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CAMERA SKILLS

When should I usedifferent focus modes?

Accurate focusing is critical forclose-up shooting. For total precision use a tripod,and adjust the focus manually, using Live View to magnify the key parts of the scene

My Canon D-SLRhas three different autofocusmodes, as we ll as manual options. So far, I'veon ly rea lly used AI Focus, and I'd like to know

if it's better to use other mo des fo r specific types ofshooting. What wou ld you recommend?Janet Banfield Gloucester

Peter says AI Focus is a decent starting po int,and it wo rk sokay for most shooting scenarios .

.._ Th e camera defau lts to One Shot (s ingle)autofocus mode, and locks onto the sub ject. However, ifthe sub ject starts moving, the camera automatica llysw itches to AI Se rvo (co ntinuous) au tofocus mode, andtracks its movement. Even so . f you know that whatyo u're shooting isgo ing to either remainstill. or bemoving, it's better to sw itch to One Shot or AI Servorespect ive ly. This avo ids any possible indec ision on thepart of the ea mera.One Shot mode wo rk s particularly well whenyou 'rese lec ting asingle autofocus po int, as yo u can choosethe AF po int closest to the most critical part of the scene.Alternat ively, rather than fiddling around se lecting

7/28/2019 Focus Modes

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STEP BY STEP Make the most of autofocus modes

One Shot11 This is great for everything from portraits tolandscapes, but the exposure is locked at thesame time as autofocus in Evaluative metering mode.If you're using a single AF point, and you autofocuson a particularly bright or dark object in a scene, theexposure is heav ily biased to that object.

AI FocusII5J For subjects that might move unexpectedly, like& small children, pets and other animals, AI Focusis a good choice. However, if you ach ieve autofocus andth en move the camera, fo r example when taking aportrait that 's off-centre in the frame , the cameragenerally won 't track any subsequent movement.

different AF points. many photographers use th etime- honoured tradition of sticking with the centralAFpoint. You can line th is up with a key feature. such as oneof the subJect 's eyes in a portra it shot, light ly press andmaintain pressure on the shutter button to achieve andlock autofocus, then swivel the came ra to recomposeth e shot before fu lly pressing t he button.

The only problem with this met hod is that, inEva luative metering mode, the exposure setting islocked at the same moment that autofocus is atta ined.If the overall scene is rather lighter or darker afteryou've swivelled the camera after ach ievi ng One Shotautofocus, the res ul t ing image is likely to be overexposed or underexposed. A neat trick is to use theCentre-weighted metering mode instead.ln th is case,meter ing and exposure settings wi ll be conti nuouslyupdated in real time as you swivel t he camera.

For moving targets, AI Servo is usua lly the bestchoice. The autofocus system t racks the su bject

AI Servom Id ea l for tracking moving objects, AI Servo works.. ontinuously while the shutter button is lightlypressed. lt can struggle to track objects moving quicklytowards or away from the camera, but is usually fine fo rpanning. Lenses with fast, ring-type USM autofocus aregenerally more able to track faster-moving objects.

Focus pointsl ln For front-to-back sharpness in landscape images,- autofocus on a point about a third of the way intoth e scene, and use a narrow aperture of around f/11 tof/ 16 . Und er g loomy lighting, increase your ISO sett ingto enable a faster shutter speed; this wi ll avoid motionblur. as we ll as camera-shake in handheld shots.

automatically as it moves nearer or furt her away, andit works particularly we ll with a multi-point AFsetting.The camera uses th e centralAF point initially, so makesure you line this up with the ma in ta rget. However, if thetarget is moving erratica lly, and strays from the centralarea of the frame, the camera switches to other AFpoints to track it The only real pitfal l of AI Servo is whentargets are moving ve ry quick ly, as the autofocus systemmay not be able to keep up with them. If you know thepoint at which you wa nt to shoot your subject- a bendon a motor racing circuit for example- it's better to useOne Shot autofocus mode, and pre-focus on that spot

For close-up and macro shots, focusing is especiallycritica l. You need to avoid swive ll ing the camera, ormoving it in any way, after focusing. it's therefore betterto use a tripod, and switch to Manual foc using mode sothat you can lock the focus on the exact spot you wantBetter st ill, switch to Live View, and use a magnified viewon the camera's LCD for precise focusing .,..