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05-24-2016, 02:45 AM   #1
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Afa afc afs

I am learning the K3 system but do have a few questions on the AF modes. Can someone break down exactly what AFS is/does and why it would be advantageous., AFC , and tracking a subject BIF etc , and AFA when would the auto system be best & why. I hope my questions are clear I am just trying to use this amazing computer to it's best potential and how the designers of the AF system feel would work the best in a given situation as I am sure they have put many hours into building it. Also trying to figure out the difference of red/white when selecting single point, select etc. I am just trying to wrap my head around better understanding to make better photographs.
Thanks in advance, Bob


Last edited by marquis1955; 05-24-2016 at 04:02 AM. Reason: Forgot something
05-24-2016, 04:32 AM   #2
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QuoteOriginally posted by marquis1955 Quote
I am just trying to wrap my head around better understanding to make better photographs.

Hi Bob. I hope this helps out a bit.


Focusing Modes | Understanding Autofocus Modes
05-24-2016, 04:47 AM   #3
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QuoteOriginally posted by pjv Quote
Hi Bob. I hope this helps out a bit.


Focusing Modes | Understanding Autofocus Modes
Thanks for the feedback and links , I have read them and also the PF K3 review and info about AF modes. I guess I am looking for some kind of and edge or better understanding to get better than 50 to 67 percent keepers on moving subjects, BIF etc. Hoping I was missing something (usually the obvious) I will keep shooting the aforementioned in AF-C and single point,spot or 9 point select, improve my technique, practice, practice,practice. I already have great lenses not much in telephoto lenses f2,8 ! Thanks again for the feedback.
05-24-2016, 04:53 AM - 1 Like   #4
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QuoteOriginally posted by marquis1955 Quote
Thanks for the feedback and links , I have read them and also the PF K3 review and info about AF modes. I guess I am looking for some kind of and edge or better understanding to get better than 50 to 67 percent keepers on moving subjects, BIF etc. Hoping I was missing something (usually the obvious) I will keep shooting the aforementioned in AF-C and single point,spot or 9 point select, improve my technique, practice, practice,practice. I already have great lenses not much in telephoto lenses f2,8 ! Thanks again for the feedback.
I would practice with SEL-9 and SEL-27 modes. Those are the most promising for tracking, IMO. Single point mode can really backfire unless you are able to predict the motion of the subject well.


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05-24-2016, 05:44 AM   #5
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QuoteOriginally posted by Adam Quote
I would practice with SEL-9 and SEL-27 modes. Those are the most promising for tracking, IMO. Single point mode can really backfire unless you are able to predict the motion of the subject well.
Thanks Adam I will work with your suggestions and appreciate the valuable feedback.
05-24-2016, 07:22 AM - 1 Like   #6
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If you have a particular situation, such as BIF, that you use regularly, I suggest using one of the User modes U1-U3 to save your setup. For example, my U1 is configured for birds in flight with TAv, AF.C, centre-weighted metering, and 27-point AF.
05-24-2016, 08:03 AM - 1 Like   #7
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I use TAV mode, AF.C, F8, 1250 Exposure Timing, Spot (center point) AF, Spot (center point) metering, SR on, and +.3 EV when I shoot birds in flight with my K-3II and Sigma 150-500 DG OS. I have the lens OS (Optical Stabilization) set to off because the SR in the camera is being used. I also save those settings to one of the User modes to have it readily available.
05-24-2016, 08:27 AM   #8
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QuoteOriginally posted by C_Jones Quote
I use TAV mode, AF.C, F8, 1250 Exposure Timing, Spot (center point) AF, Spot (center point) metering, SR on, and +.3 EV when I shoot birds in flight with my K-3II and Sigma 150-500 DG OS. I have the lens OS (Optical Stabilization) set to off because the SR in the camera is being used. I also save those settings to one of the User modes to have it readily available.
I appreciate the feedback !

05-24-2016, 11:27 AM - 1 Like   #9
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Ok, it is simple:
- AFS: camera software wait for AF lock confirm signal to stop the AF process.
- AFC: camera software keep the AF process running as long as the shutter button of AF button is being pressed, without considering AF lock confirm (this is to make the AF regulation running faster without waiting for AF lock interrupt).
- AFA: camera software run AFS mode and wait some time for AF confirm, if AF confirm isn't received the AF confirm is skipped and AF run in AFC mode.

Difference between white points and red AF points:
- white point aren't used until AF closure is achieved with the red point (selected point to first achieve focus), once red point AF is achieved, white points are enabled to AF to relay the red point.

Automode versus AF select modes:
- In auto-mode (AFS or AFC), there is not predefined AF point priority, all AF points are active, the rule that prevail is to focus on the subject closest to the camera or most contrasty surface if depth of field wide open is thin (that means when there is too much difference between out of focus point and point in focus, the AF module can evaluate distances). If the AF module is able to evaluate distances, the AF ring rotates from infinity to closest focus distance, depending which side of the middle of focus range is the lens AF ring set because the AF process is initiated. Auto AF mode are unreliable due to variety of image patterns and lighting conditions. The best is to select a priority AF point (red point) and select the AF point coverage depending on how much of the frame the subject may move in.
05-24-2016, 02:51 PM   #10
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QuoteOriginally posted by biz-engineer Quote
Ok, it is simple:
- AFS: camera software wait for AF lock confirm signal to stop the AF process.
- AFC: camera software keep the AF process running as long as the shutter button of AF button is being pressed, without considering AF lock confirm (this is to make the AF regulation running faster without waiting for AF lock interrupt).
- AFA: camera software run AFS mode and wait some time for AF confirm, if AF confirm isn't received the AF confirm is skipped and AF run in AFC mode.

Difference between white points and red AF points:
- white point aren't used until AF closure is achieved with the red point (selected point to first achieve focus), once red point AF is achieved, white points are enabled to AF to relay the red point.

Automode versus AF select modes:
- In auto-mode (AFS or AFC), there is not predefined AF point priority, all AF points are active, the rule that prevail is to focus on the subject closest to the camera or most contrasty surface if depth of field wide open is thin (that means when there is too much difference between out of focus point and point in focus, the AF module can evaluate distances). If the AF module is able to evaluate distances, the AF ring rotates from infinity to closest focus distance, depending which side of the middle of focus range is the lens AF ring set because the AF process is initiated. Auto AF mode are unreliable due to variety of image patterns and lighting conditions. The best is to select a priority AF point (red point) and select the AF point coverage depending on how much of the frame the subject may move in.
Hey biz-engineer Appreciate the detailed information and your taking time to give another insight to the K3 AF system ! Thanks again
05-24-2016, 02:57 PM - 1 Like   #11
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I use TAv with AF.C and 9-point select for my bird shots. But that is for birds in trees and shrubs...I rarely have success with BiF because that is not my primary subject. I usually miss when a shot presents itself because I forget to change my settings...
05-24-2016, 04:34 PM   #12
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QuoteOriginally posted by marquis1955 Quote
I appreciate the feedback !

You're welcome.
05-24-2016, 05:55 PM - 1 Like   #13
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I haven't touched Nikon equipment in a very long time, but I recall long ago they were using terminology such as "Predictive AF". I've always taken that to mean that there was some intelligence that attempted to predict the location of the subject at some future instant (i.e. when the shutter is actually fired), based on its velocity (i.e. direction and speed) as seen "just before", whatever that means.

Do all AF-C algorithms work as described above, or is this a completely separate concept?
05-24-2016, 06:22 PM   #14
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QuoteOriginally posted by bxf Quote
I haven't touched Nikon equipment in a very long time, but I recall long ago they were using terminology such as "Predictive AF". I've always taken that to mean that there was some intelligence that attempted to predict the location of the subject at some future instant (i.e. when the shutter is actually fired), based on its velocity (i.e. direction and speed) as seen "just before", whatever that means.

Do all AF-C algorithms work as described above, or is this a completely separate concept?
Is that kinda-like horse shoe & hand grenades ?
05-25-2016, 02:06 AM   #15
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QuoteOriginally posted by Adam Quote
I would practice with SEL-9 and SEL-27 modes. Those are the most promising for tracking, IMO. Single point mode can really backfire unless you are able to predict the motion of the subject well.
SEL 9 and SEL 27. I didn't know that. Nice to learn new things in the forum.
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