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03-31-2012, 01:22 PM   #1
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Understanding Autofocus?

We have a K5 and the DA* 16-50 and it is so much more than our previous G11.

We seem to be challenged with the Autofocus.

There are many times when the red dot does not seem to appear in the viewfinder and the lens does not seem to adjust.

The owners manual is a bit complicated. The AF.C seems to be a better setting for most situations as it always adapting to what is happening.

Any tips appreciated.

03-31-2012, 01:48 PM   #2
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Several reasons the lens may not adjust:
-the camera may have gone to sleep, and you need to wake it up first
-there may be no adjustment needed
-in low contrast situations the camera may not be able to get a lock
You do not say but I assume you mean that when you take a shot and get no red light it is out of focus?

The owners manual is not complicated, if anything it is too simplistic. It is written to describe the functions of the camera, not how to use them. I think a lot of us would appreciate something that does a better job of explaining things but as a manual that's what you get. There used to be a series of books called Magic Lantern but as far as I know there is no plan to have one for the K-5. Which means you are stuck with this forum, so just ask!

The only time I use AF.C is for birds in flight, I think AF.S produces better results as you can never be sure exactly what AF.C is locking onto. I also only use single point focusing, I do not trust the camera to focus on the subject's eye for example if that is what I want. Far too easy for the camera to lock onto the nose or ear or whatever. Some of these errors are covered up when using the kit lens or any lens at smaller apertures, but the DA*16-50mm goes to f/2.8 and at that aperture your depth of focus can get too narrow.
03-31-2012, 01:51 PM   #3
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Just want to say one thing. The red dot is just telling you where it is focusing, not telling you things are in focus. The little green hexagon at the bottom inside the viewfinder tells you when things are in focus.
03-31-2012, 02:32 PM   #4
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AF.S is more accurate then AF.C and AF.S does a double focus check, Pentax is one of the few to actually do that these days.

03-31-2012, 02:40 PM   #5
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Good info above. To summarize:

Red dot means, "This is a focus point".
Green hex means, "Focus confirmation".
Green hand means, "Shake reduction is stable".
AF.S means "Autofocus for confirmation, and shoot".
AF.C means "Shoot without waiting for confirmation".

So if you want sharp images, do this:

1) Set SR on (for shutter speeds slower than 1/5FL).
2) Set AF to AF.S.
3) Half-press the shutter.
4) If you have SR on, wait for green hand (SR engaged).
5) Press the shutter. When green hex (focus confirmation) appears, the shutter fires.

Last edited by Bramela; 03-31-2012 at 02:47 PM.

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