Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-21-2012, 05:09 PM   #1
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Yet Another AF Failure From My K-5



I used Auto-AF (11 points) and AF-S in this image. The lens was Sigma 30mm f/1.4.

I think the K-5 thought the red-shirt man in the left-back was more interesting than the man just in front of itself. (Face blurred over request).

So what do you think?

07-21-2012, 05:11 PM   #2
Veteran Member
creampuff's Avatar

Join Date: May 2007
Location: Singapore
Photos: Gallery
Posts: 3,955
User error imo. Focus and re-compose? Manual focus?
07-21-2012, 05:14 PM   #3
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Original Poster
No re-compose. I don't focus and re-compose, I choose a relevant focusing point if necessary. And as I said, I used Auto-AF (11 points) and AF-S in this image. That means I used AF.
07-21-2012, 05:15 PM   #4
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,758
QuoteOriginally posted by Crosshair Quote
No re-compose. I don't focus and re-compose, I choose a relevant focusing point if necessary. And as I said, I used Auto-AF (11 points) and AF-S in this image. That means I used AF.
He was giving suggestions as to how to avoid those problems in the future. It's obvious the AF system locked on to the point of highest contrast, the guy with the red shirt.

07-21-2012, 05:18 PM   #5
Pentaxian
JinDesu's Avatar

Join Date: Jun 2011
Location: New York City
Photos: Gallery
Posts: 5,625
Center point helps a lot. Focus and recompose too.
07-21-2012, 05:18 PM   #6
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Original Poster
Oh if so, I must apologize @creampuff. Sorry I took it the wrong way
07-21-2012, 05:20 PM   #7
Veteran Member
creampuff's Avatar

Join Date: May 2007
Location: Singapore
Photos: Gallery
Posts: 3,955
Mental note: K-5 with Sigma 30mm combo has difficulty focusing on hairy chested guys...
Joking of course.
07-21-2012, 05:24 PM   #8
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Original Poster
so I thought that the Auto-AF option would focus on the nearest object of contrast. or it was the same in nikon anyway. I produced that way with the nikon d90 in the time.

the k-5 chooses the point of highest contrast in the frame, disregarding its position. is that so?

07-21-2012, 05:26 PM   #9
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Original Poster
@creampuff well I must say I thought those hairs made up a contrast against the cream color but as you pointed out the k-5 disregarded it.
07-21-2012, 05:31 PM   #10
Veteran Member
roentarre's Avatar

Join Date: Oct 2006
Location: Melbourne, Australia
Posts: 11,794
Such is life with AF
07-21-2012, 05:43 PM   #11
Pentaxian
calsan's Avatar

Join Date: Nov 2008
Location: Perth, Australia
Photos: Gallery
Posts: 1,386
Do you have the red dots turned on? Because then you would at least see the focus point the camera is using.
07-21-2012, 05:46 PM   #12
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Original Poster
Yeah, I had them turned on and as fas as I can remember, two points in the center (over the face and upper chest) were used. If side ones were used I'd notice right away and re-take the shot. So bad I didn't stoop to zoom-in and check the focus. Seemed OK in the instant preview so I moved on.
07-21-2012, 05:50 PM   #13
Pentaxian
wizofoz's Avatar

Join Date: Apr 2009
Location: Melbourne, Outer east.
Photos: Gallery | Albums
Posts: 1,655
If I'm not mistaken, the center AF sensor is a lot bigger then the red dot or the central circle of the standard focussing screen might suggest. It is entirely possilbe that the right shoulder/upper arm of the guy in the red shirt and the face and helmet of the intended target were both within the crosshairs (pun intended) of the AF sensor. If that is the case the sensor would select the area of highest contrast as the focus point, It is a contrast detect Auto focus method after all.

It may be that the error is one of misunderstanding how the AF function works.

Last edited by wizofoz; 07-21-2012 at 05:51 PM. Reason: clarity
07-21-2012, 05:54 PM   #14
Veteran Member
Crosshair's Avatar

Join Date: Apr 2012
Location: Istanbul
Posts: 332
Original Poster
@wizofoz yeah, your suggestion makes sense. the central focusing area extending and overlapping the red guy in the back. so it is proof that the k-5 disregards distance in focusing and looks for the highest contrast on Auto-AF or Single-AF around which point is selected.
07-21-2012, 05:59 PM   #15
Veteran Member
Philoslothical's Avatar

Join Date: May 2011
Posts: 1,723
All of the focus points are much larger than indicated. Auto-11 is a crap shoot at best. Imo, it's basically telling the camera "read my mind" about what to focus on. It is a much more reliable technique to either dial in an AF point to use, or use the center one and recompose as needed.
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!
af failure, camera, dslr, k-5, k-5 ii, k-5 iis, k5, pentax k-5
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
kr major failure digi_photog Pentax K-r 2 11-13-2011 10:17 PM
DA* 50-135mm failure sean Pentax SLR Lens Discussion 47 05-19-2011 08:47 PM
Is k-5 a failure? yusuf Pentax K-5 272 03-30-2011 10:20 AM
Failure to Fire Chaos_Realm Troubleshooting and Beginner Help 10 03-08-2011 06:37 PM
Failure to Launch hriddle Troubleshooting and Beginner Help 7 01-09-2011 03:52 PM



All times are GMT -7. The time now is 03:30 PM. | 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