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09-24-2010, 08:24 AM   #1
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KX and Focus Issues

Hi. I need to know if a new Pentax KX, or the lenses, are defective.

I bought my father a KX kit with the 18-55 and 55-300 lenses.

He shot about 100 test pics in RAW + JPEG, auto and manual focus, and about 80% of them were out of focus.

I then tested the camera,in RAW + JPEG, with both lenses. Ex. short, med. long shots with the both lenses (manual and auto focus), and some close (macro) shots with the 18-55.

Of my 318 pics., about 295 were out of focus, eg. the focus point of the subject was blurred. There is a point of focus, but I can not tell if it is always before or behind the point of focus.

I was test shooting in bright sunlight, so camera shake should not be an issue.



Thanks

P.S.

Both my father and myself wear glasses. This has not proven to be an issue with other DSLRs.


Last edited by dmfw; 09-24-2010 at 08:34 AM. Reason: Adding
09-24-2010, 08:38 AM   #2
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Seems unlikely it would be the lenses if pictures from both are bad. Can you post some examples? Does the in focus indicator light up and beep?

Which AF point mode are you using? I find that for me the single center point provides the most consistent focusing. YMMV of course.

Are you holding the shutter button half way until both the in focus and the shake reduction indicators light?

Have you tried taking a picture with live view zoomed in? You might need a tripod to really do a good test.
09-24-2010, 09:06 AM   #3
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You need to read the Focusing section in the Operating Manual .
I think you don't have sharp pictures because of the camera still in Auto (11 AF Points) which is default .
You set the camera to AF-S, Central Focus Point then enjoy it .
09-24-2010, 10:07 AM   #4
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The reasons for OOF pictures in AF mode would be totally different the reasons for OOF pictures in MF mode. So you'd want to post both kinds of pictures, with information about exactly where you tried to focus and how you tried to make the camera focus where you wanted. Then maybe someone could offer useful advice.


Last edited by Marc Sabatella; 09-25-2010 at 04:56 PM.
09-24-2010, 02:01 PM   #5
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Here are 5 example pics. that I shot.

These with the 70-300mm/Manual

KXTest-0001.jpg - 1.2 Mb
KXTest-0002.jpg - 1.2 Mb

These with the 30-70 in Manual.
KXTest-0003.jpg - 889.4 Kb
KXTest-0004.jpg - 797.4 Kb
KXTest-0005.jpg - 963.3 Kb

All APPEARED to be in focus in the viewfinder.

Note These were RAW files converted to JPG for faster downloading.

Also, all were short with a speed of 1/250 or faster, F5.6 for KXTest-0005.jpg and f7.1 for the others.

(Do I need F11+ for any DOF on this camera?)

Also, today I tryed the different auto focus modes, ex. center. They did not appear to address the issue.
09-24-2010, 02:08 PM   #6
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QuoteOriginally posted by Marc Sabatella Quote
The reasons for OOF pictures in AF mode would be totally different the reasons for OOF pictures in MF mode. So you'd want to post both kinds of pictures, with information abot exactly where yu tried to focus and how you tried to make the camera focus where you wanted. Then maybe someone could offer useful advice.
I tried the AF feature with both 11, 5 and center focus options. With center, I centered on the object and shot, but the focus was incorrect.

On manual. you have to try and focus using the viewfinder. The KX does not have any focus ring, so I think that it may be a best guess. I plan to let a photo friend, who does not wear glasses, test the camera and see if that may be the issue.
09-25-2010, 05:00 PM   #7
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You don't say exactly what *part* of the pictures appeared to be in focus in the viewfinder. not sure what you mean about the Kx not having a focus ring - focus rings are never on camera, they are on lenses, and I'm sure both the lenses you mentioned would have focus rings.

In any case, looking at the first picture, part of it *is* in perfect focus. Most isn't, because the depth of field is not enough to encompass that whole area. Are you familiar with depth of field? Also, the picture appears blurry from camera shake, suggesting shutter speed was probably not fast enough for the focal length.
07-29-2011, 02:26 AM   #8
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My name is Javier, event photographer and owner of a Pentax K-x. I was having similiar issues from dmfw. So if I set my camera to AFS central focus, the end result will be sharp images of the center focus of the subject and it will resolve this issue that I am having. Reason why I ask my last event shoot, which was a wine event, I had some pictures taken of guests of the event that were somewhat barely out of focus, on automatic using a 18-55 mm camera, thinking it was the shake reduction sensor having an issue. Been a Pentax user for the last 20 years and this was my concern.

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