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06-23-2016, 11:11 AM   #1
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AF points

I've always used centre AF and recompose, being fully aware of the potential geometrical errors, particularly when DOF is shallow.

I've also been assuming that people who use AF point selection do so when there are no timing constraints i.e. when conditions are such that one can take the time to select the appropriate AF point before shooting. Such is not always the case, obviously. Therefore, I was surprised to see a post in another thread by Benjikan, where he makes a reference to AF points while shooting models https://www.pentaxforums.com/forums/190-pentax-k-1/323950-tony-northrup-k-1-r...ml#post3688256

I've tried using Auto AF point selection, but this seems to select a point almost at random Using SEL works, I guess, but is too slow at times. So the question is: how do people, other than those using centre AF/recompose, typically use their AF, especially when trying to not take too long for each shot?


Last edited by bxf; 06-23-2016 at 12:26 PM.
06-23-2016, 11:23 AM   #2
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My father uses auto focus point selection when he does pin up model shoots. I also use it when shooting weddings and events. It is just like getting used to back button focus. Once you get used to using it there is very little time difference between using it and using focus and recompose. You just have to force yourself to use it until you get used to it. That is how I started using back button and focus point selection.
06-23-2016, 11:30 AM   #3
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Well, the problem you expose is a problem since the AF points exists.
I'm well aware of your question, as i asked it myself too
Especially when a subject is moving while you're center AF-ing it.

in this case, 2 solutions if you can move your body/legs/fingers :
you move along with the subject while appreciating the distance/movement.
you have AF lenses you can manual focus on pentax, while appreciating distance/movement (and finally maybe this is not an AF solution...haha)

This is what i prefer.

But , if i'm too lazy, i can also center AF and AF-C , to track my subject. Depending on the subject , in can work or not work.

In any case, you need to anticipate a bit. That's all.

I don't have any other clues !
06-23-2016, 11:58 AM   #4
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QuoteOriginally posted by macman24054 Quote
My father uses auto focus point selection when he does pin up model shoots. I also use it when shooting weddings and events. It is just like getting used to back button focus. Once you get used to using it there is very little time difference between using it and using focus and recompose. You just have to force yourself to use it until you get used to it. That is how I started using back button and focus point selection.
I've experimented with AUTO a couple of times, but it seems to have a mind of its own, which unfortunately differs from mine substantially I don't know how it decides which AF point to use, but it seems to be the wrong one more often than not.

06-23-2016, 12:03 PM   #5
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QuoteOriginally posted by bxf Quote
I've always used centre AF and recompose, being fully aware of the potential geometrical errors, particularly when DOF is shallow.

I've also been assuming that people who use AF point selection do so when there are no timing constraints i.e. when conditions are such that one can take the time to select the appropriate AF point before shooting. Such is not always the case, obviously. Therefore, I was surprised to see a post in another thread by Benjikan, where he makes a reference to AF points while shooting models.

I've tried using Auto AF point selection, but this seems to select a point almost at random Using SEL works, I guess, but is too slow at times. So the question is: how do people, other than those using centre AF/recompose, typically use their AF, especially when trying to not take too long for each shot?
Here is my flow, it may not be the greatest but it works for me and I'm still learning!

Center AF - single point 80% of the time.
Spot Metering
AF-S
Back-buttoned AF

Most of my shots have to be quick and I don't have time to mess with selecting my single AF point.
I find that Center AF - Single with Spot meter and back button AF works the best and fastest for my wildlife shots.

If I have time to frame my shot shoot a few tests and recompose, than AF - single point SEL still with Spot meter.

Here's a perfect example of when the single AF worked wonders for me... AF-C and AF-A, Auto AF and Zone Sel; none of these could nail the focus on the subject in and out of filtered light with branches, leaves and flowers all around it. I could only get the shot with a single spot AF and spot metered.

06-23-2016, 12:04 PM   #6
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QuoteOriginally posted by phat_bog Quote
...if you can move your body/legs/fingers...
Nope. All of these components are in fixed positions

Other than that, my question wasn't really focusing() on moving subjects. Rather, on off-centre ones, where centre-focus/recompose may render the subject out of perfect focus.

---------- Post added 23-06-16 at 20:11 ----------

QuoteOriginally posted by UserAccessDenied Quote
...I could only get the shot with a single spot AF and spot metered.
But in such situations, your subject is presumably centred anyway, no? So centre point is the obvious choice anyway.

(BTW, using spot metering should be irrelevant with respect to focusing.)
06-23-2016, 12:23 PM   #7
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QuoteOriginally posted by bxf Quote
Nope. All of these components are in fixed positions

Other than that, my question wasn't really focusing() on moving subjects. Rather, on off-centre ones, where centre-focus/recompose may render the subject out of perfect focus.

---------- Post added 23-06-16 at 20:11 ----------


But in such situations, your subject is presumably centred anyway, no? So centre point is the obvious choice anyway.

(BTW, using spot metering should be irrelevant with respect to focusing.)
Right, just figured I throw in the metering settings anyways...
I shoot manual so the metering mode doesn't really matter too much, I have heard that the "Focus and Recompose" style of shooting can had different affects depending on the metering mode you have selected... Could be wrong?

And you're exactly correct, when the subject is perfectly centered then it's a wash. But often times my subject is so fast I'd rather nail focus and get the shot slightly off centered than try to switch my AF point and lose the shot altogether.

Just personal experience, when I was learning which settings I preferred I lost a lot of shots from fumbling with my camera when a photo opportunity presented itself.
Now I just leave AF center spot by default. Get that first shot, even if the focus does drop off a bit (recompose/DOF) then I'll go back and try to select an AF point and get the perfect shot. I like to know I'm not going to walk away empty handed when I see something now.
06-23-2016, 01:05 PM   #8
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QuoteOriginally posted by bxf Quote
I've tried using Auto AF point selection, but this seems to select a point almost at random Using SEL works, I guess, but is too slow at times. So the question is: how do people, other than those using centre AF/recompose, typically use their AF, especially when trying to not take too long for each shot?
With the K-1 you no longer need to press the AF point selection button to get the rear controller to change AF points, so moving the active point(s) around is quick. There is a custom function that makes the AF point selection button grant access to the four sub-menus instead, so that the four-way controller defaults to moving AF points around. This is how things have always worked on Canon and Nikon bodies, so perhaps Tony is used to that.

Similarly, on the K-3 as long as you don't swap out of AF point selection mode, things should be quick, but it can be tricky if you're shooting under pressure.


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06-23-2016, 01:25 PM   #9
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QuoteOriginally posted by Adam Quote
With the K-1 you no longer need to press the AF point selection button to get the rear controller to change AF points, so moving the active point(s) around is quick. There is a custom function that makes the AF point selection button grant access to the four sub-menus instead, so that the four-way controller defaults to moving AF points around. This is how things have always worked on Canon and Nikon bodies, so perhaps Tony is used to that.

Similarly, on the K-3 as long as you don't swap out of AF point selection mode, things should be quick, but it can be tricky if you're shooting under pressure.
I suppose being used to some operations makes a big difference in "usability".

I was actually thinking about Benjikan's post, because we always see a model moving about while the photographer is shooting. But perhaps there are situations in which a series of shots are taken with the camera and model being in relatively fixed positions, so that one wouldn't have to change the AF point from shot to shot.

Last edited by bxf; 06-24-2016 at 05:02 AM.
06-23-2016, 09:18 PM   #10
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QuoteOriginally posted by bxf Quote
I've experimented with AUTO a couple of times, but it seems to have a mind of its own, which unfortunately differs from mine substantially I don't know how it decides which AF point to use, but it seems to be the wrong one more often than not.
Sorry for the confusion. I meant that we select the auto focus points ourselves. Not the camera doing it. I have never allowed the camera to select the point simply because I have read so many negative things about it.
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06-24-2016, 05:02 AM   #11
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QuoteOriginally posted by macman24054 Quote
My father uses auto focus point selection
QuoteOriginally posted by macman24054 Quote
Sorry for the confusion
Oh, I see. You meant My father uses auto focus point selection not My father uses auto focus point selection
06-24-2016, 07:25 AM   #12
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QuoteOriginally posted by bxf Quote
I've always used centre AF and recompose, being fully aware of the potential geometrical errors, particularly when DOF is shallow.

I've also been assuming that people who use AF point selection do so when there are no timing constraints i.e. when conditions are such that one can take the time to select the appropriate AF point before shooting. Such is not always the case, obviously. Therefore, I was surprised to see a post in another thread by Benjikan, where he makes a reference to AF points while shooting models https://www.pentaxforums.com/forums/190-pentax-k-1/323950-tony-northrup-k-1-r...ml#post3688256

I've tried using Auto AF point selection, but this seems to select a point almost at random Using SEL works, I guess, but is too slow at times. So the question is: how do people, other than those using centre AF/recompose, typically use their AF, especially when trying to not take too long for each shot?
The following is what I do on the K-1. But where possible I did the same on the K-3-series, although this really needs more pixels in the sensor.

I wrote about this in my review of the K-1. Here are two relevant pages, with some photos to illustrate what I was saying:

Review: K-1 auto-focus in practice

Review: K-1 for action photography

I do a lot of action photography. I nearly always use just the center AF point. On occasion I have used the center 9 points, but I could just about manage "for ever" if the K-3-series and K-1 only had one AF point!

Used like this, the K-3-series and K-1 are fast and pretty accurate, at least with the latest lenses. I have to crop afterward. (In effect, I'm doing "focus and shoot then compose in post-processing"). But there are lots of pixels in the K-1 sensor, at least, so even after I've thrown a lot away, there are normally lots left, and they are good pixels.

Last edited by Barry Pearson; 06-24-2016 at 07:33 AM.
06-25-2016, 05:04 AM   #13
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QuoteOriginally posted by Barry Pearson Quote
wrote about this in my review of the K-1. Here are two relevant pages, with some photos to illustrate what I was saying: Review: K-1 auto-focus in practice
Some useful info here. Thanks.
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