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09-09-2012, 04:37 AM   #16
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I almost always use the center point focus setting. I can hardly think of a time that I wouldn't. As jatrax said, I don't know how the camera is supposed to know what
I want in focus when it's set to 11 zone. I'd rather choose.

09-09-2012, 05:03 AM   #17
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When I have the dial set to "sel"....I am selecting the point. That's my point of the post. I'm selecting the point and the camera never gets it right. If Im shooting in a burst mode for candids with a senior, and I want a particular composition, I'd never be able to use AF center. I want to keep my camera in the same spot for multiple exposures. You can't do that with AF center, even for something as simple as the rule of thirds.
09-09-2012, 06:09 AM   #18
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Have you tried to focus the shot in live view using constast detection, this might tell you if the Auto AF is up the put.
09-09-2012, 06:42 AM   #19
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You say you used the centre point, yet your son's eye is not in the centre. Have you cropped the picture. or did you recompose. If you recomposed did you let you finger slip off the button?

Secondly, measure out a suitable distance, and see if the camera focuses with this number on the lens.

09-09-2012, 07:13 AM   #20
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QuoteOriginally posted by arnold Quote
You say you used the centre point...
What he actually said: "I had the camera set to AF select and had the dot right on my sons eye."
09-09-2012, 07:16 AM   #21
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This is, in my opinion, the best technique for determining if you need to make a micro adjustment:

AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X
09-09-2012, 07:27 AM   #22
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QuoteOriginally posted by Jeff Charles Quote
What he actually said: "I had the camera set to AF select and had the dot right on my sons eye."
Yes OK. I assumed wrongly he selected the centre point, and put the centre point on his son's eye, which should put the eye in the centre of the picture. Obviously the point he did select didn't work.

Last edited by arnold; 09-09-2012 at 07:32 AM. Reason: Correction
09-09-2012, 08:16 AM   #23
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OP are you sure that every time you go an select a specific AF point, you aren't just pressing the OK button after you have selected an AF point, and thereby reseting the AF to the centre-point every time? Or have you set the camera to remember the last AF point you manually selected, so the wrong point is stored in memory and used for the next shot? It could be a simple but regular slip of the thumb like that causing your issues.

Weirder things have happened - eg some people have had baffling camera problems caused by wearing baseball caps that do stuff like regularly press buttons or block the pop-up flash.

Anyway I just did a series of simple AF tests where I had a rectangular folded constrasty printed map in the foreground. Behind it about 60cm was a book case full of books and junk. I put the camera in AF-S, turned on the AF assist light, then would select for example the top left AF point, and then achieve focus on the top left corner of the map, then move the AF point to the books in a small series of steps while pressing the AF, and observing at what point the focus moved to the books in the background from the map in the foreground. And then from the books to the map. I then did the same with the far top right AF point. Etc.

If you do this you will see how much space there is around each AF point as you work from foreground to background objects. There was a distinct zone around each AF point where it was able to work. It wasn't a 'pinprick' but a region.

Then with one AF point set on for example a book in the background, I would step back a bit and then re-try AF. Usually the camera held AF on the selected plane no problem.

Even doing this close-up with something with *razor thin* DOF like a 300mm lens wide-open there were no surprises. The AF points worked predictably and pretty OK. The biggest AF imprecision came when using the two non cross-type AF point points on the far right and far left. They were sometime very slow to find contrast and thus something to lock onto.

09-09-2012, 08:21 AM   #24
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QuoteOriginally posted by Deiberson Quote
I've been dealing with focus issues since I've been with Pentax. K-10, K-x and now the K5...

Is there a "lens adjustment" setting that compensates for this? If so please explain what it does and how it works in detail. I am unfamiliar.
Is your K-5 is consistently front focusing? If so, it sounds like a calibration problem.

The K-5's AF adjustment is on page 4 of the Custom Setting Menu, item number 26, AF Fine Adjustment.

I like the moire pattern AF adjustment method, which is explained here, but just taking a series of shots of a flat object while varying the AF adjustment works OK too. (Between each test shot, defocus the lens.)

That you've had trouble with other Pentax cameras is strange. I had a K-10D, and it did not misfocus. Also, my K-5 focuses accurately, although with occasional misses.

A couple of other observations: Your sample shot was taken in good light according to the EXIF, so a low-light AF problem is not the issue. Also, if the K-5's relatively large AF frame was the cause, the bowl edge near the baby's eye, or the background just behind the baby would have been in focus.

Jeff
09-09-2012, 08:28 AM   #25
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QuoteOriginally posted by MPrince Quote
This is, in my opinion, the best technique for determining if you need to make a micro adjustment:

AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X
Unfortunately, the northlight-images link is not working now. A Google search on "AF adjust moire" finds other sites that explain the technique.
09-10-2012, 01:09 AM   #26
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QuoteOriginally posted by Deiberson Quote
I've been dealing with focus issues since I've been with Pentax. K-10, K-x and now the K5.....
Kevin
I really do want to be rude here, but it occurs to me that if the op has had focus problems with every Pentax body he has owned the problem cannot be the K5 body.
so whats left?

1 every lens is faulty
or
2 there is a technique problem [read operator error]

from the op posts he would appear to be using the focus system correctly so the only suggestion I have is to [using the same body and lens that was used on the baby] set the camera is set up on a tripod and try the old simple line of batteries test and see what is going on. try it with a diagonal line and with a straight line .

Photo Tips and Sips: The Poor Man's (or Woman's) Focus test
hope that helps
09-10-2012, 01:58 AM   #27
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I've read this in a post here on the forums, and I agree completely, fixed my focus issues once I knew - can't find the original post now, which explained the situation much better than I can, so if anyone has a link, do post it.

But here is the jist of it: on Pentax DSLRs, the focus "point" the red squares are not the actual focus point. The actual focus "point" is a much larger cross "+" around this red square (for cross type points). So, if you place the red square on the eye, the AF will pick something (probably the best contrast, closest point) anywhere along the axes of this cross, maybe the nose, maybe the blanket, and so on. When I tested this theory when I first heard it, I could confirm that's what happens, and that cross is much bigger than you would imagine.

Again, the best source would be the original post I read here - hopefully someone will know how to find it.
09-10-2012, 07:26 AM   #28
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Yes I can't find it either but essentailly the centre point is not the little red square but the are bounded by the [ ] lines in your view finder.
if a face does not entriely fill that area then anything with a high contrast behind or in front might will be picked up instead of the face.

Last edited by adwb; 09-11-2012 at 12:43 AM.
09-10-2012, 02:52 PM   #29
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QuoteOriginally posted by atekant Quote

But here is the jist of it: on Pentax DSLRs, the focus "point" the red squares are not the actual focus point. The actual focus "point" is a much larger cross "+" around this red square (for cross type points). So, if you place the red square on the eye, the AF will pick something (probably the best contrast, closest point) anywhere along the axes of this cross, maybe the nose, maybe the blanket, and so on. When I tested this theory when I first heard it, I could confirm that's what happens, and that cross is much bigger than you would imagine.
.
I don't see any crosses, just red points on my K5. The red dot flashes when it locks to something close to where it is sitting.
09-10-2012, 04:37 PM   #30
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QuoteOriginally posted by arnold Quote
I don't see any crosses, just red points on my K5.
The 'cross' merely refers to how the AF sensor point works, not what you see in the AF overlay on the viewfinder.

QuoteOriginally posted by arnold Quote
The red dot flashes when it locks to something close to where it is sitting.
Exactly. The red dot is just an indicator of which fixed AF sensor has found something contrasty to grab onto within a region of the scene.
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