Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-09-2012, 06:50 AM   #1
Inactive Account




Join Date: May 2010
Posts: 37
K-x issues with autofocus

Hi there,

I'm having a problem with autofocus on my k-x camera with Tamron 17-50mm F2.8 lenses. Basically the problem is - in about 50% of the times I'm trying to take a picture the autofocus does not work, I mean it simply refuses to focus. Usually moving a camera a little bit helps, but sometimes no matter what I do it simply would not autofocus!

What's wrong?

09-09-2012, 07:28 AM   #2
Loyal Site Supporter
THoog's Avatar

Join Date: Aug 2012
Location: North Carolina
Photos: Gallery | Albums
Posts: 3,486
That lens can be a little soft wide open. It sounds like your copy is just soft enough to give the AF system problems. My K-r also has problems focusing with the Tamron 17-50 f2.8 (but my K-x did not, or had less noticeable problems, and my K100D never had problems with it). It seemed to do much better when I switched to AF.S (single-shot) mode. AF.A and AF.C almost always missed focus. You could also try setting the AF to center-point focusing to see if that helps.
09-09-2012, 07:37 AM   #3
Veteran Member
crewl1's Avatar

Join Date: Jul 2010
Location: Los Angeles, CA
Photos: Gallery | Albums
Posts: 9,797
Try cleaning the contacts on both camera and lens mounts to see if it helps.
09-11-2012, 08:27 AM   #4
Inactive Account




Join Date: May 2010
Posts: 37
Original Poster
I've also noticed that sometimes the camera would switch from AF to MF and vice versa even though it is set to AF! How can it be!?

09-12-2012, 12:42 AM   #5
Inactive Account




Join Date: May 2010
Posts: 37
Original Poster
BTW, non of the above suggestions helped much. Any other ideas? I don't even know if this is a problem that can be repaired or not, or if this a camera or lenses problem...
09-12-2012, 07:51 AM   #6
Veteran Member
crewl1's Avatar

Join Date: Jul 2010
Location: Los Angeles, CA
Photos: Gallery | Albums
Posts: 9,797
QuoteOriginally posted by moshepupkin Quote
or if this a camera or lenses problem.
If other lenses work fine then it is a lens problem. If all lenses act the same way then it is a camera problem. Have you tried other lenses?
09-12-2012, 08:38 AM   #7
Veteran Member




Join Date: Dec 2010
Location: Manila
Photos: Gallery | Albums
Posts: 2,190
QuoteOriginally posted by moshepupkin Quote
Hi there, I'm having a problem with autofocus on my k-x camera with Tamron 17-50mm F2.8 lenses. Basically the problem is - in about 50% of the times I'm trying to take a picture the autofocus does not work, I mean it simply refuses to focus. Usually moving a camera a little bit helps, but sometimes no matter what I do it simply would not autofocus! What's wrong?
QuoteOriginally posted by moshepupkin Quote
I've also noticed that sometimes the camera would switch from AF to MF and vice versa even though it is set to AF! How can it be!?
When did you buy your camera? Mine was circa 2010, and I'm encountering similar problems. I figured out a solution though I am not sure if it is the same for your problem. There are a few things you need to make sure first:

1. The problem is that the focus gets stuck at either MF or AF, regardless of, for example, the switch was set to AF and the display says "MF" or when the switch is at "MF" but the display (and active focus mechanism) is still AF.

2. Clean all contacts on the camera mount. DO NOT use any liquid cleaning agent, a clean microfiber cloth will do.

3. That the problem exists on all lenses you mount on your K-x.
...Check the screwdrive screw with the lens off- it should be perfectly centered in the hole it comes in and out of. A little difference won't matter, but if it, say, skids along the edges when it pops out of the body (in AF mode), have a Pentax technician check it.

4. Check the switch - remove the lens first. When you switch the focus switch to AF, the screwdrive screw should pop out of the body. In MF, it should sink into the body. Also, while in AF mode, the screw should be able to sink into the body given some pressure - this ensures that the spring underneath it is not damaged.

5. If all things are how they should be as in #4, carefully move the switch between the modes. You should feel something like a slight semi-click before it moves fully down or up. This means that somehow, one of the contacts that confirm that the camera has switched AF modes has loosened up or is not aligning properly. This solution will work but you have to be very careful in switching from now on, if you want to avoid spending on body repair.


IF the AF works properly on other lenses, then it's one or other particular lenses your K-x is having problems communicating with. If #5 does not solve the problem, have an authorized (or otherwise very knowledgeable) camera technician check it.

The screwdrive AF problem also should not affect your camera's ability to use the AF of KAF3/SDM lenses

Last edited by Alizarine; 09-12-2012 at 09:59 AM.
09-12-2012, 08:44 AM   #8
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,684
QuoteOriginally posted by moshepupkin Quote
I'm having a problem with autofocus on my k-x camera with Tamron 17-50mm F2.8 lenses. Basically the problem is - in about 50% of the times I'm trying to take a picture the autofocus does not work, I mean it simply refuses to focus.
I don't understand the problem from your description. Do you mean it doesn't try to focus at all, or that it tries, but can't achieve focus lock (i.e. hunts)? If the former, it sounds like the camera or camera/lens interface, if the latter I would suspect the lens.

QuoteOriginally posted by crewl1 Quote
If other lenses work fine then it is a lens problem. If all lenses act the same way then it is a camera issue. Have you tried other lenses?
Diagnosing whether it's the camera or lens is definitely the best place to start.

09-13-2012, 02:02 PM   #9
Inactive Account




Join Date: May 2010
Posts: 37
Original Poster
QuoteOriginally posted by audiobomber Quote
I don't understand the problem from your description. Do you mean it doesn't try to focus at all, or that it tries, but can't achieve focus lock (i.e. hunts)?
In the cases when the camera cannot achieve a focus lock, I've noticed that it keeps switching spontaneously from AF to MF, according to what is displayed on the screen.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
autofocus, camera, k-x, pentax help
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tamron SP AF10-24 mm F3.5-4.5 Autofocus Issues DWPhoto Pentax SLR Lens Discussion 2 06-22-2012 10:17 AM
Autofocus issues 50mm with new K5 ptax Troubleshooting and Beginner Help 13 12-05-2011 09:56 PM
For Sale - Sold: [Worldwide] Cheap K20D (w/ autofocus issues) dgaies Sold Items 6 03-05-2010 06:20 PM
Issues with K10D Autofocus lamgray Pentax DSLR Discussion 3 10-26-2008 09:38 PM
Autofocus issues wide angle on K10d timmciglobal Pentax DSLR Discussion 6 07-25-2007 11:50 AM



All times are GMT -7. The time now is 07:15 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top