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09-28-2014, 03:34 AM   #1
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Multi point focusing why?

As a long time user of single centre point focus ,I never feel the need to keep the body still and try to move the focus point about , and I'm fine with focus recompose, it has stood me in good stead for years at weddings and other highly fluid events,but having recently got rid of my K5 bodies for K5IIs bodies there is now a very decernable accuracy to the centre point that was not there before.

I note the K3 seems to not only have these same (smaller?) cross point focusing points but a lot of them available as multi point

Can somebody please explain where or when using multi point (using 5 or 9 ) or whatever would be beneficial to focusing compared to a single point?

I have tried out with the new bodies and occasionally a second red spot appears apart from the centre one, so what is the focus detection system trying to focus on? The centre one , the other one ,somewhere in between or what?

09-28-2014, 03:44 AM   #2
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The only use I find for multi point focusing is for tracking moving subjects.

AFAIK, when two different red dots are lit both points are in focus and they are both on the same focal plane (I think that is the correct term).
09-28-2014, 04:06 AM   #3
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I think I remember Adam explained in another thread the multiple red points appearing is a reflection off the red point due to it's brightness.
09-28-2014, 04:21 AM   #4
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Multipoint focusing is for when you are shooting action and need the camera to focus on possibly off center subjects that are moving in your frame. The camera will attempt to guess what target you want based on subject distance and general motion/calculations. It will light up the off center focus points that are currently being used for focus.

I just tested on my k-3 and I can't get multiple points to pop up, so I assume Oldbayrunner is correct regarding that item. I know that some other brands will light up multiple focus points at the same time when showing what segments are tracking. On my k-3, it lights up the individual focus points as it tracks.

09-28-2014, 04:21 AM   #5
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I can imagine two other reasons for multiple focus points. One is if you have a very thin DoF so that recomposing might shift focus too much. The other is if you want to use AF with a tripod (but then I suppose live view would make more sense...).
09-28-2014, 07:27 AM   #6
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QuoteOriginally posted by JinDesu Quote
The camera will attempt to guess what target you want
I just can't work with that--I'll miss the focus on my own thank you ;~)
09-28-2014, 09:13 AM   #7
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QuoteOriginally posted by Pablom Quote
AFAIK, when two different red dots are lit both points are in focus and they are both on the same focal plane (I think that is the correct term).
That is my understanding as well. It happens very rarely, though and the display is not quite as entertaining as a Nikon.


Steve
09-28-2014, 12:00 PM - 1 Like   #8
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Well, try 3-D tracking with a single point, moving object and shoot max FPS the camera can do. You should nail more in-focus shots in general with the array of points. And there is further consideration and variation on group focusing points. In the group of points do you want to favor the closest thing, farthest or average what it sees as the plane of focus. Ideally a camera will give you the options to favor the near, average or background that's in your array of focus points.

09-28-2014, 12:58 PM   #9
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QuoteOriginally posted by tuco Quote
Well, try 3-D tracking with a single point, moving object and shoot max FPS the camera can do. You should nail more in-focus shots in general with the array of points. And there is further consideration and variation on group focusing points. In the group of points do you want to favor the closest thing, farthest or average what it sees as the plane of focus. Ideally a camera will give you the options to favor the near, average or background that's in your array of focus points.
This is articulated really well. As a Canon shooter I make very similar AF configuration decisions all the time. The ability to use multiple AF points in a variety of contexts took me a while to learn to use well, as I was coming from a basic center AF model. Now, for example, I find myself cycling through multiple pinpoint AF points in closeup shooting situations with tripod, and am finding it as effective and more convenient than LiveView manual focusing.

Having owned both the K-3 and the 5DMK3, I find that a key difference between AF systems (and I'm lumping Nikon systems in with Canon) is that the approach and tools for managing these complexities on the Pentax side is not presented to the user as effectively. The actual technical capabilities of the K-3 may be very close to Canon and Nikon levels, but as a user you are left with more ambiguity. And thus the perception of the AF system "guessing" for tracking action leads to a lack of confidence in the system's abilities. I think my 5DMK3 is better than I am for accurately tracking action when I configure it correctly.

M
09-28-2014, 06:37 PM   #10
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QuoteOriginally posted by Oldbayrunner Quote
I think I remember Adam explained in another thread the multiple red points appearing is a reflection off the red point due to it's brightness.
I get that if I am shooting with my glasses on.


Steve
09-28-2014, 11:34 PM   #11
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Thank you every one for the answers
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