­ment. This kind of blur (not to be con­fused with the mo­tion blur of a fast-mov­ing sub­ject, or the soft­ness of an out-of-fo­cus shot) is cre­ated by move­ment of the op­ti­cal path be­tween the lens and im­age sen­sor, ob­scur­ing the line of the light trav­el­ling within the cam­era. With­out the aid of sta­bi­liz­ing tech­nol­ogy, this is­sue is gen­er­ally com­pen­sated for by shoot­ing at shut­ter speeds fast enough that bod­ily twitches will not af­fect the re­sult­ing im­age. The rule of thumb for the slow­est us­able shut­ter speed when hand­hold­ing sug­gests tak­ing your fo­cal-length value and mak­ing it the de­nom­i­na­tor of your shut­ter speed. So, if you’re shoot­ing with a 50mm lens, you’ll want a shut­ter speed of 1/50s or faster. With a 300mm lens, don’t be slower than 1/300s. This is just a guide­line, and will de­pend on how surgeon-like an in­di­vid­ual pho­tog­ra­pher can hold the cam­era. With the in­tro­duc­tion of vi­bra­tion com­pen­sa­tion fea­tures, how­ever, those hand­held speeds can get a lot slower. The tech­nol­ogy, noted as “VC” in the lens’ long string of iden­ti­fiers, works by the lens of the cam­era unit de­tect­ing small move­ments in­tro­duced to a shot and mov­ing the lens el­e­ments or sen­sor to counter the shake. Dif­fer­ent man­u­fac­tur­ers have de­vel­oped slightly dif­fer­ent ways of achiev­ing this, with vary­ing de­grees of so­phis­ti­ca­tion and suc­cess, but all man­age to gift hand­held shoot­ers the op­por­tu­nity of shoot­ing at slower speeds, in tricky light, where pre­vi­ously there would be only dis­as­ter. So preva­lent and — with their many dif­fer­ent monikers — con­fus­ing have th­ese fea­tures be­come, that an in­de­pen­dent or­ga­ni­za­tion, the Cam­era and Imag­ing Prod­ucts As­so­ci­a­tion, has es­tab­lished a stan­dard to de­scribe, mea­sure, and com­pare the dif­fer­ent sta­bi­liz­ing tech­nolo­gies. The stan­dard quan­ti­fies per­for­mance in terms of ‘stops’, re­fer­ring to the jumps in shut­ter speed that can be achieved through the tech­nol­ogy. For ex­am­ple, where sta­bi­liz­ing can slow a min­i­mum hand­held shut­ter speed of 1/60s to 1/4s, that fea­ture is said to pro­vide four stops of sta­bi­liza­tion (i.e., the shut­ter speed is halved four times). Man­u­fac­tur­ers have ea­gerly em­braced this new stan­dard as a way of show­cas­ing the abil­i­ties of their in­di­vid­ual VC fea­tures. Tamron, for ex­am­ple, has just re­ported best-in-class re­sults un­der the sys­tem, with the new Tamron SP 24–70mm f/2.8 Di VC USD G2 clock­ing in an im­pres­sive five-stop re­sult. The new high-speed stan­dard zoom achieves this feat through Tamron’s ex­ist­ing Vi­bra­tion Com­pen­sa­tion tech­nol­ogy com­bined with a ded­i­cated mi­cro-processing unit (MPU) run­ning the num­bers. The VC sys­tem senses cam­era shake through three steel ball bear­ings con­nected to three driv­ing ca­bles, which elec­tro­mag­net­i­cally make ad­just­ments to the Com­pen­sa­tional Op­ti­cal Sys­tem within the lens’ VC unit. The in­clu­sion of a ded­i­cated MPU to the sys­tem al­lows the lens to use Tamron’s pow­er­ful new al­go­rithm to make ad­just­ments more quickly and ac­cu­rately than ever be­fore (the lens also uses a sec­ond MPU to drive its high-pre­ci­sion aut­o­fo­cus tech­nol­ogy, but that’s an­other ar­ti­cle). If that’s all a bit overly tech­ni­cal, just re­mem­ber; the more pow­er­ful an VC sys­tem is, the more stops it is rated. And (when paired for test­ing with a Canon 5D Mark III and Nikon D810) the VC fea­ture of the Tamron SP 24–70mm f/2.8 Di VC USD G2 is the cur­rent high-wa­ter mark for its class, at five stops. In prac­tice, this means you could get an im­age that would usu­ally re­quire a shut­ter speed of 1/60s when hand­held, down at 1/2s with­out hav­ing to worry about your shaky hands ru­in­ing the shot. Or, more sim­ply, shoot­ing by hand in low light is now no longer a prob­lem.

TAMRON SP 24–70MM F/2.8 DI VC USD G2 LENS Fo­cal length...................................................24–70mm Max aper­ture.......................................................... f/2.8 Min. aper­ture........................................................... f/22 Lens con­struc­tion.................. 17 el­e­ments in 12 groups Min. fo­cus dis­tance............................................ 0.38m Max mag­ni­fi­ca­tion ra­tio............................................ 1:5 Di­aphragm blades..................................Nine (cir­cu­lar) Vi­bra­tion com­pen­sa­tion................................ Five-stop Length ........................ 111mm Canon / 108.5mm Nikon Weight.............................. 905g Canon / 900g Nikon Mount type............................................................. EF, F

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.