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12-04-2013, 03:29 AM   #1
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K-3's AF.C with Focus priority.

I received K-3 yesterday. I began testing its AF.C speed with my Tamron 17-50/2.8. In order my test to be not as subjective, I decided to press the shutter button all the way down and point the camera at different objects. My AF mode was AF.C + Focus priority. As far as I understood, the shutter wouldn't release until the lens is fully focused.
However it turned out that I got shutter releases even before the camera fully focused as though it was not in Focus priority but in Release priority. I even pointed my camera at objects that were closer than minimum focusing distance of my lens. There shouldn't be any shots at all but there were. I had the same experience when I had K-5 IIs. Why is that? Does the Focus priority work or maybe I'm doing something wrong?


Last edited by skyer; 05-06-2014 at 09:21 PM.
12-04-2013, 03:36 AM   #2
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Are you using the AF button for focusing?

EDIT: I thought button customisation made a difference, but apparently the only real influence is AF.S vs AF.C.

Last edited by Class A; 12-05-2013 at 01:51 AM.
12-04-2013, 03:41 AM   #3
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Yes, Class A, I switched AF to the AF button. I also remeber that issue with K-5 IIs. I hoped it is all worked out now with K-3. After noticing that it was not, I switched back to AF+shutter release button but it didn't work either!
12-04-2013, 04:58 AM   #4
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Oh, thank you for the good thought to configure AF button to Cancel AF.
There are 3 options for the AF button in K-3:
1. Enable AF1 (AF is performed when AF buton is pressed);
2. Enable AF2 (AF is performed when AF button is pressed and not when the shutter release button is pressed halfway);
3. Cancel AF (while AF button is pressed, AF is not performed even when the shutter release button is pressed halfway).

"Enable AF1" is a default mode. I tried "Enable AF1" and "Enable AF2". Now I should try "Cancel AF". If it works, I will assign the setting to one of the user modes.
However, I totally agree with you that such behaviour is really weired.

12-04-2013, 01:42 PM   #5
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It looks like "Cancel AF" doesn't work either (in terms of Focus priority).
Could anyone with a K3 check this feature on your camera?

Last edited by skyer; 12-04-2013 at 01:58 PM.
12-04-2013, 03:08 PM   #6
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QuoteOriginally posted by skyer Quote
It looks like "Cancel AF" doesn't work either (in terms of Focus priority).
Could anyone with a K3 check this feature on your camera?
you're right. the af.c shoots all the time .. no matter the combination . in the manual ( page 45 ) says at af.c- "the shutter can be released even if the subject is not in focus".
i have tried also with continuous shooting . the same.
also tried multiple af points/spot.. nothing.
only the af.s works
12-04-2013, 03:22 PM   #7
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Priority doesn't mean something MUST happen, it is a preference to an alternative if something is possible/desirable. A get-out clause in fact. There should be 3 AF-C options, the extra one being a MUST be in focus option.
12-04-2013, 03:30 PM   #8
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QuoteOriginally posted by SteveB Quote
Priority doesn't mean something MUST happen, it is a preference to an alternative if something is possible/desirable. A get-out clause in fact. There should be 3 AF-C options, the extra one being a MUST be in focus option.

lol....that sounds like the answer a Pentax lawyer would provide. But unfortunately its probably the truth. I had been mulling this over since the OP posted and realized none of my Pentax bodies actually force focus before shooting. Now I will have to try and do some definitive testing of k-5, k5iis and k-3 as this is now a bug up my butt (no macro shots allowed).


Give me a couple days and I will post something for argument.

12-04-2013, 09:29 PM   #9
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It's a pity that Pentax hasn't implemented the Focus Priority feuture in AF.C mode. I think that continious shooting with focus priority would have made a "in focucus shots/all shots" ratio much better. Usually one doesn't need a whole bunch of images that a out of focus. It's better to have few but all tack sharp.
12-04-2013, 10:15 PM   #10
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QuoteOriginally posted by skyer Quote
It looks like "Cancel AF" doesn't work either (in terms of Focus priority).
I've just checked this with my K-5 II and focus priority only works in AF.S as you would expect it.

In AF.C, even out of focus shots are taken, no matter the button customisation.

Probably SteveB is right and "focus priority" in AF.C just means that the camera will make an effort to achieve focus before it fires a shot, but if focus cannot be obtained then it will take a shot nevertheless (after a certain tolerance period).

The alternative, a bug, seems too unlikely.

Last edited by Class A; 12-05-2013 at 01:51 AM.
12-04-2013, 10:40 PM   #11
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If it's not a bug then what about the C3 16 in K-3 menu?
K-3 got a new menu item - "1st Frame Action in AF.C" with such options:
1. Release Priority (default setting);
2. Auto;
3. Focus Priority.

Here I walso selected "Focus Priority". Presumably, it means that an AF.C series won't start until focus is obtained and at least the first frame in every AF.C series should be in focus. Nevertheless it doesn't help either. There still come shutter releases when a camera can't find focus at all.
12-05-2013, 12:38 AM   #12
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QuoteOriginally posted by skyer Quote
If it's not a bug then what about the C3 16 in K-3 menu?
K-3 got a new menu item - "1st Frame Action in AF.C" with such options:
1. Release Priority (default setting);
2. Auto;
3. Focus Priority.

Here I walso selected "Focus Priority". Presumably, it means that an AF.C series won't start until focus is obtained and at least the first frame in every AF.C series should be in focus. Nevertheless it doesn't help either. There still come shutter releases when a camera can't find focus at all.
well ... that's the problem. also i find the the catch in focus doesen"t work on MF .. could this be a software problem?
12-05-2013, 01:50 AM   #13
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QuoteOriginally posted by burb Quote
well ... that's the problem. also i find the the catch in focus doesen"t work on MF .. could this be a software problem?
Catch-in-Focus is only meant to work in AF.S mode.

You need an MF lens or a lens that allows setting it to MF. The camera needs to be set to AF.S.
12-05-2013, 05:02 AM   #14
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The focus priority does indeed work but perhaps a bit differently from what one would expect. It does not prevent the shutter from releasing indefinitely, it simply gives a bit more time to focus.If you set continuous high you will notice the big difference between focus and release priority. In releas priority you get the full 8 frames a second regardless of focus whereas with focus priority you still get the 8FPS if pointed at something still whereas if you move the camera around randomly while shooting the FPS will slow down a lot, to about 2FPS or less.

In other words although it is focus priortiy it actualy imposes a sort of deadline, which seems to be about a half or third of a second, after which it will fire anyway, focus or not.


I think there is a good reason behind this and wouldn't want it to be different. Sometimes you don't want to miss a shot, even if it isn't perfectly in focus and the most frustrating thing that can happen is to have the camera refusing to release the shutter no matter how hard you press it making you lose that once in a lifetime shot. The way they implemented seesm to me a good compromise between the two extremes.

Now that's an idea, maybe they should make a three stage shutter button where the last stage, which you would need to press very hard, would override any of the other priorities and fire no matter what. Perhaps I shouldn't have mentioned it here and applied for a patent instead,
12-05-2013, 11:28 PM   #15
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If it is so then it would be a better idea to add another item to the C3 17 "Action in AF.C continious" menu:
1. Focus Priority;
2. Auto;
3. FPS Priority:
4. FOCUS PRIORITY LITERALLY.


However, I still don't think that K-3's Focus Priority is not a shutter release priority with some emphasizing on AF. It could be so but then what's the point of including C3 16 "1st Frame Action in AF.C" menu?
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