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09-02-2014, 04:08 PM   #1
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The K-3 and Back Button Focusing

So I have my K-3 set to AF-C with SEL 2 and the focusing to AF2, i.e only focus when pushing the AF-button.

When using this way of focusing I find that the focus is not dead on when shooting an object that is not moving, for instance a landscape.

If I set it to AF-S/SPOT/AF2 I get a good lock on the focus but when trying to get the same result with the AF-C/SEL2/AF2-combo I am out of luck most of the times.

So; How are your experiences with the K-3 and Back Button Focusing? If you get it right; What am I doing wrong?

Been testing it for quite some time now...

09-02-2014, 04:47 PM   #2
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Well, someone in this Forum - sorry I cannot remember whom to credit - had these suggestions for the following settings in the Custom Settings menu:

C.16 (First Frame Action in AF.C) = 3 (Focus Priority)
C.17 Action in AF.C Continuous Shooting = 1 (Focus Priority)
C.18 Hold AF Status = 3 (Medium)

I have adopted those, and whether I shoot Single Frame or Continous, this has worked fine for me since. However, I do change the focus point setting from situation to situation. According to the manual SEL 2-4 are intended for moving objects / objects that might move away from the focus point, but that shouldn't really matter?
09-03-2014, 04:14 AM   #3
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QuoteOriginally posted by Stone G. Quote
Well, someone in this Forum - sorry I cannot remember whom to credit - had these suggestions for the following settings in the Custom Settings menu:

C.16 (First Frame Action in AF.C) = 3 (Focus Priority)
C.17 Action in AF.C Continuous Shooting = 1 (Focus Priority)
C.18 Hold AF Status = 3 (Medium)

I have adopted those, and whether I shoot Single Frame or Continous, this has worked fine for me since. However, I do change the focus point setting from situation to situation. According to the manual SEL 2-4 are intended for moving objects / objects that might move away from the focus point, but that shouldn't really matter?
C.16 and 17 is the same for me but C.18 is put to OFF.

I will try the Hold AF but that will counteract the speed of the AF when following moving targets...
09-03-2014, 07:16 AM   #4
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Does it find focus then adjust away from it? It may be lens dependent. I have two DA300's (long story) one focuses reliably, the other one does what I describe. Both with the 1.4TC. My 35mm macro did the same until I did the lens af adjustment.

09-03-2014, 09:11 AM   #5
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QuoteOriginally posted by derekkite Quote
Does it find focus then adjust away from it? It may be lens dependent. I have two DA300's (long story) one focuses reliably, the other one does what I describe. Both with the 1.4TC. My 35mm macro did the same until I did the lens af adjustment.
The thing is if I use AF-S it will lock on and stay there and focus is sharp where I intended. With the AF-C it locks on but it is like if I have a little bit of front or back focus. I let go of the AF-button as soon as the camera beeps for AF-lock. I do not think it is moving away like you describe but I will have to test again.

Does you lens/lenses move away, as you describe it, when in AF-S?

My eyesight is not as good as it used to be so I depend on the AF when things are moving.

Would love for this to work as intended so that I no more need to change the AF-modes all the time.
09-03-2014, 09:22 AM   #6
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QuoteOriginally posted by Tjompen1968 Quote
The thing is if I use AF-S it will lock on and stay there and focus is sharp where I intended. With the AF-C it locks on but it is like if I have a little bit of front or back focus. I let go of the AF-button as soon as the camera beeps for AF-lock. I do not think it is moving away like you describe but I will have to test again.

Does you lens/lenses move away, as you describe it, when in AF-S?

My eyesight is not as good as it used to be so I depend on the AF when things are moving.

Would love for this to work as intended so that I no more need to change the AF-modes all the time.
When you let go of the AF on button do you move the camera? Even slightly? This can simulate the back focus.

I use AF.C with the AFON button and disconnected the half press shutter feature. I have not had a back/front focus issue.

https://www.pentaxforums.com/forums/38-photographic-technique/236970-perfect-...everytime.html
09-03-2014, 10:23 AM   #7
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QuoteOriginally posted by Tjompen1968 Quote
I will try the Hold AF but that will counteract the speed of the AF when following moving targets...
Ah, Found it! This post and the entire thread may give you some ansers and ideas:

https://www.pentaxforums.com/forums/172-pentax-k-3/251413-post-your-k3-af-set...ml#post2695922
09-03-2014, 11:19 AM   #8
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So I have tested this and that during the evening and, as usual in these cases, there are some user related issues. I have fine tuned my technique and I think I have gotten rid of the problem I had before. I still have the C.18 set to OFF.

I guess I needed the support from the forum to get my act together.

/Thanks all!

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