Back-button focusing
24 DigitalSLR PhotographyJuly 2019
1
STRAIGHTOUTOFTHEBOXUsingdefaultsettings,yourcamerawill
autofocuswhenyouhalf-depresstheshutterbuttonand,depending
onwhichfocusmodeyouhaveit in,willbehavein differentways.In
allfocusmodes,however,half-pressingtheshutterbuttonactivates
autofocus,beit single-shotorcontinuous/AI-Servo.Fullypressing
theshuttertakesa photoanddeactivatesautofocus,andreleasingthe
shutteralsodeactivatesautofocus.In single-shotmode,yourcamera
won’tcapturetheimageunlessfocusis confirmed,whereas
in continuous/AI-Servomode,it capturesregardlessof focus.4
PUTITINTOPRACTICEBack-buttonfocusingwilltakea littlewhileto
adjustto,butit is moreeffectivewhenshootingfast-pacedaction.
Pressingandreleasingtheshutterbuttonnolongertellsyourcamera
tostopautofocusing,meaningthatyou’rereadytotakethenextframe
straightaway.You’realsonolongerdelicatelyholdingtheshutter
buttonwaitingfortherightmoment,whichhelpsthebalanceof the
camerain yourhandwhentrackinga movingsubject.Stickwithit –
back-buttonfocusinggivesyoumorecontrolandwill speed up your
shooting technique and accuracy in the long run.3
USINGBACK-BUTTONFOCUSOncedone,remembertochangeyour
camera’sAFmodetoContinuous(Nikon)orAI-Servo(Canon).
Now,whenyourpressandholdthebackbuttonwithyourthumb
thecamerawillfocuscontinually.If youwanttofocusonceandthen
recompose,simplywaituntilfocusis achievedandthenreleasethe
backbuttonandrecompose.If youwanttotrackfocusona moving
subjectthensimplyfollowthemwiththefocuspointandkeepyour
thumbpresseddown,andif youwanttomanually focus simply don’t
press the back button and turn the focus ring.W
HENYOUFIRST unpacka newcamerafromitsbox,it takesa
fewpersonaltweakstogetit setupthewaythatyou’dlike.
You’veusuallygottoremembertosetthefilequalitytoRaw
ratherthanJPEG,aswellaschangeit fromselectingAutoISO,andset
thedateandtime.Oftentherewillbeoneortwocustomfunction
changes,whichcanbemappedtoanynumberofcontrolsor
shortcuts,makingusingthecameramoreintuitiveandslicker.But
onecustomisablecontrolthatmostbeginnerstendtoleavealoneis
howtoactivateautofocus,andit mightsurpriseyoutohearthatthe
wayyourcamerais setuptodothis,andthewayyou’remostlikely
usedto,oftenisn’tactuallythebestwaytogoaboutit.
Bydefault,yourcamera’sshutterbuttonbothactivatesautofocus
(half-depress)andcapturesanimage(full-depress).We’resousedto
theactionsofautofocusingandtakingthephotobeingonthesame
buttonthatweoftendon’trealisehowclumsythiscanbe.Well,
there’sananswer– youcanactuallyseparatetheautofocuscontrol
fromtheshutterrelease,andit’sa trickthatmanysportsandaction
professionalsswearby– it’scalledback-buttonfocusing.
Youmightwonderwhyyou’dwanttoaddanextrabuttonor
controltotheprocess,butbyswitchingtoback-buttonfocusing,
you’reactuallyremovinga stepin thelongrunasyounolongerhave
toeverswitchbetweensingle-shotandcontinuous/AI-ServoAF
again.Usingback-buttonfocusing,youcangofromshootingstatic
subjectstomovingones,focusingandrecomposing,andevenfocus
manually,withoutchangingthefocus mode once, and therefore risk
forgettingtochangeit back.2
CUSTOMSETTINGSBack-
buttonfocusingis so
calledbecauseyoumove
theautofocusactivation
totheAF-ON,AE-Lockor
asteriskbuttonontheback
of thecamera,andaway
fromtheshutterbutton.
Onceactivated,yourthumb
controlsautofocusandyour
indexfingercapturesthe
image– it soundscomplex,
butyou’llgetusedtoit very
quickly.Exactstepsvaryfrom
modeltomodel,soconsult
yourmanual,buthere’show
toactivateit onmostCanon
and Nikon models...CANON:Formodelswitha rearAF-ONbutton,headintotheCustom
Controlsmenu,andchangetheshutterbuttonhalf-presstoMetering
only.Formodelswithouta rearAF-ONbutton,in the Custom Functions
menu, you want to set it to 3: AE/AF, no AE lock.NIKON:If yourcamerahasa rearAF-ONbutton,gototheCustom
Settingsmenu,thenselectAutofocusandsetAFactivationtoAF-ON
only.FormodelswithoutanAF-ONbuttonontherearofthecamera, in
the Controls section go to Assign AE-L/AF-L and set it to AF-ON.