Confused about AFS & AFC

ajamils

ajamils

Well-known member
From the manual AFC (Auto Focus Continuous) is defined as

"This mode allows you to compose a picture more easily by continuously focusing on the movement of the subject while the shutter button is pressed halfway."

So does that mean when I'm making a video I have to keep the shutter half pressed all the time ?? My understanding was that if set it to AFC, it will function like camcorder and automatically focus on things as I move the cam around. Am I understanding it wrong ?

Also, is AFC only used for video or can it be used for stills as well ?
 
For video there are only two modes for focus (as set by the knob), manual and continuous. You don't have to press the shutter button unless you think it's not correctly focussing, when a half press will cause it to rethink (but you'll see it do it in the footage).

There's a menu setting for having focus for photos constantly updated without pressing the shutter halfway, but in that mode it runs the battery down faster.
 
AFC = "continuous"; AFS = "single shot" -- i.e., you have to hold the button down halfway to get autofocus to happen, whereas with AFC it's always autofocusing.
 
Battery life.

I personally use AFS if I'm taking photos because I am used to it coming from Point and Shoots and other SLRs....

Although I almost always use manual and manual lenses...I am not a big proponent of auto focus (though i understand the purpose...but if you spend a lot of time getting good at manual focusing it's totally worth it...but again autofocus does have it's purposes.)
 
I think we're adding to the confusion here!

For stills -

AFS - does a single focus operation when you half press the shutter. Let go of shutter, focus stays fixed. Continue to hold shutter half pressed, focus stays fixed too.

AFC - does a continuous focus operation while you half press the shutter (and will refocus as required while you continue to half press the shutter). This is useful if something is moving towards you or away and you want the focus to stay correct until you fully press the shutter. Also handy if the subject is static and close but you are rocking back and forward! Let go of shutter and it stays fixed at last position. It does not continue to focus.

See page 52 of the manual for those options, and note that in some light conditions, AFC will not work, and you'll see the AFS indicator come up in the viewfinder to warn you.

Now if you want focus to be on constantly for stills regardless of whether you half press the shutter, (with consequent reduction of battery life), you must turn on "Pre-AF" in the Custom menu. And just to complicate matters there are two flavours of Pre-AF. I can't do better than the explanation on page 127 of the manual of these options. Well, OK, one option focusses when you hold the camera still (which indicates you're about to take a photo), and the other focusses regardless.
 
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