AF-ON how many use it and what are it's merits

Started Mar 12, 2007 | Discussions
JasonOdell Senior Member • Posts: 2,282
Re: AF-ON how many use it and what are it's merits

It's my primary mode of focusing.
More on my rationale for using it here:

http://www.luminescentphoto.com/articles/CAM2000/cam2000.html

-Jason

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Author, 'The Photographer's Guide to Capture NX'
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Builder Contributing Member • Posts: 921
Re: what john said

I'm struggling to wrap my head around this too, but if it works they way you describe, that would be awesome!

Tom Christiansen Senior Member • Posts: 2,239
Re: You be in control..not the camera

fudgebrown wrote:

John, forgive me for not simply reading my own D200 manual but i
have a question -

does that mean the AF-ON button while held down is essentially
AF-C, and as soon as you let go it locks focus - then you can take
your shot?

Not quite. The AF-ON button has no effect on AF-Lock. That's a
separate but close-by button. If you have the camera set to
Focus Prioirty, you'll have to learn the thumb roll-off from AF-ON to
AF-Lock. I usually keep the camera in AF-C and Release Priority
myself, using AF-ON for continuous autofocus. When chasing
birds in flight, I keep my thumb down on the AF-ON in Group Dynamic
Area AF, which sometimes gets a little tedious, since I need to
keep the shutter half-engaged to preserve VR anyway.

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tom

vbd70
vbd70 Veteran Member • Posts: 6,378
gotta love those canon fanboys...

Good job Jeff - someone might have believed him...

Best regards,

Vieri

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Builder Contributing Member • Posts: 921
Re: AF-ON how many use it and what are it's merits

Ok, I've just had a play with this... It looks like you have to do the following:

1. Change a2 AF-S mode priority to release
2. Change a6 AF Activation to Off

John mentioned both of these, but I didn't quite understand what he meant until I looked at the menu options.

If you don't change a6, when you press the shutter half way in, it will refocus. If you don't change a2, the shutter won't fire if you've moved the active AF sensor off of the target of your photo.

I'm still debating whether I want a2 AF-C mode priority to FPS rate or leave it on focus. Opinions on this would be appreciated

Tom Christiansen Senior Member • Posts: 2,239
Re: AF-ON how many use it and what are it's merits

Builder wrote:

If you don't change a6, when you press the shutter half way in, it
will refocus. If you don't change a2, the shutter won't fire if
you've moved the active AF sensor off of the target of your photo.

Unless you've first depressed the AF-Lock button (AE-L/AF-L).
You can have AF-C and Focus Priority and AF-ON focussing only,
but you need to then use the AF-Lock button. I didn't understand
this myself at first.

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tom

Kabe Luna
Kabe Luna Veteran Member • Posts: 9,496
Reading comprehension isn't one of your strengths, I see.

Canon started it with a custom function allowing you to move AF from the shutter button to the AE lock button on the top right corner of its EOS film cameras, beginning with the EOS-1 in 1989. Moreover, I gave Nikon and Pentax their due credit for going one better and dedicating a button for this rather than forcing one to sacrifice some other function to gain it:

"–in fact going one better with a dedicated control for it."

As for Contax, though they exhibited the first working prototype of a 35mm AF SLR in 1982, they didn't even have a production AF 35mm SLR until the AX of 1997–eight years after Canon debuted this feature on the original EOS-1 in 1989–so I have to laugh at your suggestion that they originated the idea. Perhaps you know of a magical pre-1989 manual focus Contax with a dedicated AF-on button the rest of the world doesn't?

jeff-c wrote:
Since when Canon has a dedicate AF-ON button?

In fact they just add this button first time to their newly
released EOS-1D Mark III due to popular demand.

Contax has been using this for long time.

Kabe Luna wrote:

This is an idea I'm glad Nikon and others have taken from Canon–in
fact going one better with a dedicated control for it. I detest
cameras with AF coupled with the shutter release, and in fact this
is the one thing that drove me to Canon so many years ago.

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Kabe Luna
Kabe Luna Veteran Member • Posts: 9,496
Yes, cracking good job.

vbd70 wrote:

Good job Jeff - someone might have believed him...

Best regards,

Vieri

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Joseph S Wisniewski Forum Pro • Posts: 34,165
Constantly, for focus accuracy...

michael wrote:

I would be interested on how many of you use this button and why ?

I've been using it since film days (F100 can work the same way).

You control when focus starts, you'll be able to see that it's converged before the shutter fires. And, if shooting something like gymnastics, you can use it to pre-focus on a point where you know something will be happen, then shoot when that something does happen.

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Ciao! Joe

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C_4 Contributing Member • Posts: 545
Re: AF-ON how many use it and what are it's merits

I don't use AF-On as much as I should, but it's mainly an ergonomics issue for me.. On the D2 series pro-bodies, the button is simply too far over for my thumb to reach easily.. By comparison, I used to use it quite a bit on the D1, where the button was positioned just a bit further over to the right, where I could reach it easily.. Even with the vertical grip, I don't use it much because although the D2-series replaced the tiny rubber button of the D1 with a hard chiclet key, it's a bit recessed into the body and requires that you bend your thumb and use the tip to press; using the pad of your thumb seems to require a lot of pressure, probably because of the recessed design and the relative size of your thumb..

Because of these issues, I've pretty much given up on AF-ON and use the shutter half-press to lock focus..

I do use the AE-Lock button though, but I've got mine set to an push on/push off toggle operation vs. the default hold-on, release-off.. In this way, I can push the button and let go and not worry about keeping my thumb stretched over and holding the button..

Randy Z Senior Member • Posts: 2,560
Biggest advantage for me

I can focus/recompose only once for a series, and don't have to keep the shutter button half-pressed.

Disadvantage: You can't hand the camera to a friend to take a shot without re-enabling the shutter button focus.

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Z-Man

vbd70
vbd70 Veteran Member • Posts: 6,378
Reading vs writing...

Kabe Luna wrote:

This is an idea I'm glad Nikon and others have taken from Canon...

Kabe, the OP talked about AF-ON button, you answered "this is an idea..." - my reading comprehension is pretty good, and I got your "this" meaning the "AF-ON" button mentioned in the OP's post. As did Jeff. So maybe can it be the writing in your first that had some problem with not being complete and, at best, cryptic instead?

I detest cameras
with AF coupled with the shutter release, and in fact this is the one
thing that drove me to Canon so many years ago.

Again "this" answering a post about the "AF-ON" button - see above for comprehending what you really mean.

Canon started it with a custom function allowing you to move AF
from the shutter button to the AE lock button on the top right
corner of its EOS film cameras, beginning with the EOS-1 in 1989.
Moreover, I gave Nikon and Pentax their due credit for going one
better and dedicating a button for this rather than forcing one to
sacrifice some other function to gain it:

Cool. Now you explain it, and now reading it one can understand your point. In your first reply, only a mind-reader would have be able to understand what you really meant. I do agree with you on this and especially on the better implementation of Nikon's AF-ON - finally Canon pick up to it, I am glad for all Canon users, and this might be something that would make a move towards Canon easier for me if needed (which IMHO is a major reason for Canon to add this feature...). I am so used to AF-ON I couldn't imagine going back to half-pressing the shutter.

Best regards,

Vieri

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jaba Contributing Member • Posts: 861
Re: AF-ON how many use it and what are it's merits

kevm14 wrote:

But doesn't VR need a moment to stabilize itself? Like, about the
time it takes to auto focus? I agree on the battery thing though...

Yes, but at time you are just looking thru the viewfinder to catch the moment and by using only AF-On you can have the AF on demand and only get the VR to work when you are taking the exposure. Anyway, the time the VR needs to work is more or less the time I need to think and shoot... It is pretty fast... or I am pretty slow.

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Julia Borg Veteran Member • Posts: 7,280
Re: Reading vs writing...

In your first reply, only a mind-reader would have be
able to understand what you really meant.

any Canon shooter can understand meanings here, and in fact even a non-Canon shooter non-mind-reader can understand best intentions

still, there was no AF-ON button

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Julia

OP michael Regular Member • Posts: 273
Re: You be in control..not the camera

John Cote wrote:

michael wrote:

I would be interested on how many of you use this button and why ?
--
Michael
http://www.pbase.com/yube
http://www.shuttercity.com/ShowGallery.cfm?AcctID=1854

Michael,

If you use the shutter button, you need to press an AF lock button
or the camera will refocus when you take a photo. I want the camera
to be focused on what I focus it on. Not some high contrast area it
likes near what I want of a fence behind the subject.

Switching focus to the AF-ON button and off of the shutter button
means that after I take my finger off the AF-ON button, focus is
locked. When I take the picture the camera can not re-focus.

To me, focusing and taking are two different functions. I do not
want the to happen together with the press of a single button.

Thanks John for your thorough reply, just so as to get my head round it a little more .... You press AF-ON Button and release it .. this locks the focus.. re-compose and take the shot ... Do you then need to re-press the AF-ON button to release the previous focus or does it automaticaly release after the shot is taken.

Michael
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Tom Christiansen Senior Member • Posts: 2,239
Re: You be in control..not the camera

michael wrote:

Thanks John for your thorough reply, just so as to get my head
round it a little more .... You press AF-ON Button and release it
.. this locks the focus..

FALSE

It merely discontinues focusing. There is no lock, unless you were
in AF-S mode to begin with.

re-compose and take the shot ... Do you
then need to re-press the AF-ON button to release the previous
focus or does it automaticaly release after the shot is taken.

And see where this confusion leads?

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tom

vbd70
vbd70 Veteran Member • Posts: 6,378
which

is exactly what I meant. No AF-ON button.

Best,

Vieri

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devenh Contributing Member • Posts: 895
Re: what john said

Does it go something like this? Say I'm shooting kid soccer with
AF-C, AF-ON and using the center sensor. Press and hold the AF-ON
button. Since I'm using AF-C, then the AF is continuously
working/focusing. At the moment of peak action, say a header, then
release AF-ON and press the shutter?

No, you do not have to release the AF-ON button before taking the shot. In fact, if you are taking a series of photos then you may very well be pressing both buttons simultaneously.

Another useful aspect of the AF-ON button is that if you find that the AF has locked on to something in the background, then you can quickly "reset" the focus by "pumping" the AF-ON button (releasing and re-engaging the button, sometimes more than once).

Definitely much harder to describe than actually do. It does take a while to get used to it, but as others have commented, once you learn how you rarely go back to using the shutter release button to engage the AF.

Deven

winnie Veteran Member • Posts: 4,224
Thomas

I just tried this out and I am not sure I get this at all.

I set the AF-ON to be the only focus mechanism in the menu and sure enough that is all I could use to focus, fine up to this point. If I then release the button and move away from the focused area I couldn't take the image. Although if I moved back to the focused area and pressed the shutter release it would beep and let me fire? Is that right?

Very confusing but as I have only had it a couple of days I am sure I will get it eventually.

Cheers

Alex
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http://www.alexwinserphotography.co.uk

Thomas Comerford Veteran Member • Posts: 9,745
Re: Thomas

That's because you're using AF-S, and by default AF-S is configured to be focus-priority. You could reconfigure AF-S to be release priority, but a better option is to just switch to AF-C instead.

winnie wrote:

I just tried this out and I am not sure I get this at all.

I set the AF-ON to be the only focus mechanism in the menu and sure
enough that is all I could use to focus, fine up to this point. If
I then release the button and move away from the focused area I
couldn't take the image. Although if I moved back to the focused
area and pressed the shutter release it would beep and let me fire?
Is that right?

Very confusing but as I have only had it a couple of days I am sure
I will get it eventually.

Cheers

Alex
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http://www.alexwinserphotography.co.uk
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