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05-19-2010, 03:13 AM   #1
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Af's' & af'c'

I try to pre-focus with AF'S' and the AF keeps on focusing as I move the focus point. I don't understand.

What is the difference between the two? One focuses on more points?

Another thing that is confusing me, I have 'catch in focus' turned off but the shutter button is reluctant to let the camera shoot a picture in low light.


Last edited by fractal; 05-19-2010 at 03:18 AM.
05-19-2010, 04:18 AM   #2
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AFS = autofocus single.... once it has achieved lock it will not refocus, as long as you keep the button half pressed.

AFC= autofocus continous.... will not "lock" but will continue to search for focus.
05-19-2010, 06:14 AM   #3
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QuoteOriginally posted by pschlute Quote
AFS = autofocus single.... once it has achieved lock it will not refocus, as long as you keep the button half pressed.

AFC= autofocus continous.... will not "lock" but will continue to search for focus.
That's the problem I seem to be having and hence why I am posting. AFS will refocus when the button is half pressed. To put it more bluntly, it acts just like AFC.

Come to think of it, maybe my hand is just not steady enough.
05-19-2010, 08:58 AM   #4
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QuoteOriginally posted by fractal Quote
That's the problem I seem to be having and hence why I am posting. AFS will refocus when the button is half pressed. To put it more bluntly, it acts just like AFC.

Come to think of it, maybe my hand is just not steady enough.
If you have a camera model with the [AF] button, and your finger is too wobbly/touchy on the shutter release button, turn off [AF with half press] in the menus and use the [AF] button to focus. Your shutter button will then only enable shake reduction, Exposure and shutter release, and the camera does not care how hard you press the AF button.

05-19-2010, 08:59 AM   #5
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Hi Carl,

Another difference is that AF S is focus lock priority, it will only allow the shutter to fire once focus lock has been achieved. If you have a lens with focus clutch or Quick Shift focusing, you can readjust focus while holding focus lock.

AF C is shutter button priority. It allows the shutter to be fired even if focus lock has not been achieved.

Scott
05-19-2010, 09:04 AM   #6
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Use AF-C when shoot sporting or anything requiring movement and tracking, works very well I shot a soccer match in Egypt and it performed flawlessly with the SDM 50-135, I've tried it with the HSM Sigma 70-200 and it works very well to.
05-19-2010, 09:54 AM   #7
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and don't 4get in the Kx there is an AF-A mode which is AFS but will switch to AFC automagically when the camera senses that the subject is moving.
05-19-2010, 10:25 AM   #8
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Whether catch in focus is on or off, the camera won't fire if it hasn't achieved focus when your in AF-S mode. Also, you have to *hold* the shutter half-pressed to keep it from refocusing. It will keep trying to focus until focus has been achieved (you see the green hexagon light up and hear a beep if you've got that option enabled), but then won't change as long as you keep your finger on the shutter.

05-19-2010, 10:30 AM   #9
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Is it possible that you're not letting the focus get a lock before you move the focus point off where you had it? Alot of time it wil seem like the focus has locked, because it stopped moving, but it hasn't confirmed or actually locked yet, so when you move it, it will continue trying to focus on something.
05-19-2010, 05:27 PM   #10
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QuoteOriginally posted by fractal Quote
That's the problem I seem to be having and hence why I am posting. AFS will refocus when the button is half pressed. To put it more bluntly, it acts just like AFC.

Come to think of it, maybe my hand is just not steady enough.
Releasing the shutter button disengages focus. Half pressing engages it. So it does not matter if focus was locked before. If you release the shutter then half press, the whole focusing cycle restarts.

You may want to configure the camera to focus by using another button instead. On the DS it's the 'Ok'. I think it's the AE Lock on the K-x. Consult your camera manual.

Just remember that this prohibits focusing by half pressing the shutter. Many times i thought my camera was broken because it was not focusing
05-19-2010, 06:56 PM   #11
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QuoteOriginally posted by GrinMode Quote
Just remember that this prohibits focusing by half pressing the shutter. Many times i thought my camera was broken because it was not focusing
Hmm I imagine this could take some getting used to. But, if my shaky finger continues to be problem on AFS then I may look into this. Thanks all.
05-19-2010, 07:25 PM   #12
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Are you shooting in any particular scene mode?
From what I understand, depending on the mode, for example Fast Action mode, it will change to AF-C

Thanks,
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