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06-24-2010, 09:23 PM   #1
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K7 question: AF button does not lock AE when configured to do so

Hi,

On my K7 in P mode when I configure the AF button to lock AE (C2.13 set to Cancel AF) with AF button lock enabled (C1.5 ON) it will not lock AE in AF-C (AF is locked with the AF button pressed but not exposure). However the AF button will lock AE in AF-S.

When I switch to Av, Tv or TAv mode with the AF button pressed, AE won't lock in either AF-S or C.

I've tried all the above with and without setting AE to link to AF point in multipattern (and meter lever is set to multipattern).

I was hoping I could leave camera set to AF-C full-time and press the AF button to lock everything (AE & AF), simulating behavior of AF-S & half-press.

What am I overlooking?

thanks,
Fred

06-24-2010, 10:47 PM   #2
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I'm a bit confused with your description of the problem.

If you set C2.13 to Cancel AF, that setting is meant as a quick 1-button temporary override to switch to Manual Focus.

Some people find this function useful, but it won't give you AF-C even if you set AF-C on the focus mode lever.

If you want to disable Half-press shutter button focus, you should set that on C2.14 to No, keep C2.13 on Enable AF, so that you now solely focus with the AF button.
You need to continuously press the AF button to lock AF, which I find a bit awkward.
06-24-2010, 11:17 PM - 1 Like   #3
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As I said to your other thread (on the other forum):

I've done the same settings on occasion (cancel AF with AF-C).

My conclusion (and with hindsight, it's pretty obvious) is that this method cannot lock AE.

Obvious, because AF-C doesn't lock AE, and AF button only cancels AF (and does not really turn AF-C into AF-S).

So, I'd say that in this case, you'll have to first press AE-L, then AF to cancel AF-C...

Quite a lot of button pressing to mimic AF-S, no?

An interesting feature I stumbled upon while testing all this is that in AF-S with AF button set to "Cancel AF", a press/release on the AF button triggers a new autofocus cycle.

This means that you can wait half-pressed for the crucial moment (so SR is always active and ready), with periodical AF adjusts to follow your subject.

Last edited by dlacouture; 06-25-2010 at 12:04 AM.
06-24-2010, 11:35 PM   #4
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QuoteOriginally posted by dlacouture Quote
This means that you can wait half-pressed for the crucial moment (so SR is always active and ready), with periodical AF adjusts to follow your subject.
*runs to his camera to try this*

Well, I'll be! I just learned something. That just changed my default usage from Enable AF to Cancel AF.

Thanks!

06-24-2010, 11:38 PM   #5
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QuoteOriginally posted by dlacouture Quote
An interesting feature I stumbled upoin while testing all this is that in AF-S with AF button set to "Cancel AF", a press/release on the AF button triggers a new autofocus cycle.

This means that you can wait half-pressed for the crucial moment (so SR is always active and ready), with periodical AF adjusts to follow your subject.
You can do it just by moving AF function from release button to AF button.
If I need to re-AF - I use separate button, not release one.
06-25-2010, 12:03 AM   #6
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QuoteOriginally posted by Zebooka Quote
You can do it just by moving AF function from release button to AF button.
If I need to re-AF - I use separate button, not release one.
Yeah, I know, but this complicates things when I give the camera to my wife...
And given my ratio of use (maybe 5% of my shots use this method), I find it easier this way...
06-25-2010, 02:25 AM   #7
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QuoteOriginally posted by Zebooka Quote
You can do it just by moving AF function from release button to AF button.
If I need to re-AF - I use separate button, not release one.
Very true, but as Kitty said above, I can also see how that could get awkward over time.
06-25-2010, 02:56 AM   #8
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The original problem arises because in Pentax AE-lock doesn't mean AE-lock. It locks it just for some seconds, or until you adjust something else like the focus point or the flash output.
The easiest workaround is to use M + Green button to adjust for exposure, possibly also setting the Green button function in M (C4.28) to some special setting you like. Then you get consistent lighting and BTW if you set your flashgun to HS it will work as fill-flash, not influencing the ambient light reading.

06-28-2010, 01:51 PM   #9
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Original Poster
Thanks much for your replies! My K7 is my first digital SLR after upgrading from a Nikon FA. With so much user control there seem to be at least a couple different ways to do any one thing and some things don't seem to work as I think they should at first read.... all your experience & insights are greatly appreciated.

A follow-on question: in what situations is the function of locking AE with an AF button press useful?
07-02-2010, 01:25 PM   #10
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QuoteOriginally posted by fporter Quote
Thanks much for your replies! My K7 is my first digital SLR after upgrading from a Nikon FA. With so much user control there seem to be at least a couple different ways to do any one thing and some things don't seem to work as I think they should at first read.... all your experience & insights are greatly appreciated.

A follow-on question: in what situations is the function of locking AE with an AF button press useful?
I find this useful sometimes when I'm not shooting on M. It is particularly helpful for strongly back lit subjects, i.e. stood in front of the window. With spot metering on, and centre focus point selected focusing on the subjects face will ensure that the person is properly exposed and also in focus.
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